Hp Storageworks Xp Auto Path Software

hphphphp StorageWorksauto path users guide

hp-ux

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2002, Hewlett-Packard Company.

E0702 B9510-96003

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2 HP StorageWorks Auto Path: Users Guide (HP-UX)

Contents 3

About this guide 5Revision history 6Technical support 7Warranty statement 8

1 Auto Path features 11ULM services 13Dynamic load balancing 14Automatic failover 15Automatic path recovery 16System requirements 17

2 Installation 19Installing Auto Path software: HP-UX host 20Uninstalling Auto Path: HP-UX host 21

contents


3 Command-line interface 23autopath display 24autopath help 26autopath recover 27autopath retrieve 28autopath set_lbpolicy 29autopath set_prefpath 30

4 Troubleshooting 31Recovering after a failure 32Auto Path messages 33Contacting HP customer service 34

Index 35

About this guide 5

About this guideThe instructions given in this guide are intended for system administrators who already have the following skills and knowledge:

a background in data processing and understanding of direct-access storage device subsystems and their basic functions

familiarity with disk arrays and RAID technology

expertise with the operating system, including commands and utilities

Unless otherwise noted, the term disk array refers to any of these disk arrays:

HP Surestore Disk Array XP48HP StorageWorks Disk Array XP128HP Surestore Disk Array XP256HP Surestore Disk Array XP512HP StorageWorks Disk Array XP1024HP StorageWorks Virtual Array 7100HP StorageWorks Virtual Array 7400

For information about the disk arrays, please refer to the owners manuals.


Revision historyJuly 2001 Preliminary release for HP-UX.

October 2001 First release for HP-UX 11.00 and 11.11.Revised installation instructions.Enhanced the CLI commands.

July 2002 Revised for release 2.00 for HP-UX with ULM services.

Technical support 7

Technical supportTechnical support is provided for this product through an HP Support Contract, purchased at the time you purchased this product. See the HP Support Contract for information about technical support.

For the most current information about this product, visit the support web site:

Auto Path XP www.hp.com/support/apxp

Auto Path VA www.hp.com/support/apva

High-end arrays www.hp.com/support/stressfree

For information about product availability, configuration, and connectivity, consult your HP account representative.


Warranty statementHP warrants that for a period of ninety calendar days from the date of purchase, as evidenced by a copy of the invoice, the media on which the Software is furnished (if any) will be free of defects in materials and workmanship under normal use.

DISCLAIMER. EXCEPT FOR THE FOREGOING AND TO THE EXTENT ALLOWED BY LOCAL LAW, THIS SOFTWARE IS PROVIDED TO YOU AS IS WITHOUT WARRANTIES OF ANY KIND, WHETHER ORAL OR WRITTEN, EXPRESS OR IMPLIED. HP SPECIFICALLY DISCLAIMS ANY IMPLIED WARRANTIES OR CONDITIONS OF MERCHANTABILITY, SATISFACTORY QUALITY, NON-INFRINGEMENT, TITLE, ACCURACY OF INFORMATIONAL CONTENT, AND FITNESS FOR A PARTICULAR PURPOSE. Some jurisdictions do not allow exclusions of implied warranties or conditions, so the above exclusion may not apply to you to the extent prohibited by such local laws. You may have other rights that vary from country to country, state to state, or province to province.

WARNING! YOU EXPRESSLY ACKNOWLEDGE AND AGREE THAT USE OF THE SOFTWARE IS AT YOUR SOLE RISK. HP DOES NOT WARRANT THAT THE FUNCTIONS CONTAINED IN THE SOFTWARE WILL MEET YOUR REQUIREMENTS, OR THAT THE OPERATION OF THE SOFTWARE WILL BE UNINTERRUPTED, VIRUS-FREE OR ERROR-FREE, OR THAT DEFECTS IN THE SOFTWARE WILL BE CORRECTED. THE ENTIRE RISK AS TO THE RESULTS AND PERFORMANCE OF THE SOFTWARE IS ASSUMED BY YOU. HP DOES NOT WARRANT OR MAKE ANY REPRESENTATIONS REGARDING THE USE OR THE RESULTS OF THE USE OF THE SOFTWARE OR RELATED DOCUMENTATION IN TERMS OF THEIR CORRECTNESS, ACCURACY, RELIABILITY, CURRENTNESS, OR OTHERWISE. NO ORAL OR WRITTEN INFORMATION OR ADVICE GIVEN BY HP OR HPS AUTHORIZED REPRESENTATIVES SHALL CREATE A WARRANTY.

Warranty statement 9

LIMITATION OF LIABILITY. EXCEPT TO THE EXTENT PROHIBITED BY LOCAL LAW, IN NO EVENT INCLUDING NEGLIGENCE WILL HP OR ITS SUBSIDIARIES, AFFILIATES, DIRECTORS, OFFICERS, EMPLOYEES, AGENTS OR SUPPLIERS BE LIABLE FOR DIRECT, INDIRECT, SPECIAL, INCIDENTAL, CONSEQUENTIAL, PUNITIVE OR OTHER DAMAGES (INCLUDING LOST PROFIT, LOST DATA, OR DOWNTIME COSTS), ARISING OUT OF THE USE, INABILITY TO USE, OR THE RESULTS OF USE OF THE SOFTWARE, WHETHER BASED IN WARRANTY, CONTRACT, TORT OR OTHER LEGAL THEORY, AND WHETHER OR NOT ADVISED OF THE POSSIBILITY OF SUCH DAMAGES. Your use of the Software is entirely at your own risk. Should the Software prove defective, you assume the entire cost of all service, repair or correction. Some jurisdictions do not allow the exclusion or limitation of liability for incidental or consequential damages, so the above limitation may not apply to you to the extent prohibited by such local laws.

NOTE. EXCEPT TO THE EXTENT ALLOWED BY LOCAL LAW, THESE WARRANTY TERMS DO NOT EXCLUDE, RESTRICT OR MODIFY, AND ARE IN ADDITION TO, THE MANDATORY STATUTORY RIGHTS APPLICABLE TO THE LICENSE OF THE SOFTWARE TO YOU; PROVIDED, HOWEVER, THAT THE CONVENTION ON CONTRACTS FOR THE INTERNATIONAL SALE OF GOODS IS SPECIFICALLY DISCLAIMED AND SHALL NOT GOVERN OR APPLY TO THE SOFTWARE PROVIDED IN CONNECTION WITH THIS WARRANTY STATEMENT.

Auto Path features 11

1

Auto Path features

HP Auto Path provides automatic input/output (I/O) path failover, failback, recovery, and load balancing for host systems configured with multiple host adapters and connections to a disk array.

Auto Path provides enhanced data availability with these features:

automatic path failover to an alternate path

automatic path recovery after failed path is serviced

automatic failback when a path recovers from failure

dynamic load-balancing over multiple paths

command-line user interface (CLI) for Auto Path management

ability to reestablish previous load-balancing policy after reboot through the CLI

The HP Auto Path software performs dynamic load balancing of data flow through multiple paths. It detects multiple paths to each logical device and distributes the data load among the paths for optimum performance.

The user interface lets a system administrator define load balancing policies and preferred paths, and view device path information. Auto Path manages


paths according to the balancing policy, ensuring that no single path is a performance bottleneck.


ULM servicesThe SCSI Upper Layer Module (ULM) interface is used by Auto Path and similar modules to provide flexible configuration and layering of modules above the SCSI disk drivers. In order for Auto Path to be configured into 11.0/11.11 (and coexist with other pseudodrivers) Auto Path must register itself with the ULM services for each LUN path that it wants to control.


Dynamic load balancingAuto Path performs dynamic load balancing while monitoring each path to ensure that the I/O transaction is completed. The load balancing policy is selected by the administrator.

The dynamic load balancing policy prevents any path from becoming overloaded, and it helps to prevent the congestion that occurs when many I/O operations are directed to common devices along the same path.

If a preferred path is used for a device, the entire I/O for that particular device flows through the preferred path and no load balancing is done by Auto Path for that device.

VA disk arrays

Increased performance is not always realized with Virtual Array systems. In most cases, the best performance is provided by using preferred paths.


Automatic failoverIn the event of a failure of any part of a path between the disk array and a server, Auto Path automatically switches to an alternate path, dropping the failed path out of the I/O rotation without any loss of data. The failover is not visible to applications, so normal operation continues without downtime.

For troubleshooting information, see Troubleshooting (page 31).


Automatic path recoveryWhen a path fails, it is no longer used. After the path is returned to normal, Auto Path automatically begins using the path with the designated load balancing policy. No user action is necessary.

If the failed path was set as the preferred path, after the path is recovered, Auto Path automatically begins using the preferred path. No user action is necessary.


System requirementsTo install Auto Path, the system must conform to these requirements:

HP-UX 11.00 or 11.11 64-bit operating system

administrator root access to the host system

SCSI Upper Layer Module Services installed on the system

HP-UX 11.00: version B.11.00.01

HP-UX 11.11: version B.11.11.01

For specific installation requirements for your system, contact your HP account representative.

Additional information Be sure to view the readme.txt on the Auto Path installation CD-ROM for important information about product limitations.

Installation 19

2

Installation

This chapter describes the procedures for installing Auto Path. Installation of Auto Path software is performed by users with administrator privileges.

The HP account representative can assist in determining the supported configurations for your system.


Installing Auto Path software: HP-UX hostBefore installing Auto Path software, ensure that SCSI Upper Layer Module Services is installed on the system.

To install Auto Path, you must have superuser (root) access on the HP-UX host.

Caution Read the readme.txt file on the installation media for more details about installation.

To install Auto Path:

1. Log on to the HP-UX system as superuser (root).

2. Insert the Auto Path installation CD into the CD-ROM drive.

3. Mount the CD on your file system.

4. Assuming that the CD was mounted to a directory called /cdrom, from the command line, execute the swinstall command:

For installation on HP UX 11.00, execute: swinstall s /cdrom/autopath_HPUX_11.00.depot

For installation on HP UX 11.11, execute:swinstall s /cdrom/autopath_HPUX_11.11.depot

Follow the instructions for swinstall.

Installation of the Auto Path package creates the /Autopath directory under /opt and copies the readme.txt, autopath.pdf, and changes.log files to this directory.

Installation 21

Uninstalling Auto Path: HP-UX hostTo uninstall Auto Path:

1. Log on to the HP-UX system as superuser (root).

2. From the command line, execute the swremove command.

Select the Auto Path product for removal.

The system reboots after removal is completed.

Command-line interface 23

3

Command-line interface

The Auto Path command-line interface (CLI) can be used only on hosts connected to devices with the Auto Path driver installed. The commands supported by this interface and the syntax are described here:

autopath display (page 24)

autopath help (page 26)

autopath recover (page 27)

autopath retrieve (page 28)

autopath set_lbpolicy (page 29)

autopath set_prefpath (page 30)


autopath display Display devices

Syntax autopath display { path | all }

path Specifies the physical device path.

all Details about all Auto Path devices in the system.

Description The autopath display command displays details about Auto Path devices such as alternate paths to an Auto path device, associated status, Load Balancing policy settings.

In the output, (PP) indicates the preferred path.

Examples # autopath display /dev/dsk/c3t0d1Auto Path Driver Version: VER 2.00.00Auto Path CLI Version : VER 2.00.00

Details for path: /dev/dsk/c3t0d1

Load Balance Policy : Round Robin

=========================================================

Device Paths Device Status=========================================================

/dev/dsk/c3t0d1 Active /dev/dsk/c5t0d1 Failed=========================================================


HP $ autopath display all

Auto Path Driver Version: VER 2.00.00Auto Path CLI Version : VER 2.00.00


Load Balance Policy : Preferred Path

=========================================================


/dev/dsk/c3t0d0(PP) Active /dev/dsk/c5t0d0 Active=========================================================


Load Balance Policy : Round Robin

=========================================================


/dev/dsk/c3t0d1 Active /dev/dsk/c5t0d1 Failed=========================================================


autopath help Display help

Syntax autopath help

Description The autopath help command displays a list of Auto Path commands and their syntax.

Example HP $ autopath helpautopath: Usage: autopath display [all|pathname] autopath help autopath recover autopath retrieve autopath set_lbpolicy policy pathname autopath set_prefpath pathname


autopath recoverRecover failed paths

Syntax autopath recover

Description The autopath recover command spawns a process to enable automatic path recovery. This command can be automatically activated during system bootup.

If the process is terminated or is not invoked automatically, you can invoke this command from the command line to enable the automatic path recovery feature.

Relatedinformation

Automatic path recovery (page 16)


autopath retrieveRestore Auto Path settings

Syntax autopath retrieve

Description The autopath retrieve command restores the load balancing policy and preferred path settings across system reboots.

Retrieval of settings may not be effective if SAN configuration changes have been made for the host.


autopath set_lbpolicySet load-balancing policy

Syntax autopath set_lbpolicy policy path

policy The load balance policy name:

NLB no load balance policyRR round robinSQL shortest queue lengthSST shortest service time

path The physical device path.

Description The autopath set_lbpolicy command sets the load balance policy for the specified device path.

Example HP $ autopath set_lbpolicy RR /dev/dsk/c0t0d0autopath: Load Balance Policy set successfully for /dev/dsk/c0t0d0


autopath set_prefpathSet preferred path

Syntax autopath set_prefpath path

path Specifies the physical device path.

Description The autopath set_prefpath command sets the preferred device path to an Auto Path device. When the path details are displayed with the autopath display command, the preferred path is marked (PP).

Example HP $ autopath set_prefpath /dev/dsk/c4t0d0autopath: Preferred path set successfully for /dev/dsk/c0t0d0

Troubleshooting 31

4

Troubleshooting

Troubleshooting can be performed by the customer or an HP service representative in accordance with your HP service contract. If you are unable to resolve an error condition, ask your HP service representative for assistance.


Recovering after a failureWhen a path fails, it is no longer used by Auto Path. After the path is returned to normal, Auto Path automatically begins using the path with the designated load balancing policy. No user action is necessary.

If the failed path was the designated preferred path, after the path recovers, Auto Path automatically begins using the path as the preferred path. No user action is necessary.

Tip If a path to the device has been serviced and the device failover does not occur, check whether the autopath recover command has been terminated inadvertently. If so, restart the recovery process by executing the autopath recover command.

Related information autopath recover (page 27)

Troubleshooting 33

Auto Path messagesAuto Path reports errors, diagnostic messages, and informational messages to the /var/adm/syslog/syslog.log file. The user can execute dmesg command to view the messages reported by Auto Path. Auto Path reports the following messages:

Event Sample message

DEVICE ACCESS FAILURE AUTOPATH: Warning: Unable to access device 0x1f040000

MAXIMUM LUN COUNT LIMIT AUTOPATH: Warning: LUN count reached maximum value of 65536. Last device recognized is 0x1f040000

MAXIMUM PATH COUNT REACHED MESSAGE

AUTOPATH: Warning: Cannot add path 0x1f040000 as an alternate link. Path count to end device reached maximum value of 8

ULM REGISTRATION FAILURE AUTOPATH: Warning: Cannot register path 0x1f040000 as an Auto Path device. Path is already registered

PATH FAILED MESSAGE AUTOPATH: Path 0x1f040000 failed! Rerouting IO to alternate path

ALL PATHS FAILED MESSAGE AUTOPATH: All the paths to the end device 0x1f040000 failed!

PATH RECOVERED MESSAGE AUTOPATH: Path 0x1f040000 recovered

MEMORY ALLOCATION FAILURE

AUTOPATH: Warning: Memory Allocation failed


Contacting HP customer serviceIf you call HP customer support, provide as much information about the problem as possible, including the circumstances surrounding the error or failure and the exact content of any error messages displayed on the host system.

Index 35

AAuto Path

features 11autopath display

syntax description 24autopath help

syntax description 26autopath recover

syntax description 27autopath retrieve

syntax description 28autopath set_lbpolicy

syntax description 29autopath set_prefpath

syntax description 30

Ccommand-line interface

syntax descriptions 23

Ddeinstallation

Auto Path 21disk arrays

supported 5

Ffailover

automatic 15

HHBA

supported driver pairs 17HP customer service

contacting 34

index


Iinstallation

Auto Path 19deinstalling 21HP-UX host 20requirements 17

Lload balancing

description 14

Ppath

automatic recovery 16

Rrecovery

actions needed 32

SSCSI Upper Layer Module (ULM)

services registration 13

Ttips

device failover 32troubleshooting

Auto Path 31

UULM

registering Auto Path 13

hp StorageWorks auto pathusers guideContentsAbout this guideRevision historyTechnical supportWarranty statementAuto Path featuresULM servicesDynamic load balancingAutomatic failoverAutomatic path recoverySystem requirements

InstallationInstalling Auto Path software: HP-UX hostUninstalling Auto Path: HP-UX host

Command-line interfaceautopath displayautopath helpautopath recoverautopath retrieveautopath set_lbpolicyautopath set_prefpath

TroubleshootingRecovering after a failureAuto Path messagesContacting HP customer service

Index

Hp Storageworks Xp Auto Path Software

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