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D.H. Brown Associates, Inc. http://www.dhbrown.comA sum mary of this report is available to all of our subscribers free of charge. Sponsors of our co llaborative program in Systems Software (SS) receive the full report as part of our co mprehensive services. Those interested in the pro gram s hould contact Ken Mewes, Vice President Marketing at km ewes@dhbrown .com o r 914-937- 4302, ext. 272.

2001 UNIX Function Review

EXECUTIVE SUMMARY

5.50 6.00 6.50 7.00 7.50 8.00 8.50 9.00

UnixWare 7.1.1

AIX 4.3.3

Tru64 UNIX 5.1

HP-UX 11i

Solaris 8

Poor OK Good Very Good

Average of the funct i onal r at i ngs f or Scalab i l i t y, RAS, Sys tem Management ,In te rne t and Web-Appl ica t ion Suppor t , and Direc tory and Secur i ty Serv ices .

FIGURE 1: Overall Functional Ratings as of January 1, 2001In the leap-frogging game that is continuously played in the brutally competitivecommercial-server arena, Solaris 8 surges ahead to capture the overall lead forUNIX operating-system functions. Now that Sun has finally completed shippingall promised components in its operating environment, Solaris 8 occupies the topspot in RAS (Reliability, Scalability, and Serviceability) and Directory and SecurityServices, and also achieves a strong standing in Internet and Web-ApplicationServices. HP-UX 11i and Tru64 UNIX 5.1 remain in a dead heat for second

place. The two systems share the lead in System Management; and Tru64 UNIXleads in Scalability, while HP-UX occupies at least second place in all studiedareas. AIX 4.3.3 leads in Internet and Web-Application Services, but trails theRISC UNIX systems in most other areas. UnixWare 7.1.1 falls short of the RISCUNIX systems in all studied areas, suffering particular shortcomings in RAS andDirectory and Security Services.

SCALABILITYTru64 UNIX achieves the highest scalability rating, benefiting fromextraordinarily large file system and memory capacities that derive from thematurity of its early 64-bit design. Compaq tests and supports Tru64 UNIX filesystems and files up to 16 TB, while the remaining vendors support at most 1 or2 TB on their file systems. Tru64 UNIX also supports 256 GB of memory on the

AlphaServer GS320, a range that is matched only by HP-UX 11i. Tru64 UNIXrates very competitively in other key areas such as Shared-Memory

FI GURE 1: Overal l Functi onal

Ratings as of Januar y 1, 2001


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2001 UNIX Function Review SS, March 2001

2 Copyright 2001 D.H. Brown Associates, Inc.

Multiprocessing (SMP) scalability, thanks to its proven database performance on32-way GS320 server hardware, and a complete set of low-level kerneloptimizations.

HP-UX 11i follows, supporting the second-highest file system range at 2 TB, and

matching Tru64 UNIX for 256 GB memory support on HPs Superdome serverhardware, which has achieved good database benchmark results on 48-way SMPconfigurations. For building web-server farms, HP-UX 11i includes a production

version of the Resonate load-balancing tool.

Solaris supports up to 128 GB of memory, and 1 TB file systems and files. AIXsupports up to 96 GB of memory and 1 TB file systems, but files can be no largerthan 64 GB. AIX occupies a strong position in HPC technical clusters and hasproven support for very high-end database clusters. Otherwise, AIX and Solarishave roughly equivalent scalability ratings. Both demonstrate particularly strongSMP capabilities, albeit succeeding by differing criteria. While Solaris has beentested with industry-standard benchmarks on SMP servers using more processorsthan any other studied system (64), AIX was able to achieve the highest results onthe same tests using the fewest processors (24).

UnixWares scalability fundamentally depends on the capabilities of the Intelserver architecture, which will not complete its transition to 64-bits until later this

year. UnixWare supports advanced enterprise servers based on current IA-32processors, including the Unisys ES7000, a mainframe-class machine. UnixWarecan be configured with up to 32 processors and up 64 GB of memory. 1 AlthoughUnixWare supports all 32 processors in ES7000, the maximum SMPconfiguration for which UnixWare has produced credible database benchmark evidence is eight processors. As with AIX and Solaris, UnixWare supports filesystems and files up to 1 TB.

RAS (RELIABILITY, AVAILABILITY, AND SERVICEABILITY)Solaris leads strongly in the RAS area, offering several functions not yet availablefrom competitors, particularly in the Dynamic Reconfiguration (DR) andPartitioning categories. 2 Solaris 8 can arbitrarily add and remove CPUs online, andis the only studied product capable of adding and removing memory online. Also,Suns Dynamic Domains function on the E 10000 server is the only availableUNIX-partitioning function that allows the hardware partitions between OSinstances to be adjusted while keeping them online. All of the other hardware

partition solutions currently require the affected partitions to be rebooted afterreconfiguration. Solaris 8 also introduces significant enhancements to themanageability of these functions with its Reconfiguration Coordination Manager(RCM), which provides a standard Application Program Interface (API) for

1 Although UnixWare remains a 32-bit system, it can exploit the extra memory in such systems using Intels Process Addressing Extension (PAE) mechanism. Normal UnixWare applications still run in a 32-bit address space, while criticalapplications and the operating system itself can use the large memory for caching purposes.

2 Suns RAS strengths at the operating-system level are orthogonal to the reliability issues it faced at the hardware level duringthe last year due to the Error-Correcting Coded (ECC) memory failures on its high-end servers.


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serve as the only stored log required for debugging purposes. This approach helpsadministrators manage the profusion of messages from a variety of sources thatpop up during day-to-day administration. AIX, HP-UX, and Tru64 UNIX alsomaintain a slight advantage over competitors due to their ability to allow patchesto be installed using two-phase commits. The other systems do not provide

formal mechanisms allowing system administrators to back out of patches byautomatically restoring software to its preexisting state if necessary.

Otherwise, differentiation has shrunk considerably in the UNIX system-management area. While early UNIX leaders were able to establish leadershipthrough a variety of features related to ease-of-use or value-added toolsfacilitating production usage, most of the studied UNIX systems now cover all of those bases well. For example, all of the systems now fully address storagemanagement, and include a Logical Volume Manager (LVM) in the base operatingsystem, which allows storage to be managed through virtual disks orvolumes made up of one or more physical disks. All studied systems alsoenable plug-and-play hardware configuration, and provide system-managementtools that are useable by administrators with a variety of skill levels. Of particularnote, all have graphic-user-interface (GUI) tools that will appear familiar to usersaccustomed to Windows PCs and therefore provide ease of use at all levels and support some level of administrative role delegation for managementfunctions that normally require broad administrative privileges. In thisenvironment, full trusted access to the entire network does not need to be grantedto every administrator nor to lower-level employees. All studied systems exceptUnixWare provide some form of a registry mechanism to keep track of software,extensions, and patches that have been installed.

Remote administration capabilities have now matured as well. All of the studiedsystems include system-management tools that have been optimized for webusage, in some cases allowing ordinary web browsers to be used as entry-points.

All of the studied systems contain some form of template installation tool, whichallows large numbers of identical servers to be configured at once using acookie-cutter methodology.

INTERNET AND WEB-APPLICATION SERVICES AIX has the lead in the Internet and Web-Application Services area. AIX offersthe broadest support for the basic protocols needed to support sophisticated webinfrastructures. Also, AIX and Solaris are the only studied systems to build HTTP

acceleration functions into their kernels. This helps to boost web-serverperformance on their respective hardware platforms. Finally, AIX and Solarisprovide the most complete support for various Enterprise Java Beans (EJB) web-application server add-ons, and share the lead for Network File System (NFS)capabilities, both supporting all possible NFS enhancements. Both also have thebest level of support for the Distributed File System (DFS).

All studied UNIX servers now achieve good interoperability with MicrosoftCIFS-based file-sharing networks. HP-UX and Tru64 UNIX break ahead of the


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Copyright 2001 D.H. Brown Associates, Inc. 5

pack for offering some level of single sign-on across their systems and WindowsNT, both providing mechanisms able to synchronize user and passwordinformation between UNIX and Windows NT security infrastructures.Otherwise, all of the systems have available ready-to-run tools (based on eitherthe Open Source Samba technology, or various proprietary mechanisms) that

match virtually all of the file- and print-sharing capabilities of Windows NT.These tools allow all systems to provide basic file- and print-sharing services toWindows clients, appearing as virtual Windows NT servers on the network. Theycan mount remote Windows NT disks, allowing UNIX applications to access datafrom them as if they were local. In addition, all support Advanced Server forUNIX add-ons, which allow them to host Windows NT Primary DomainControllers (PDCs).

In terms of Linux interoperability, Solaris 8 and UnixWare break out of the pack with the ability to actually run existing Linux binaries natively. 3 By contrast,Compaq, HP, and IBM are currently focusing on API-level compatibility withLinux, targeting developers who want to port their Linux applications to therespective UNIX systems, rather than making any effort to run existing Linuxapplications in binary form.

DIRECTORY AND SECURITY SERVICESSolaris leads in Directory and Security Services, offering the most completesupport for directory services other than LDAP. Solaris also provides Suns entireKerberos authentication mechanism for free with the base operating system,while some other systems charge a premium. Finally, Solaris also shares the leadwith Tru64 UNIX for integrating LDAP with basic operating system functions.HP-UX achieves the highest level of support for network-security functions,sharing the lead with AIX for including secure networking tools. In particular,HP-UX stands out for including real-time host-based intrusion detectionfunctions in the base operating system. Tru64 UNIX also provides strong supportfor directory services other than LDAP, but lacks native support for thePKCS#11 cryptographic hardware API. AIX also includes a Kerberos server inthe base operating system, and provides strong network-security functions, butlacks the Pluggable Authentication Module (PAM) capability of most competitors.

All of the studied systems except UnixWare support cryptographic hardware,which offloads the encryption task to special-purpose processors, boosting thescalability of secure web sites. Indeed, SCO has historically focused on supportingdepartmental and small-business applications using traditional access methods

such as terminals. UnixWare includes relatively few tools for managing enterprisenetworks or web-based infrastructures. UnixWare also offers little support forLDAP, runs the fewest non-LDAP directory services, and includes none of thestudied network security functions except for TCP/ IP wrappers.

3 Note that only the Intel X86 version of Solaris supports this function.


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TABLE OF CONTENTSEXECUTIVE SUMMARY .................. ................. ................. .................. ................. ................. ...................... ........ 1

S CALABILITY ........................................................................................................................................................1RAS (R ELIABILITY, AVAILABILITY, AND S ERVICEABILITY )........................................................................................2S YSTEM M ANAGEMENT ........................................................................................................................................3INTERNET AND W EB-APPLICATION S ERVICES ........................................................................................................4DIRECTORY AND S ECURITY S ERVICES ..................................................................................................................5

UNIX PRODUCT OVERVIEW ................. ................. ................. .................. ................. ................. .................... ... 8

AIX 4.3.3 ................. ................. .................. ................. ................. .................. .................... ................. ............... 8HP-UX 11 I..........................................................................................................................................................9S OLARIS 8.........................................................................................................................................................10TRU64 UNIX 5.1...............................................................................................................................................12UNIXW ARE 7.1.1 ............... ................. ................. ................. ................. ................. ................. ....................... ... 13

METHODOLOGY................................................................................................................................................14

SCALABILITY ....................................................................................................................................................16

S UMMARY .........................................................................................................................................................16SMP R ANGE .....................................................................................................................................................17S TORAGE S CALABILITY ......................................................................................................................................1964-B IT S UPPORT ...............................................................................................................................................20S CALABILITY C LUSTERING O PTIONS ...................................................................................................................23LOW -LEVEL OPTIMIZATIONS ...............................................................................................................................26

RAS (RELIABILITY, AVAILABILITY, AND SERVICEABILITY) ............... ................. ................ ................ ...... 28

S UMMARY .........................................................................................................................................................28COMPONENT F AILURE RESILIENCE .....................................................................................................................30DYNAMIC RECONFIGURATION .............................................................................................................................32

J OURNALING F ILE S YSTEM .................................................................................................................................33HIGH AVAILABILITY (HA) C LUSTER OPTIONS .......................................................................................................34WORKLOAD -M ANAGEMENT TOOLS .....................................................................................................................38

SYSTEM MANAGEMENT ................ .................. .................. ................. .................. .................. ................... ...... 44

S UMMARY .........................................................................................................................................................44H ARDWARE M ANAGEMENT .................................................................................................................................45OPERATING -S YSTEM M ANAGEMENT ...................................................................................................................46S OFTWARE M ANAGEMENT ..................................................................................................................................48EVENT M ANAGEMENT ........................................................................................................................................49S TORAGE M ANAGEMENT ....................................................................................................................................51REMOTE ADMINISTRATION ..................................................................................................................................52

INTERNET AND WEB-APPLICATION SERVICES...........................................................................................54

S UMMARY .........................................................................................................................................................54WEB-P ROTOCOL S UPPORT ................................................................................................................................55WEB S ERVICES .................................................................................................................................................59F ILE AND P RINT S HARING ...................................................................................................................................60J AVA S UPPORT ..................................................................................................................................................62WEB-APPLICATION S ERVER AVAILABILITY ...........................................................................................................63W INDOWS NT INTEROPERABILITY .......................................................................................................................64LINUX INTEROPERABILITY ...................................................................................................................................66


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DIRECTORY AND SECURITY SERVICES........................................................................................................68

S UMMARY .........................................................................................................................................................68DIRECTORY S ERVICES .......................................................................................................................................69P LUGGABLE S ECURITY .......................................................................................................................................71S ECURE NETWORKING TOOLS ............................................................................................................................71

CRYPTOGRAPHIC H ARDWARE S UPPORT .............................................................................................................73


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UNIX PRODUCT OVERVIEW

AIX 4.3.3

AIX was the first major second-generation UNIX product to ship after Sun andHP established its UNIX beachheads in the 1980s. AIX was also the first systemthat had a design focus of fusing open systems advantages with traditionalproduction quality values, of which IBM had plenty to draw from its supremelyestablished mainframe business. Moreover, unlike some earlier attempts atcommercial-grade UNIX, AIX did not sacrifice functionality, modularity,manageability, or efficiency in order to gain standards conformance and openness.

After enduring a few painful early years while its implementation matured, AIXmanaged to seize a significant functional lead thanks to the strength of itsfoundation a lead it was able to maintain until D.H. Brown Associates, Inc.s(DHBAs) most recent UNIX function study in early 2000.

AIX is now in a period of transition. As before, the current version of AIX,release 4.3.3, is exclusively available on PowerPC hardware from IBM and OEMpartners such as Groupe Bull. However, in November 2000, IBM also beganshipping an early adopters release of AIX 5L, which is the first version of AIX tosupport platforms other than IBMs Power-based hardware. That version alsoruns on systems based on Intels upcoming 64-bit Itanium processor, puttingIBM in a strong position to seize an early lead on IA-64 with a production-gradeUNIX system available on the day of shipment. To develop AIX 5L, IBM allieditself with Santa Cruz Operation (SCO) in 1998 to develop an enterprise-gradeUNIX implementation for Itanium that would compete with IA-64 UNIX

versions promised from Sun and HP for the enterprise-server market. 4 Theproject with SCO involved porting IBMs new 64-bit kernel based on AIX to IA-64, endowing it with a number of user-level features from the UnixWareenvironment, and then porting the result back to PowerPC. SCO will not ship its

version of the Monterey code until IA-64 hardware begins to ship in volume,focusing instead on fusing the current UnixWare implementation with Linux aspart of its Linux Kernel Personality (LKP) initiative.

IBM will ship the new version, called AIX 5L Version 5.1, in full production inthe spring of this year. Many new functions and features of AIX 5L Version 5.1will be exploited when IBM begins shipping its next-generation high-end serverhardware in the fall.

4 See Technology Trends, SCO Jumps to AIX for IA-64, D. H. Brown Associates, Inc. October 26, 1998.


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HP-UX 11iHP has long been a leading supplier of commercial UNIX solutions, succeedingin part by emphasizing business-oriented factors such as quality, investmentprotection, consulting abilities, and support. In the 80s, HP was one of the first

major vendors to envision the market potential of an enriched and robust UNIXoperating system and to adopt it as its strategic business platform. As early as1988, HP launched a mainframe alternative initiative, persuading independentsoftware vendors (ISVs) of selected vertical markets (hospitality, for example) toco-develop versions of their software for the HP-UX platform.

After adding volume-oriented solutions based on Intel X86 servers and WindowsNT to its strategic focus, HP has recently redoubled its UNIX efforts as it seeksto provide a leading-edge operating environment for its newly-introduced high-end Superdome servers. HP also seeks to position HP-UX as the preferredenterprise UNIX for next-generation commodity servers based on IA-64, and will

introduce a version for its Itanium systems as soon as they become available. HPbelieves that it has a better chance of becoming the de-facto high-end UNIXstandard by virtue of its total focus on the IA-64 platform. While IBM willcontinue offering separate UNIX solutions based on Power and Intelarchitectures going forward, and Sun has minimized its marketing efforts to driveSolaris on the Intel platform, 5 HP will transition all of its servers from the PA-RISC architecture to IA-64 over time. Moreover, during the migration to IA-64,HPs users can take advantage of the binary compatibility with PA-RISC that HPmanaged to introduce in the IA-64 processor architecture early on, which willhelp to minimize disruption.

Due in part to its focus on the needs of business users, HP has a history of introducing advanced UNIX functions conservatively in HP-UX, optimizinginstead for criteria such as stability and investment protection . But with HP-UX 11i,announced in July 2000, HP clearly showed its seriousness about pushing HP-UXtechnically, including a burst of competitive tactical features in the newest release.HPs consistent adoption of mainframe development and deployment disciplines,and implementation of mainframe-like functions in HP-UX have clearly paid off.

A number of advanced HP-UX 11i features, such as memory-failure resiliencyfunctions and strong workload-management tools, provide particular advantagesin addressing the requirements of new web applications, clicks-and-mortarusers trying to migrate their operations to web infrastructures, and traditional-enterprise IT environments.

HP has also invested in simplifying the packaging for HP-UX. Instead of requiringusers to order and install HPs software options on an individual basis, HP offerspreconfigured Operating Environment packages of the HP-UX 11i base operatingsystem and key add-ons for different application requirements (see Table 1).

5 However, Sun has continued developing the Intel X86 version of Solaris, which includes almost all of the features in the

SPARC version. Moreover, as a result of offering the Intel X86 version of Solaris 8 for free via web download (or minimalmedia costs), Sun was able to build a base of more than 400,000 registered users for that product.


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TABL E 1: Overview of H P-UX 11i Pack age Contents

HP-UX 11iOperating Enviro nment

(Base Package)

HP-UX 11iEnterprise

Operating Environment

HP-UX 11iMission Critical

Operating Environ ment

HP-UX 11iTechnical Computin g

Operating Environment

HP-UX 11i core functions(including 32-bit and 64-bit HP-UX kernels)

EMS Framework

ObAM5

Partition Manager

Software Distributor

Apache Web Server

CIFS/9000 Server

CIFS/9000 Client Java JPI

Java RuntimeEnvironment

Netscape Communicator

PAM Kerberos

ServiceControl Manager

EMS HA Monitors MirrorDisk/UX

Online JFS (v3.3)

OV GlancePlus

Process ResourceManager

Plus all functions inHP-UX 11i baseOperating Environment

ECM Toolkit MC/ServiceGuard

ServiceGuard NFS

Workload Manager

Plus all functions in HP-UX 11i Mission CriticalOperating Environment

3D Graphics Apache Web Server

CIFS/9000 Server

CIFS/9000 Client

FirstSpace VRML Viewer

Java 3D

Java JPI

Java RuntimeEnvironment

MLIB

MPI

Netscape Communicator

PAM Kerberos

Visualize Conference

SOLARIS 8Sun originally made UNIX fashionable. After establishing itself as a leadingsupplier of high-performance workstations during the 1980s and early 1990s, Sunshifted its strategic goal to becoming a first-tier vendor of enterprise servers.While such a major strategic transformation would be risky for any company, Sunmanaged to overcome the challenge with considerable success, benefiting fromthe confluence of three major forces: Sun maintained a total focus on UNIX and SPARC at a time when most

other UNIX vendors strayed to Windows NT and Intel X86 architectures.These other vendors were caught off guard when functional gains forWindows NT and Intel X86 servers materialized more slowly than expected,

just as the surge in web usage and e-business requirements introduced adramatic new need for reliability and scalability, which commodity systemscould not meet. Also, in an adroit and remarkably successful response to theencroachment of the Wintel juggernaut, Sun kept its SPARC serverscompetitive at the low-end of the server market a space that most other

vendors left to commodity systems running Windows NT. Sun accomplishedthis by embracing and extending the characteristics of PC servers as much aspossible in its SPARC-based workgroup-server hardware, adopting similarcomponent and manufacturing technologies that minimized the pricing


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premium of its proprietary platform. As a result, Solaris now enjoys a uniquebenefit amongst UNIX systems: it provides a single line of binary-compatibleplatforms that span the range from very price-competitive low-end serversand workstations up to clusters of high-end, mainframe-like SMP servers. Bycontrast, most of the other vendors fragment their product lines across

commodity servers running Windows NT or Linux at the low-end, and RISC-based UNIX systems at the high-end, thus sacrificing binary compatibility. In 1997, Sun gained a three-year head-start over its competitors for bringing

several key mainframe-like functions into the UNIX space when it introducedthe Enterprise 10000 server. Suns lead came about as a result of anastonishing stroke of fortune in 1996 when it acquired the Business SystemsDivision (BSD) of Cray Research, which had designed the StarFire system.Based on SPARC and Solaris, StarFire had very high-end SMP capabilities.Solaris exploited these capabilities handily thanks to design choices that hadbeen forced by hardware conditions a few years earlier. 6 These included aleading-edge RAS feature developed by Cray called Dynamic Domains, which

remains the closest comparable function to mainframe Logical Partitions(LPARs) that is currently available for UNIX. Even now, few of the leadingUNIX suppliers have matched the E 10000s SMP range, and none have yetfully matched Suns Dynamic Domains function. Coupled with Sunslegendary marketing prowess, the E 10000 earned the company extraordinary

visibility in traditional IT datacenters at a time when interest in high-endUNIX systems was beginning to surge.

Simultaneously with its efforts at the systems level, Sun gained significanttraction in the enterprise middleware space with its Java technology. Java hasbeen adopted by a broad set of vendors and IT managers. While Javaoriginally received much attention as a platform for neutralizing the barriers

between client platforms, it has proven to be an effective mechanism fordeveloping server-side applications as well. By investing in value-added serversoftware options based on Java from iPlanet, Sun has strengthened its abilityto provide an end-to-end solution for critical server infrastructures based onSolaris.

Sun announced Solaris 8 in November 1999 and began shipping the new systemin early 2000. However, many of the critical layered software products for Solaris,including Sun Cluster and PC/ NetLink, did not begin shipping on Solaris 8immediately. 7 Now, Sun has not only shipped the entire Solaris 8 product set, buthas also delivered key enhancements to some of those layered options, includingshipment of a major update to its HA clustering capabilities with Sun Cluster 3.0in November 2000. Although Sun has yet to ship the long-awaited midrange and

6 When Solaris 2 began shipping, Suns SuperSPARC processor was trailing most competing RISC processors in performance.

Sun responded by investing heavily in developing SMP capabilities for its workstations and servers. As part of the effort,Solaris was optimized for SMP earlier than most other UNIX systems. For example, Solaris was the first major RISC-basedUNIX system to introduce sophisticated kernel-thread mechanisms for optimizing applications.

7 DHBAs previous UNIX Function Review covered Solaris 7, even though Solaris 8 had already been announced at the timeof publication. See 1999-2000 OperatingSystemFunction Review , D.H. Brown Associates, Inc., March 2000.


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high-end server hardware based on its next-generation UltraSPARC III processor,it is currently positioned very well from a UNIX-system software standpoint.

TRU64 UNIX 5.1

Tru64 UNIX derives from a long and sometimes contentious relationshipbetween UNIX culture and Digital Equipment Corporation, which Compaqpurchased in early 1998. UNIX was born and bred on Digital hardware in the1970s. AT&T and universities mostly drove UNIX development, but Digitalalways maintained a UNIX group to develop and support drivers as well as to testnew designs on UNIX. Digital eventually released ULTRIX, which was UNIXimproved by clearer documentation, enhancements specific to Digital hardware,and support services.

Digital continued to develop its VAX/ VMS systems while universities and AT&Tcontinued to develop UNIX, and all vendors waged the UNIX Wars, which

lasted through multiple standardization attempts. As industry began to use UNIXmore, Digital, along with other vendors, funded efforts such as the X WindowSystem, the Open Software Foundation (OSF) initiative, and also played an earlyrole in the creation of Linux by donating resources and equipment so that Linuxhad a native Alpha port by 1994.

Digital responded to a perceived lack of commitment to UNIX by leapfroggingits competition with overwhelming technical force. The company introducedblistering performance with its 64-bit Alpha RISC processor and 64-bit UNIX.Tru64 UNIX became the first in the industry to move to 64 bits and used animplementation based on state-of-the-art OSF/ 1 operating-system technology.Strictly in terms of technology, the investments have clearly paid off well. Alpharoutinely resides in the leading position for processor performance, and Tru64UNIX has consistently stayed at the head of the pack for operating systemfunctions.

Compaq has continuously maintained its investment in Alpha UNIX products,recognizing that to be considered a credible enterprise player, it needs to balanceits burgeoning commodity PC business with differentiated proprietary offerings.Extending its product line to the high end of the UNIX space, Compaq finallyshipped the 32-way AlphaServer GS320 (formerly code-named Wildfire) lastsummer, accompanied by a steady stream of functional improvements in Tru64UNIX V5.1, released in the fall of 2000.

Today, Compaqs Alpha UNIX business is focused on five strategic markets:Business Intelligence, High Performance Technical Computing, Telco andInternet Applications, and Enterprise Applications. Within the past year, therehave been several impressive, high profile wins in these segments, such as thePittsburgh Supercomputing project in HPTC, and Ericsson in Telco.


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UNIXWARE 7.1.1Santa Cruz Operation (SCO) historically dominated the UNIX-on-Intel marketwith over 85% of marketshare and a deep understanding of the platform. SCOachieved its position through its long-standing OpenServer product. This product

generated a respectable set of third-party solutions for meeting small-businessrequirements. More important, SCO gained expertise in supporting the vast anddiverse array of hardware that permeates the Intel X86 landscape, offering acompetency matched only by Microsoft. In recent years, SCO has focused on themore advanced UnixWare, which it acquired from Novell in 1996. UnixWare isan implementation of System V Release 5 (SVR5) with PC-oriented networkingextensions, integrated Internet connectivity, and enhancements targeting reliabilityand scalability.

UnixWare 7 allowed SCO to make the leap from targeting small-to-medium-sizedbusinesses to become a serious UNIX competitor, poised to take on enterprise

requirements. However, despite its early success in lining up OEM partners, SCOwas unable to continue the investments in UnixWare required to compete withthe heavyweight UNIX systems from Sun, HP, IBM, and Compaq. SCOannounced in late 1998 that it would no longer position UnixWare as anenterprise platform when IA-64 arrived, choosing instead to embrace the AIXkernel as the foundation for the next-generation Monterey product.

Since then, SCO took a step further and announced that it would sell all of itsUNIX products, including OpenServer and UnixWare, to Caldera Systems Inc., aleading Linux-distribution supplier. The transaction has not yet been completed, 8but Caldera has stated that it will sustain SCOs efforts to enhance UnixWare forIA-32 platforms, which will remain relevant for some time until IA-64 entersmainstream markets. Caldera also plans to introduce a Linux Kernel Personality(LKP) for UnixWare that will allow it to run Linux applications. Caldera plans toposition UnixWare as a kind of super-charged Linux environment that is fullycompatible with other Linux distributions, but has more powerful functionsunder the hood than the traditional Linux kernel. To deliver on this promise,however, Caldera will have to marshal sufficient development resources to keepup with the investments of the established enterprise competitors.

8 The acquisition is due to be completed by second quarter 2001.


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Quality : As with any other complex technical product, an operating systemmay ship with a number of defects, which are independent of its relativetechnical richness. Formal methods to measure quality vary from stress testingto collecting empirical data based on customer-satisfaction surveys.

Vendor Support : At the high end of software complexity, operating systemsintroduce a notoriously high support burden, especially when deployed onservers. The ability of vendors to meet those support requirements may vary.

Vendor Experience : Vendors offering multiple operating systems may havedifferent levels of experience within their respective product lines, dependingon when they entered the market and with what level of commitment.

Skills Availability : This factor applies both to the skills available within a usersorganization and in the market as a whole.

Hardware/ SystemCapabilities : Since an operating system will only perform aswell as its underlying hardware, users must remain aware of factors such asprocessor performance and the SMP ranges available on host platforms.

Cost : A complex and contentious area, this factor depends not only onoperating-system software prices and associated client license fees, but also onany necessary add-on packages, the price and price/performance of underlying hardware, and a wide variety of hard-to-measure soft costsrelated to ongoing management and training.


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SCALABILITY

5.50 6.00 6.50 7.00 7.50 8.00 8.50 9.00

UnixWare 7.1.1

AIX 4.3.3

Solaris 8

HP-UX 11i

Tru64 UNIX 5.1


FIGURE 2: Scalability Ratings

SUMMARY

All five of the systems rank in the Good to Very Good categories. Tru64UNIX receives the highest scalability rating, benefiting from extraordinarily largestorage and memory capacities that derive from the maturity of its early 64-bitdesign. Compaq tests and supports Tru64 UNIX file systems and files up to 16TB, while the remaining vendors support at most one or two TB on their storagesystems. Tru64 UNIX also supports 256 GB of memory on the AlphaServerGS320, a range that is matched only by HP-UX 11i. Tru64 UNIX now also rates

very competitively in other key areas such as SMP scalability, thanks to its provendatabase performance on 32-way GS320 server hardware, and a complete set of low-level kernel optimizations.

HP-UX 11i follows, supporting the second-highest file system range at 2 TB, andmatching Tru64 UNIX for 256 GB of memory support on HPs Superdomeserver hardware, which has achieved good database benchmark results on 48-waySMP configurations. For building web-server farms, HP-UX 11i includes aproduction version of the Resonate load-balancing tool.

Solaris supports up to 128 GB of memory, and 1 TB file systems and files. AIXsupports up to 96 GB of memory and 1 TB file systems, but files can be no largerthan 64 GB.

AIX achieves a strong position in High Performance Computing (HPC) technicalclusters and proven support for very high-end database clusters. Otherwise, AIXand Solaris have roughly equivalent scalability ratings. Both have particularlystrong SMP capabilities, albeit succeeding by differing criteria. While Solaris hasbeen tested with industry-standard benchmarks on SMP servers using moreprocessors than any other studied system (64), AIX was able to achieve thehighest results on the same tests using the fewest processors (24).

UnixWares scalability fundamentally depends on the capabilities of the Intel-server architecture, which will not complete its transition to 64-bits until later this

FI GURE 2: Scalabil it y Rati ngs


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year. UnixWare supports state-of-the-art enterprise servers based on current IA-32 processors, including the Unisys ES7000, a mainframe-class machine that canbe configured with up to 32 processors and up to 64 GB of memory. 9 AlthoughUnixWare supports all 32 processors in ES7000, the maximum SMPconfiguration for which UnixWare has produced credible database-benchmark

evidence on is eight processors. Like AIX and Solaris, UnixWare supports filesystems and files up to 1 TB.

SMP Range30%

64-BitSupport

20%

StorageScalability

25%

Low-LevelOptimizations

10%

ScalabilityClustering

Options15%

FIGURE 3: Scalability Criteria and Weightings

SMP RANGEShared-Memory Multiprocessing (SMP) boosts system performance by harnessingmultiple processors within a single server that all share the same memory and I/ Oresources. Because SMP incurs fewer penalties related to management andprocessing overhead than other multiprocessing techniques, and is also relativelyeasy for application developers to exploit in their code, it remains one of the mosteffective ways to increase system performance for many key business applications,including database servers and Online Transaction Processing (OLTP) functions.

Since all processors in an SMP server must be able to access all system resourcessimultaneously, operating systems are deeply involved in the quality of an SMP

implementation. Indeed, enabling a kernel to effectively manage large numbers of processors has traditionally presented an extraordinary and tedious challenge foroperating-system developers. Typically, hardware and software design teams mustcooperate closely and consider a variety of factors throughout the system,including memory-bus bandwidth and cache sizes, to optimize theirimplementation. Moreover, they must gather huge amounts of empirical data to

9 Although UnixWare remains a 32-bit system, it can exploit the extra memory in such systems using Intels Process

Addressing Extension (PAE) mechanism. Normal UnixWare applications still run in 32-bit address space, while criticalapplications and the operating system itself can use the large memory for caching purposes.

FI GURE 3: Scalabil it y Criteri a

and Weighti ngs


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0

50

100

150

200

250

AIX HP-UX Solaris Tru64 UNIX UnixWare

t p m

C ( t h o u s a n

d s )

0

8

16

24

32

40

48

56

64

C P U s

tpmC (x1000) CPUs

Oracle 8i Oracle 8 Sybase ASE Oracle 8.1.7 Oracle 8i

Source: Transaction Processing Council (www.tpc.org)FIGURE 4: Maximum TPC-C Results vs. Processor Range by Operating System/ Database

AIX stands out for reaching the highest TPC-C result of all studied UNIXsystems (220,807 tpmC) on SMP hardware. Moreover, AIX was able to achievethese results using the fewest processors (24). By contrast, Solaris required 64processors to deliver competitive results, due in part to the lagging performanceof Suns UltraSPARC II processor and the aging design of its E 10000 server.

Note, though, that Solaris ability to manage more processors under benchmark conditions than any other studied system bodes well for a performance surgewhen high-end servers based on Suns more powerful UltraSPARC III processorarrive later this year.

UnixWare supports up to 32 processors in SMP systems, but very few Intel X86-based servers currently support more than eight processors. TPC-C results forUnixWare have only been produced on an eight-way server (41,085 tpmC on theUnisys ES2085R). However, Unisys recently began shipping a 32-way ES7000server that supports UnixWare, so more competitive results may well appear inthe future.

STORAGE SCALABILITYStorage consumption has surged dramatically with the growth of the web, as datastores have evolved from passive receptacles into active participants in the ITinfrastructure. Storage hardware developers have responded with highly scalabletechnologies such as Storage Area Networks (SANs) and Network AttachedStorage (NAS). To fully support these devices, operating systems need to manage

FI GURE 4: Max imum TPC-C

Results vs. Processor Range by Operati ng

System/ Database


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file systems and files that range far beyond the 4 GB originally permitted by 32-bitsystems.

All of the studied environments support large file systems, and provide thenecessary base operating system functions and Application Program Interfaces

(APIs) to support 64-bit files, through which properly written applications cantheoretically access up to 16 exabytes (EB) of data. However, the studied systems vary in terms of the storage configurations that their vendors actually test andsupport, resulting in some differentiation in terms of their practical storagescalability (see Table 2).

TABLE 2: Maximum Tested/Supported File System and File SizesTru64 UNIXs storage scalability clearly benefits from Compaqs early leadershipin 64-bit technology. Compaq supports file systems and files ranging up to 16 TBon its AlphaServers running Tru64 UNIX, much more than any other vendor.HP follows, supporting 2 TB file systems and files on PA-RISC systems runningHP-UX. IBM, Sun, 10 and SCO each support file systems up to 1 TB on theirrespective servers. Sun and SCO support files up to 1 TB as well, while AIX 4.3.3is limited to 64 GB files.

64-BIT SUPPORTSupport for 64-bit processing can deliver significant benefits for certain types of commercial applications, primarily those that depend on large databases, whichcan use direct 64-bit memory access to cache entire database indexes (or even thedatabase contents themselves) in physical memory, thus cutting access time by anorder of magnitude of two over queries requiring disk access. However, becauseeven database applications do things other than queries (and because disk I/ O istypically overlapped, buffered, and cached by the operating system), performanceimprovements in real-world situations with real workloads may provesubstantially more modest. For example, the benefit to TPC-C results for various64-bit vendors has typically been closer to a factor ranging from 10% to two

times.

Indeed, benefits deriving from switching to a 64-bit architecture are quite differentand less obvious than those stemming from the previous microprocessorevolutions. Widening the internal and external data paths from 8 to 16 and finally to

10 For applications that need to manage more storage, Sun directs its users to the Veritas VxFS file system, a third-party option

that supports greater ranges. Veritas v3.4 supports file system sizes up to 2 TB. To minimize the burden on the user forobtaining and managing the Veritas option, Suns VOS (Veritas, Oracle, Sun) program involves joint engineering work among Veritas, Oracle, and Sun to get Veritas and Oracle ready the first day on every release of Solaris.

File System Size File Size

Tru64 UNIX 5.1 16 TB 16 TB

HP-UX 11i 2 TB 2 TB

Solaris 8 1 TB 1 TB

UnixWare 7.1.1 1 TB 1 TB

AIX 4.3.3 1 TB 64 GB

TABLE 2: M axi mum Tested/

Supported Fi le System and Fi le Sizes


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32 bits wide had a direct impact upon speed because fewer cycles were requiredto transfer a typical 32-bit word that contained either a floating-point quantity or aninstruction containing a complete memory address. Because most of the individualdata items or instructions are no more than 32 bits (even with the newarchitectures), the benefits of a 64-bit data path are less apparent.

In general, operating systems can provide 64-bit capabilities at three incrementallevels: Run on 64-bit processors such as Alpha, MIPS, PA-RISC, PowerPC, or

UltraSPARC. Support largephysical memory , i.e. real memory greater than four GB. Provide large virtual memory, which allows applications to run in a 64-bit

process address space. Only operating systems with this capability qualify asfull 64-bit processing environments.

AIX, HP-UX, Solaris, and Tru64 UNIX have all run natively on 64-bit processorsfor years, and have been fully tuned and optimized for their respectiveenvironments (see Table 3 below). Of this group, Tru64 UNIX has the mostmature 64-bit implementation, while Solaris introduced its full 64-bit capabilitiesmost recently of the studied RISC systems. HP-UX and AIX each havemoderately established 64-bit implementations. However, AIX 4.3.3 provides a64-bit application environment on top of a 32-bit kernel. While thisimplementation allows AIX to support older 32-bit device drivers in a 64-bitenvironment, it also causes some 64-bit applications to endure a smallperformance penalty at very high transaction rates for checking, reshaping, andcreating internal kernel data structures.

UnixWare currently lacks full 64-bit capabilities, since it only runs on serversusing the 32-bit Intel X86 architecture. Intel is scheduled to introduce its 64-bitIA-64 architecture later this year with the Itanium processor. Future versions of UnixWare will exploit the capabilities of the Itanium. 11

TABLE 3: Relative Maturity of 64-Bit Hardware Support

11 These versions will be based on the Monterey technology co-developed with IBM, which is based on the AIX kernel.

64-BitProcessor

64-Bit HardwareIntroduced

Full 64-Bit Address ing Introduced

Tru64 UNIX Alpha 1992 1992

HP-UX PA-RISC 1996 1997

AIX PowerPC 1994 1997

Solaris Solaris 1995 1998

UnixWare IA-64 2001 2001

TA BLE 3: Relati ve Maturi ty of 64-

Bi t H ardware Support


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Since the RISC-based UNIX systems are now all fully 64-bit enabled, they easilysupport memory ranges far beyond the 4 GB limit imposed by 32-bit hardware.However, the systems vary in terms of the large memory configurations vendorsactually test and support with their hardware, resulting in some differentiation interms of practical processing scalability that can vary considerably from

theoretical limits (see Table 4).

* Fujitsu GP7000

TABLE 4: Maximum Physical Memory SupportedHP-UX and Tru64 UNIX support the largest amount of physical memory of allstudied systems, managing 256 GB on HPs Superdome and Compaqs

AlphaServer GS320 hardware, respectively. Solaris follows, supporting 128 GBon Fujitsus GP7000 server and 64 GB on Suns own E 10000 server, while AIXsupports 96 GB, the maximum physical memory available for IBMs servers.

Although current Intel X86 processors all have 32-bit instruction sets, newerPentium Pro and Pentium II Xeon processors support 36-bits of real memorythrough Intels Physical Address Extensions (PAE). UnixWare exploits PAE,allowing it to manage up to 64 GB of physical memory. 12

When moving to 64-bit operating systems from their earlier 32-bitimplementations, concerns sometimes arise related to compatibility with existing32-bit applications and device drivers. Indeed, in some cases, these concerns haveslowed the adoption of newer 64-bit operating systems, despite their offeringadvanced functions in other areas. Tru64 UNIX and HP-UX have largelyovercome their migration hurdles, with most of their key applications and devicedrivers having made the leap to 64-bits. The transition remains a work-in-progressfor IBM and Sun, however. IBM is shipping a new 64-bit kernel in AIX 5L, whichrequires existing 32-bit device drivers to be recompiled before they can be used, 13and many Solaris users still run the 32-bit 2.5.1 and 2.6 versions. Since the 64-bittransition will not truly begin for UnixWare until Intels Itanium processor ships

later this year, its future backwards compatibility with 32-bit applications anddevice drivers still remains unclear.

12 UnixWare can manage more than 4 GB of memory despite the fact that its applications have only 32-bit addressing

available, by providing special APIs for use by appropriate applications. For example, specially modified database systemscan use the extra physical memory to cache data that would otherwise reside on disk, boosting performance transparentlyfor 32-bit applications accessing the database.

13 One luxury of the 32-bit/ 64-bit hybrid kernel approach used in earlier versions of AIX was backwards-compatibility for 32-bit device drivers.

Maximum PhysicalMemory Supported

64-Bit Address ing Supported

HP-UX 11i 256 GB Yes

Tru64 UNIX 5.1 256 GB Yes

Solaris 8 128 GB* Yes

AIX 4.3.3 96 GB Yes

UnixWare 7.1.1 64 GB No

TA BLE 4: M axi mum Physical M emory Support ed


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SCALABILITY CLUSTERING OPTIONSClusters can be used to increase system capacity, including performance andstorage, for some types of applications. To scale performance on a cluster,applications work in concert with clustering software to partition their workloads

into subtasks, which the clustering software then distributes across the clusteredservers. However, since even the fastest cluster interconnects usually have lowerbandwidth and greater latency than the bus in an SMP system (in some cases byseveral orders of magnitude), synchronization among the subtasks becomes acritical bottleneck that systems must minimize. Identifying opportunities forcoarse-grained parallelism proves key to effective scalability on clusters. A varietyof parallel programming tools and techniques have emerged to assist inpartitioning applications for clusters. Their use requires considerable expertisethough, and some classes of applications fundamentally cannot be adapted at all.If sufficiently partitioned, applications can exploit clustered systems containinghundreds or even thousands of nodes, delivering monumental gains in

performance.Performance clustering options typically fall into one of three broad categories: High-PerformanceComputing(HPC) Clusters address some of the worlds deepest

computational problems, including simulation of natural phenomena, finiteelement analysis, and mechanical design. While most HPC applications fallinto the engineering and scientific domain, HPC is increasingly penetratingbusiness computing as well, where it can be employed for sophisticatedfinancial analysis algorithms. Most HPC-application designs have convergedaround two public-domain parallel-processing packages, Message-PassingInterface (MPI) and Parallel Virtual Machine (PVM), which handle dispatch,

collection, and management of processing tasks across cluster nodes. DatabaseClusters boost transaction throughput by spreading workload acrossmultiple instances of a database server running in parallel. While most OLTP-oriented tasks tend to scale better on SMP systems, which suffer a much lesssevere penalty with regard to inter-processor communication, a fewcommercial applications rely on analysis as well and thus lend themselves wellto cluster deployment. For example, data warehousing involves scanning largedatabases for patterns that can be used to help make business decisions(decision support is typically cited as a key benefit of data-warehousingapplications). Many classes of data-warehousing applications can partitiontheir data sets so as to minimize inter-node synchronization, allowing them to

achieve good scalability on clusters. However, data partitioning anddistribution must be implemented at the core of a database engine to work effectively, meaning that database systems require modifications to properlysupport clustered operation. Several commercial database systems, includingOracle Parallel Server (OPS), IBM DB2 Universal Database (UDB), andInformix XPS, have been extended to work in parallel on clusters of serversconnected by high-speed interconnects.

Web-Server Farms (IP clusters) allow ISPs or corporate Intranet sites to map allthe traffic destined for a single website (i.e., home.netscape.com) to a


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farm of multiple web servers across which the Internet traffic is balanced.IP clustering can take place either in hardware, at a router-like device sitting infront of the web-server farm, or in software, on a separate server that sits infront of the web-server farm. These techniques allow operating systems tosupport the largest websites on the Internet, some of which have to process

millions of hits per day, which can exceed the capabilities of a single server.

AIX, HP-UX, Solaris, and Tru64 UNIX all support the necessary tools to developHPC clusters, including native versions of Message Passing Interface (MPI) andPVM, along with value-added utilities that simplify management of clusters forscientific-computing applications. However, the studied systems still varysignificantly in terms of the degree to which they are actually deployed in HPC-cluster environments. This divergence may result from a variety of factors that areindependent of operating-system capabilities, including vendor focus, hardwareperformance and price/ performance. But the mindshare established for aplatform has a significant effect on its credibility as an HPC environment, since itaffects application availability and access to expertise. One key indicator of thedegree to which the studied environments have penetrated the HPC space can befound in the list of the worlds 500 most powerful computer systems that hasbeen compiled by the TOP500 organization 14 twice a year since 1993 based onthe LINPACK benchmark. LINPACK measures peak Floating Point OperationsPer Second (FLOPS).

AIX43% Tru64 UNIX

2%

HP-UX1%

Solaris16%

Other 38%

Highest rank: #1

Highest rank: #31

Highest rank: #91

Highest rank: #133

FIGURE 5: UNIX Operating System Representation in TOP500 SupercomputerSites (November 2000)

14 See http:/ / www.top500.org

FI GURE 5: UN I X Operati ng System

Representat ion in TOP500 Supercomputer Si tes

(N ovember 2000)


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Shown above is the UNIX operating system representation among the TOP500sites. IBM dominated the November 2000 TOP500 15 list, capturing the numberone performance slot and representing 43% of all 500 entries with systemsrunning AIX (see Figure 5). Solaris has the next highest representation in the list,running on 16% of all entries and delivering the 133rd-highest performance.

Systems running HP-UX and Tru64 UNIX reach higher performance levels(number 91 and 31, respectively), but have relatively insignificant representationoverall at 1% and 2%, respectively. UnixWare is not represented on the list .

Both Sun and Compaq have redoubled their efforts to grow their share of theHPC market. Solaris 8 supports Suns recently acquired GridWare technology,which provides a sophisticated toolkit for taking advantage of contributedprocessing cycles from large numbers of heterogeneous systems.

Compaq has also stepped up the pursuit of high-end supercomputer applicationswith its TruCluster technology, and has captured several key accounts byhighlighting its superior ability to manage HPC-cluster resources. For example,the U.S. Department of Energy (DOE) announced that Compaq would providethe project technology for a Cooperative Research and Development Agreementbetween Sandia National Laboratories and Celera Genomics, which will build a100 TeraOPS (trillions of operations per second) supercomputer. The DOENational Nuclear Security Administration (NNSA) selected Compaq to buildwhat is expected to be the worlds fastest and most powerful supercomputer. TheNational Science Foundation selected Compaq and the PittsburghSupercomputing Center to build and manage the worlds largest supercomputerfor nonmilitary, scientific applications. Compaq AlphaServer systems runningTru64 UNIX played a critical role in Celeras mapping of the human genome, aswell as at the two largest sequencing centers supporting the public HumanGenome Project. The French Atomic Energy Commission (CEA) recentlyselected Compaq to build the largest supercomputer in Europe.

AIX, HP-UX, Solaris, and Tru64 UNIX all support the leading parallel-databaseservers including IBM DB2, Informix XPS, and Oracle Parallel Server (OPS).Further, Compaq, IBM, and Sun have each boosted their credibility in parallel-database environments by validating cluster configurations of their operatingsystems with industry-standard benchmarks such as TPC-H and TPC-C (seeTable 5). IBM stands out in particular for pushing its DB2 clusters up to 32 nodeson AIX.

15 See IBM Dominates TOP500 , D. H. Brown Associates, Inc., December 2000.


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TABL E 5: Database Cluster Benchmark Results for UN I X Operati ng Systems

OS Hardware Database # Nodes CPUs/ Node Benchmark Date Result

AIX RS/6000 SP 550 DB2 UDB 32 4 TPC-H 4/27/00 12,867 QphH

Tru64 UNIX AlphaServer GS140 Informix XPS 8 8 TPC-H 11/1/99 6,514 QphH AIX RS/6000 S70 OPS 5 12 TPC-C 6/30/99 110,434 tpmC

Solaris Enterprise 6500 Oracle 8i 4 24 TPC-C 9/24/99 135,461 tpmC

All of the studied operating systems can be deployed in concert with hardware-based web-server farm solutions such as Cisco LocalDirector, which takesincoming Internet Protocol (IP) sessions and rewrites the IP headers of a packetstream to redirect them to a particular server. The process uses a technique calledNetwork Address Translation, defined in RFC 1631. This approach requires nochanges to DNS configurations and only minimal configuration of web servers,other than to insure that the web servers have mirrored data or are operatingfrom a common network-based file store. Hardware-based solutions can balancea broad range of TCP/ IP-based functions beyond web services, including e-mailor FTP.

However, even though hardware-based web-server farm solutions work well andare widely used, their deployment can be expensive, particularly since a secondbackup unit is typically needed to avoid a single point of failure. Also, hardware-based load-balancing approaches do not necessarily have the ability to dynamicallybalance IP connections according to the load on each server in the web-serverfarm. Software-based IP load-balancing options such as iPlanet Proxy Server orResonate Central Dispatch can be more flexible in this regard. While most of

these tools are available for the studied UNIX systems, HP-UX stands out forbundling the Resonate tool with a license to manage up to three servers.

Tru64 UNIX and UnixWare offer somewhat limited support for traditional web-server farm options iPlanet Proxy Server and Resonate support neitherplatform. Instead, Compaq promotes load-balancing capabilities for IP servicesusing its TruCluster HA clustering package, a technique that is also supported inSun Cluster and UnixWare NonStop Clusters. These approaches also pass on thebenefit of HA failover to other types of services.

LOW-LEVEL OPTIMIZATIONSOver the years, UNIX operating-system developers have introduced a variety of low-level optimizations that can boost performance in certain types of applications. For example, all of the studied UNIX systems now support kernel-based asynchronous I/ O , which allows applications to continue processing whilewaiting for time-consuming I/ O operations to complete, and direct I/ O , whichallows critical applications to bypass the caching mechanism normally used by filesystems to manage storage access. Some differentiation remains due to otherperformance optimizations, including,


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Memory FileSystem : Some UNIX systems provide a file-system implementationthat resides entirely in virtual memory, i.e., no permanent file structures ordata are written to disk. This capability, which is referred to as /tmpfs (ortemporary file system) is available in all of the studied systems except HP-UX. 16

Dynamic Page Sizing : Historically, UNIX operating systems used fixed-sizepages to perform I/ O operations. However, some classes of applications maybenefit from variable page sizes. For example, applications that involve use of many small files (such as e-mail servers) may operate more efficiently withsmall page sizes, while I/ O-intensive applications implementing large block transfers may run better with large page sizes. Tru64 UNIX and UnixWareeach allow administrators to set I/ O page sizes by process. HP-UX supports

variable-sized virtual memory pages and dynamically adjusts the page sizesused for application to optimize performance. No administrator interventionis required.

Kernel Thread Architecture : All studied environments now support kernelthreads, which are required to effectively scale multithreaded applications onSMP systems, and enable key programming techniques such as asynchronousI/ O. While traditional kernel thread mechanisms used one-to-one (1-1)approaches in which each application thread has one corresponding kernelthread more advanced implementations employ MxN thread approaches,in which the kernel multiplexes a configurable number of user threads over afixed (but also configurable) number of kernel threads. For some applicationclasses, MxN thread-scheduling can boost efficiency, since the user threadscan avoid calling kernel functions directly, thus reducing the overhead of saving and restoring the kernel state when making those calls. An MxN threadarchitecture also allows the creation of many more user threads, because it

requires a smaller overhead per thread. All of the studied UNIX systemssupport MxN threads except HP-UX, which will introduce this capability inthe second half of 2001.

16 HP-UX 11i ships with a Memory File System that provides comparable functionality, but HP does not advertise it as a

tmpfs.


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RAS (RELIABILITY, AVAILABILITY,AND SERVICEABILITY)

5.50 6.00 6.50 7.00 7.50 8.00 8.50 9.00

UnixWare 7.1.1

AIX 4.3.3

Tru64 UNIX 5.1

HP-UX 11i

Solaris 8


FIGURE 6: RAS Ratings

SUMMARYSolaris has a strong lead in the RAS area, offering several functions not yetavailable from any competitors, particularly in the Dynamic Reconfiguration (DR)and partitioning categories. Solaris 8 can arbitrarily add and remove CPUs online,and is the only studied product that can add and remove memory online. Also,Suns Dynamic Domains function on the E 10000 server is the only availableUNIX partitioning function that allows the hardware partitions betweenoperating-system instances to be adjusted while keeping them online. All of theother hardware partition solutions currently require the affected partitions to berebooted after reconfiguration. Solaris 8 also introduces significant enhancementsto the manageability of these functions with its Reconfiguration CoordinationManager (RCM), which provides a standard API for applications to adjust onlineto changing domain configurations so that they can dynamically optimize theiruse of available resources (i.e. processors and memory). RCM also allowsreconfiguration to be automated through scripting, maximizing the ability of servers using Dynamic Domains to flexibly accommodate tasks that vary withbusiness schedules. Some key software packages, such as Oracle 9i, already exploitRCM.

HP-UX follows, offering strong functions to handle component failure, leadingresource management tools, first-class Fibre Channel support, and strong DisasterRecovery options. HP-UX is one of only two systems that can detect and recoverfrom memory errors online. HP-UX Workload Manager is the only goal-basedresource-management tool currently available. Using this product, administratorscan define targets in terms of overall application performance, rather than theperformance of any one subsystem. HP-UX is one of two systems that supportsall studied fibre channel capabilities, and HPs MC/ ServiceGuard CampusCluster,ContinentalCluster and MetroCluster packages share the lead for DisasterRecovery capabilities.

FI GURE 6: RA S Rati ngs


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Although all studied systems include a Journaling File System (JFS), only HP-UX11i and Tru64 UNIXs AdvFS file system offer Full Journaling, which applieslogging to maintain the integrity of the files themselves in addition to that of thefile system. Like HP-UX, Tru64 UNIX can scrub and correct double-bit memoryerrors online. Tru64 UNIX is also the only other system with complete support

for all studied Fibre Channel functions. Tru64 UNIX also offers the strongestCluster File System (CFS), with the only CFS implementation that works on theroot file system. For Disaster Recovery, Tru64 UNIX supports the optional DataReplication Manager (DRM), and Oracle Log Shipping. TruClusters can also useFibre Channel in place of Memory Channel, which extends cluster ranges to threekilometers.

AIX provides the most complete support for handling processor failure, andoffers particularly strong Disaster Recovery functions in its GeoRM GeographicMirroring and HAGEO wide-area failover options. AIX is also the only system tomatch the capabilities of Suns Live Upgrade feature, which allows installation of an operating-system image to occur simultaneously with production use.

UnixWare supports a number of vital resiliency features, notably Multipath I/ O,and sustains static hardware partitions provided by high-end Intel-based serverssuch as the Unisys ES7000. UnixWare also supports SCOs powerful NonStopClusters, a sophisticated HA package that works with as many as 32 nodes, aCluster File System, and advanced HA functions such as process pairs. However,UnixWare lacks sophisticated resource-management tools, and has only basicFibre Channel capabilities.

ComponentFailure

Resilience9%

Journaling File

System6% HA ClusteringOptions

30%

Operational

Improvements10%

Workload

Management30%

DynamicReconfiguration

15%

FIGURE 7: RAS Criteria and Weightings

FI GURE 7: RAS Criteri a

and Weighti ngs


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COMPONENT FAILURE RESILIENCEServer hardware has become more reliable over time. Server designs increasinglyuse highly integrated components. These components reduce complexity andhence the number of points of failure. Systems also now build in redundant

components, which further improves reliability. For example, areas that are vulnerable to mechanical failure, such as storage, can be protected throughredundancy techniques such as RAID.

Despite these improvements, failures can still occur in critical components thatare expensive and sometimes extraordinarily challenging to replicate at thehardware level, including processors, memory, and I/ O devices. In response,leading-edge UNIX-system developers have introduced resiliency functions thatallow operating systems to adapt to outages by key hardware components insingle systems. In many cases, designers have drawn on techniques that havetraditionally been implemented in mainframes. Emerging operating-system

technology that enables such self-healing includes, DynamicProcessor Resilience allows an operating system to adapt to processor

failure by isolating failed CPU components. In the event of a soft error (anon-fatal error that allows the system to continue processing), the systemgracefully discontinues use of the failed unit. If a processor failure results in asystem crash, the system restarts automatically after isolating the failed unit.

DynamicMemory Resilience allows an operating system to dynamically cordon off memory that has suffered single-bit errors so that software no longer risksusing potentially unreliable areas. Most systems can typically detect andcorrect single-bit failures with Error-Correcting Code (ECC) memory. Withdynamic-memory resilience, however, the operating system registers repeated

single-bit failures in software so that it can isolate affected areas before fataldouble-bit errors occur. Virtual IP Addresses allow IP connections to remain unaffected if physical

network interfaces fail. System administrators define a virtual IP address forthe host, which from a TCP connection standpoint is decoupled from theIP address associated with physical interfaces.

AlternateI/ O Pathing (also known as Multipath I/ O ) allows an operating systemto recover from the failure of I/ O devices such as disk or network adaptersby re-routing I/ O to a backup device, while preserving logical references tothe device so that applications continue processing without interruption.

Tru64 UNIX and HP-UX 11i share the lead in the component-failure-resistancecategory, each deriving a major advantage from its ability to detect and recoverfrom memory errors online. HP-UX 11i continuously checks memory todetermine which type of error has occurred, a Single-Bit hard Error (SBE), or arepeating set of soft errors. If either type has occurred, the four-KB page of memory involved in the failure is deallocated online to prevent a second andfatal 17 bit error. HP-UX 11i also logs these errors for later analysis or reboot so

17 Error-Correcting Code (ECC) memory detects SBEs, but cannot correct them.


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the bad memory is permanently kept offline throughout succeeding boot cycles.Tru64 UNIX includes a Memory Error Troller, which scans memory at aconfigurable rate to flush out SBEs, which are scrubbed/ corrected by PALcodein the AlphaServer hardware. Double-Bit Errors (DBEs) are detected by theTroller, which causes the page to be marked as bad, and hence moved to the

bad page list whenever possible. Note that in both cases, errors could still beencountered as unrecoverable by an application or by the kernel at the time of failures, i.e., prior to deallocation, which potentially results in some applicationfailures.

AIX has the most complete support for handling processor failure. Considerthese typical scenarios. If AIX discovers a processor with too many recoverableerrors during runtime, it will dynamically turn off that processor, while the rest of the system keeps running. 18 If AIX discovers a sick processor or memory block during its boot process, the defective part is turned off and not used. Also, if asystem is halted for a sick processor or memory block, the processor and block are turned off and not used when the system reboots. By contrast, HP-UX,Solaris, and Tru64 UNIX all offer partial support for handling processor failure.HPs memory-error detector works on processor cache memory in addition tomain memory. HP-UX 11i will also trap and check for processor failure whencertain types of page faults occur. If a processor has failed, HP-UX will notify anadministrator who can take the processor down while the rest of the system staysup. Tru64 UNIX can take processors offline automatically if their internal cachegoes bad (using Tru64 UNIXs Memory Error Troller), and allows administratorsto start/ stop processors manually online (including the boot processor). TheOpen Boot PROM (OBP) in Suns servers has a Blacklist feature that preventsconfiguration of components during Power On Self Test (POST). Solaris allowsadministrators to dynamically reconfigure (DR) a board out, blacklist the CPU,and DR the board back in without bringing the server down. This approach givesSolaris the additional advantage of being able to deallocate CPUs even if they arebound to I/ O.

All of the studied systems except UnixWare support Virtual IP Addresses in thebase operating system. HP-UX actually provides three ways to deliver thecapability: LAN Monitor , which protects from the failure of network-adapter cards and

directs IP traffic, which has been routed to failover cards; Auto Port Aggregation (APA) , which provides trunking of multiple network

pipes into a large virtual pipe; and MC/ Serviceguard , HPs HA clustering extension that protects many areas

including network adapters.

HP-UX also supports relocatable IP addresses, which resembles a virtual host IPaddress that can be assigned to an application. Solaris 8s IPMP (IP Multipathing)supports load balancing, auto-failover of connections, and re-establishment of

18 See AIX cpudisable command.


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failed links when repaired. IPMP also reacts to Dynamic Reconfiguration eventsto include newly inserted Network Interface Cards (NICs) while the system isrunning. Tru64 UNIX supports virtual IP addresses as well.

All of the studied systems except AIX support alternate I/O pathing in the base

operating system. HP-UX offers this capability via two functions: PVLinks, whichis used by HPs MC/ ServiceGuard clustering extension, and Auto Port Aggregation (APA), which provides load balancing across adapters. HP-UX alsoincludes native storage failover functions for EMC storage devices when a disk fails, redirection to another disk occurs automatically. Solaris supports AlternatePathing (AP) for most of Suns I/ O devices, with particularly strong DynamicReconfiguration for services such as IP networking. UnixWare supportsMultipath I/ O for certain disk adapters. Tru64 UNIX offers fully dynamic andautomatic Multipath I/ O, including support for EMC storage devices. Tru64UNIXs function includes automatic failover and load balancing, not just forCompaq devices, but for any supported device (including EMC). Tru64 UNIXalso performs load balancing across multiple paths, (where some others only dofailover, and may be limited to two paths only), and also supports multipath tapesand media changers.

DYNAMIC RECONFIGURATION As IT infrastructures become increasingly web-based and globally oriented,servers truly must be able to respond to requests 24 hours a day and 365 days a

year. Operating systems can help to minimize downtime by reducing the numberof administrative tasks that require a system restart, which can consume a greatdeal of time in high-end environments. Dynamic reconfiguration differentiatesoperating systems by allowing online addition and removal of components forrepairs or upgrades with rebooting. Capabilities of this highly prized quality mayinclude, Online CPU and memory reconfiguration allows processors and memory to be

added or removed without rebooting the operating system. Dynamic removalof memory is especially challenging, since it requires the operating system togracefully dry up use of resources that reside in components beingdetached. Online CPU and memory addition is especially useful when coupledwith Capacity-On-Demand programs (see below).

OnlineI/ O reconfiguration allows I/ O devices such as disk adapters and network cardsto be added or removed when coupled with current hardware-reconfiguration

capabilities, i.e., hot-plug Peripheral Component Interconnect (PCI ). Capacity-On-Demand (COD) options allow users to increase the processingpower of systems without disrupting operations. Typically, COD programsinvolve the purchase of fewer processors than are actually installed in thesystem, introducing a distinction between the physical installation and thepurchasers license to use. Extra processors remain idle until more capacity isneeded, at which time users license these processes and the operating systemactivates them. COD options have long been available to users of traditionalhigh-end commercial systems such as mainframes, for which users could


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lease capacity by paying a regular fee. They have now proven particularlyattractive for addressing the wildly fluctuating workloads of web applicationsrelated to e-commerce. Compaq, HP, IBM, and Sun each offer CODprograms for servers running their respective UNIX systems.

Solaris 8 has a major advantage over its competitors in the DynamicReconfiguration (DR) category, fully supporting all studied functions. Solaris 8can arbitrarily add and remove processors online, and is the only studied productthat achieves this. Further, the Automatic Dynamic Reconfiguration (ADR)function in Solaris 8 automates the DR process by simple scripting so thatadministrators do not have to be present when DR is performed. Solaris 8 alsoincludes a toolkit that applications can use to behave correctly given a particularcombination of CPUs and memory. The Reconfiguration Coordination Manager(RCM) provides a standard API for applications to adjust dynamically to availableresources. 19

Compaq has traditionally focused its RAS efforts on HA clusters, rather thansingle-system reliability enhancements. Thus, Compaq seeks to deliver DynamicReconfiguration features by optimizing the Single-System Image (SSI) capabilitiesin TruCluster Server. Compaqs AlphaServers allow online replacement of processors and memory at the hardware level, but Tru64 UNIXs softwaresupport for the capability still lags. 20 Tru64 UNIX allows all processors except the

AlphaServers Master/ Boot CPU to be taken offline and brought back online, butdoes not yet support the addition of new processors. AIX allows administratorsto turn off processors manually. HP-UX allows administrators to take CPUsoffline, and bring them back online. 21 All of the studied systems except Tru64UNIX support dynamic addition and removal of PCI peripherals.

JOURNALING FILE SYSTEM A JournalingFileSystem (JFS) boosts storage reliability by protecting the integrity of the file system. This reduces dramatically the time required to boot a systemconfigured with large amounts of storage after unplanned shutdowns. Journalingemploys transaction-based logging techniques similar to those of databasesystems. Before updating any file system control information (i.e., metadata), theoperating system enters information concerning the update into a disk-based log.Only after the system has confirmed that it has written the user data safely to disk does it attempt to update the actual metadata. If the system loses power orotherwise fails during the metadata update, the JFS can reconstruct the all-

important metadata from information in the log. In this way, file systems always 19 If applications are not properly modified to handle Dynamic Reconfiguration, they will not necessarily be optimized to take

advantage of available resources. For example, dominant applications such as database servers typically make assumptionsabout the number of processors available. If the number changes while the database is running, performance can suffer for a

variety of reasons. Indeed, the Solaris version of Oracle 9i already takes advantage of RCM to deal with this very problem onSuns hardware.

20 Tru64 UNIX will have full CPU hot-swap support in an upcoming release (V5.1A, the same release that will incorporate the ARMTech functionality).

21 HPs vPartitions, due to ship in first quarter 2001, will allow processors to be added/ deleted dynamically.


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move from one consistent state to another, never attempting unsafe writes. All of the studied systems include Journaling File Systems in their base distributions.

Full Journaling is more powerful. It maintains the integrity of the files and the filesystem. Traditional JFS implementations guarantee the consistency of the file

system, but make no effort to protect the consistency of the files themselves. Inthe event of system outage, a file that was being written to at the time of failurecould potentially be in any state when the operating system restarts: fully written,partially written, or wiped out. Full Journaling employs transaction-loggingtechniques to maintain the consistency of the files themselves. This approachboosts uptime by allowing applications to continue accessing critical files that arekept in an expected format.

All of the studied UNIX systems now include Journaling File Systems in theirbase operating-system packages, but HP-UX 11i and Tru64 UNIXs AdvFS filesystem offer Full Journaling. 22 UnixWare pr

2001 Dh Bao s Report

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