h11631 Using Unisphere Vmax Manage Symmetrix Ckd Devices Os Environment Wp

8/10/2019 h11631 Using Unisphere Vmax Manage Symmetrix Ckd Devices Os Environment Wp

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White Paper

USING UNISPHERE FOR VMAX TO MANAGESYMMETRIX CKD DEVICES IN A z/OS

ENVIRONMENT

Abstract

This white paper provides an introduction to the capabilities ofUnisphere for VMAX for administering z/OS Mainframe-attacheddevices. Delivering z/OS-specific configuration managementmakes Unisphere a powerful tool for Symmetrix VMAX users inthe z/OS Mainframe environment.

June 2013


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2Using Unisphere for VMAX to Manage Symmetrix CKD Devices in a z/OS Environment

Copyright 2013 EMC Corporation. All Rights Reserved.

EMC believes the information in this publication is accurate asof its publication date. The information is subject to changewithout notice.

The information in this publication is provided as is. EMCCorporation makes no representations or warranties of any kindwith respect to the information in this publication, andspecifically disclaims implied warranties of merchantability orfitness for a particular purpose.

Use, copying, and distribution of any EMC software described inthis publication requires an applicable software license.

For the most up-to-date listing of EMC product names, see EMC

Corporation Trademarks on EMC.com.

Part Number h11631


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Table of Contents

Executive summary............. ............. ............ ............. ............. ............ .......4

Audience .................................................................................................................... 4

Overview................................................................................................5

Symmetrix configuration .............................................................................................. 5

Unisphere for VMAX and Solutions Enabler .................................................................... 6

Unisphere for Count Key Data devices .. .... .... .... ..... .... ..... .... ..... .... ..... .... ..... .... 7

Array properties........................................................................................................... 7

Free space .................................................................................................................. 8

Device creation: CKD 3390 devices ............................................................................... 9

Device duplication ................................................................................................. 10

SSID management ................................................................................................. 11

Mapping CKD devices ................................................................................................ 12

Device mapping .................................................................................................... 14

Mapping devices ................................................................................................... 14

Unmapping CKD devices ............................................................................................ 15

Assigning aliases....................................................................................................... 16

Unassigning aliases................................................................................................... 17

Device online/offline considerations ........................................................................... 18

CKD assignment change: EMC restrictions ................................................................... 18

CKD assignment change: z/OS restrictions .................................................................. 19

Conclusion................................................................................................................ 19

References ........ ............. ............ ............. ............. ............ ............. ....... 19

Appendix ............ .............. ........... ............. .............. ............. .............. .. 21

Z series hardware complex ......................................................................................... 21

Example of HCD configuration parameters ................................................................... 22

Parallel Access Volumes............................................................................................. 22

Planning addresses for static PAV ........................................................................... 24

Planning addresses for dynamic PAV ....................................................................... 26


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Executive summary

As EMCstorage-management tools have evolved to meet the intricate and wide-ranging needs of many different enterprises, the capabilities of these tools haveincreased, alongside their complexity. One outcome of the advancement in storage-management functionality is a large and varied set of options available in each tool,making EMC storage-management products very powerful but daunting toinexperienced users.

In response to customer concerns for ease of use, EMC introduced UnisphereforVMAX, which employs a simple and intuitive Web-based user interface to administerthe most common daily storage-management functions for a Symmetrixarray. Thebenefit is that Unisphere can be used quickly and efficiently by operators of allexperience levels.

When using Unisphere, Mainframe storage administrators can avoid consultationwith EMC personnel on array change-control activities and perform the actionsthemselves, thus removing one level of complexity in the change-control process.This allows for changes to be enacted in a more timely fashion, and it also avoidscommunication errors when Unisphere is used by authorized customer administratorswho directly perform array modifications.

Unisphere puts control of the following Symmetrix array activities into the hands ofthe Mainframe storage administrator:

Device creation and removal

Device base and alias addressing

Local and remote replication

Quality of service

Unisphere is intended to make array management faster and easier. Using dialogboxes structured into configuration wizards, Unisphere accelerates setup,configuration, and routine tasks. By providing simplified replication management andmonitoring, Unisphere delivers ease of use that translates into efficient operation.Finally, managing for the future, Unisphere will make new functionality available inthe same simple intuitive manner, greatly lessening the learning curve necessary toimplement any new technology. With Unisphere, the Mainframe user community nowhas a new choice in Symmetrix array management.

Audience

This white paper is intended for any reader interested in understanding the potentialof Unisphere for simplified management of Symmetrix array-configuration tasks forthe mainframe. It will be of particular interest to storage administrators, systemprogrammers, or any technology professional concerned with managing Count KeyData devices on a Symmetrix storage platform. This paper assumes that the reader isfamiliar with storage array-configuration requirements in a mainframe environment.


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Overview

Unisphere delivers a Web-based graphical user interface that allows point-and-clickselection of objects and action sequences. User-selected objects and actions arepassed to the SYMAPI, enabling array management with the ease and intuitiveapproach of point-and-click.

A z/OS Mainframe-attached Symmetrix must obey configuration characteristicsdefined by the host operating system. Running Solutions Enabler on the z/OS hostprovides some additional information not available to Solutions Enabler running onthe Unisphere server. These topics are explored in the following sections as aprerequisite to the later examination of Unisphere mainframe-management activities.

Symmetrix configuration

When a Symmetrix array is connected to a mainframe, either ESCON (EA) or FICON (EF)directors are present in the array. Based on the evolution of mainframe hardwarecomponents, several key configuration structures are associated with the devicesaddressed on the EA or EF directors.

In original mainframe implementations, a Control Unit (CU) managed commands fromthe Channel Subsystem to a particular disk drive. Although early CUs had less than256 drives assigned to them, this number of 256 represents today's maximumdevices that can be defined within a CU. As storage arrays advanced to contain morethan 256 volumes/devices, arrays presented Logical Control Units (LCUs) to theChannel Subsystem, outgrowing the physical limits of previous hardware. Each CU,and indeed each LCU, had its own unique Subsystem ID (SSID), and the legacy ofthese structures remains in place today. Addressing on EA and EF directors is dividedinto (Logical) Control Unit images that each have their own unique SSID and contain amaximum of 256 devices.

Although the Symmetrix Storage array with EFs can emulate up to 255 (Logical)Control Units per director port, another logical abstraction became necessary in somecustomer environments. The new requirement was for the Symmetrix array to logicallyrepresent several arrays. Within the EMC configuration program (SymmWin), eachlogical array is referred to as a split. With splits defined, the Symmetrix array couldcontain the same LCU addresses several times (duplicates), but the SSIDs for eachLCU would be unique. Each instance of the duplicate LCU address scheme is in adifferent split, and each split appears as a separate array by slightly modifying theoriginal array serial number. Currently, manipulation of split definitions is onlyavailable to EMC Customer Service Representatives, but LCU addressing and SSIDdefinition is achievable using Unisphere.

Within the LCU context, there are operating system restrictions surrounding thedevices. Disk hardware evolution is responsible for requirements built into theSymmetrix configuration program. Disk-drive track formatting and disk-drive size hasbeen standardized by the mainframe disk products of the past. Although variation insize is possible, normal configuration practices are to use the standard drive sizessuch as 3390-1, 3390-3, 3390-9, 3390-2,7 and 3390-54. Unisphere has these


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definitions built into Configuration Wizards to make device creation as simple aspossible. When Parallel Access Volumes (PAVs) are present, only one type ofgeometry can exist in each CU image. Also, 3380 track geometry is available withSymmetrix arrays. EMC can mix 3380 disk geometry with 3390 geometry on a physicaldrive. Further, when the (PAV) feature is not present, 3380 and 3390 devices canexist in the same CU, although the need for this type of configuration has almost been

eliminated.The process to build and load a configuration change by means of Unisphere parallelsthe process used by EMC service staff. Symmetrix configurations are held in a binarydata structure commonly called the bin file. This configuration file is managed fromthe Symmetrix Service Processor (SP) by way of the SymmWin application.Configuration change parameters are collected by means of the point-and-clickinterface of Unisphere and sent to the SYMAPI server. The SYMAPI server generatesSystem Calls (Syscalls) to pass the configuration parameters to the Symmetrix arraywhere SymmWin builds a new bin file, combining the current configuration with theUnisphere configuration change parameters. Validity checks are performed againstthe new bin file, and if the intended configuration upgrade is legal, a script is initiated

to load the new configuration.

Unisphere for VMAX and Solutions Enabler

Unisphere is installed on a Windows, UNIX, or Linux Server where it runs as a serviceor a process. A Unisphere user (client) communicates with the Unisphere Service bymeans of a web browser, such as Internet Explorer, Chrome, or Firefox. The Unisphereservice/process allows the client to select array objects and action options with apoint-and-click interface. The Unisphere service/process then passes the collectedparameters to the Solutions Enabler SYMAPI, which accomplishes the low-levelcompletion of the array-management task.


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Figure 1. Unisphere for VMAX with remote SYMAPI installation

Unisphere can be installed with the SYMAPI running on the same server as SolutionsEnabler (SE). This is a local installation. Unisphere can also be installed with theSYMAPI running on a different server as Solutions Enabler. This is a remoteinstallation. For Unisphere management of Count Key Data (CKD) devices in a z/OSenvironment, there is a benefit to installing Unisphere with Solutions Enabler runningremotely on the z/OS host. This remote installation is shown in Figure 1.In thisdiagram, the SYMAPI has access to z/OS information about online Symmetrixdevices. This z/OS information includes VOLSER and device-number details obtainedfrom the z/OS operating system. InFigure 2,the Unisphere display of CKD RegularVolumes shows the Unit Control Block (UCB) address and VOLSER information. If theVOLSER and the UCB address are required for management of Symmetrix devices,then Unisphere must be installed with Solutions Enabler running under z/OS.

Figure 2. Remote SYMAPI installation can obtain VOLSER and device number

Unisphere examples used within this document are based on the following minimumversions of software: Unisphere for VMAX V1.5.1, EMC Solutions Enabler V7.5, andEnginuity version 5876 Q2 2013 SR.

Unisphere online help provides additional details on the full range of UnisphereSymmetrix resource-management functionality.

It is advisable to invoke the appropriate z/OS DISPLAY, DEVSERV, VARY device andPATHING related system commands to validate Unisphere Symmetrix configuration

changes. Refer to the appropriate IBM z/OS reference documentation, z/OSSystemCommands, for detailed system-command syntax.

Unisphere for Count Key Data devices

Array properties

Symmetrix array management begins by understanding the elements available forcontrol and the action items that can be performed with these elements. Figure 3captures the CU Images view from a Unisphere instance. For CKD devices, the CU

images are immediately visible in the object tree under the Symmetrix unit. Thisallows for easy interrogation of CU devices and properties. On the right-most side,Common Tasks are displayed. They are capable of opening additional ConfigurationWizards.

As expected with a point-and-click interface, further properties information isavailable by selecting additional fields. Select SSID 0x01, and the next display will


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show Properties for that SSID. Once that display is visible, selectVolumes240

for alist (abbreviated in this example) of volumes assigned to that CU Image.

Figure 3. Unisphere array properties

Free space

Understanding free space on a Symmetrix system is an important aspect of arraymanagement. In System Dashboard, a feature of Unisphere, physical and virtualcapacity, both free and used, are reported. An easy-to-read graphic is displayed,giving a very obvious used-to-free capacity comparison (see Figure 4 on the followingpage). Although fixed-block architecture and CKD architecture can exist on the samephysical drive, the free-capacity report presents information in one format only, andthat is in terms of drive native blocking, 512 bytes per block. Emulation of the CKD

format consumes slightly more space than native blocking on the disk.

Free-space information is relevant when creating additional devices and also may beuseful when confirming performance configurations where drives are deliberately leftunderutilized. Be aware that as maximum disk capacity is approached, the total freespace may become more difficult to fill. Although free space can be reported, device-creation requests may not find sufficient contiguous space on appropriate drives for


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the desired protection strategy. Unbalanced utilization of drives may leave someprotection partners (RAID groups or mirror groups) with uneven free space and theinability to complete a device-creation request.

Figure 4. Unisphere: Free space

Device creation: CKD 3390 devices

Figure 5 shows the Storage Volumes dashboard. From here, select Create Volumesunder the Common Tasks heading to open the Configuration Wizard.

Figure 5. Unisphere : Free Space

Figure 6 illustrates the Unisphere selection choices necessary to create new devices.The array object has already been selected and identified by serial number on theUnisphere home page.

From this point, navigate to the Storage display, and select Volumes . Then selectCreate Volumesunder Common Tasks. This opens the Create Volumes ConfigurationWizard. In this example, a CKD-3390 10017 cylinder volume is requested. The new


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volume will be created as a 2-Way Mirror with 7.93 GB capacity from space on anyavailable disk.

The Select SSID tab, when activated, indicates the current number of SSIDs in use,mapped and unmapped devices, device numbers currently present, and maximumdevices allowed (256). This example uses SSID 0001 as a temporary SSID for thenewly created, but currently unmapped, device.

When the device mapping option is used to map the newly created device to theappropriate EF/EA directors, the final SSID will be specified. Refer to the SSIDmanagement section on page 11 for more information on why a temporary SSID isused between device creation and device mapping. Also, note that the device-creation dialog box has selectable tabs to create other volume types, Virtual, Privateor Template. This example shows the Regular device creation template, but all fourtemplates are available in the dialog box to create the various device types.

The dialog box presents options to either create the volume immediately or Add to JobList so it can be created at a later time or date.

Figure 6. CKD 3390 device creation

Device duplication

The example of device creation uses a Configuration Wizard to prompt for correctparameter input. But once those parameters have been supplied, it is necessary tosupply them again for future creation tasks. If there are volume standards, an existingdevice can be a model for the duplication of that type of volume. By using theprinciple of duplication, the creation process is simplified even more.Figure 7outlines the duplication option.

Select Storage> Volumesto open the Volume Dashboard. In the Volume Type panel,select the type of volume, and then select Viewto open the Volumes lists. Select the


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volume, and select>

(>>

which translates toMore

) to open the Duplicate Volumedialog box.

The number of new devices is an essential parameter that must still be supplied.Another necessary input is the temporary SSID that will be used until the new devicesare assigned to EF/EA directors. There is an Override option that can be used tomodify any parameter in the template, however, it must be used every time to specify

the temporary SSID. Refer to the SSID management section for more information onwhy a temporary SSID is used between device creation and device mapping.

Because Unisphere intelligently activates options applicable to selected objects andtasks, the Device duplication template will not be available for SRDF devices. Thesedevices require the specification of remote parameters. The template does notaccommodate entries for remote parameters. If SRDF devices are used as the modeldevice, the Duplicate Device option will be unavailable.

Figure 7. CKD 3390 device duplication

SSID management

z/OS has rules for subsystem IDs (SSIDs) that are enforced by Unisphere when

creating a Symmetrix configuration for CKD devices. By enforcing the operatingsystem rules, Unisphere prevents illegal configurations being loaded onto theSymmetrix system. One such z/OS rule policed by Unisphere is that all devices withthe same SSID must be assigned to the same set of channels (EA/EF director set).

Because device-creation and device-mapping operations are performed in twoseparate configuration load operations, there is always a period of time when devices


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exist but are not mapped. Consequently, a temporary SSID must be chosen at devicecreation and remain in place until the mapping task is completed for operations thatare not exactly a CU image (256 or a multiple of 256 devices). Each of the threepreceding discussions of device creation includes this mandated use of a temporarySSID at device creation until the new devices are assigned to EA/EF directors.

The other essential SSID rule specifies that there must be only one SSID within a CU

image (of 256 devices.) Care must be taken when selecting the final SSID. There isonly one correct value if addresses already exist to define a CU image, and that is theexisting SSID for that CU.

Mapping CKD devices

To access a device from a mainframe host, the device must be mapped to one ormore front-end EA or EF director ports. The Hardware Configuration Definition (HCD)should be configured to reflect the Symmetrix devices, and the associated InputOutput Definition File (IODF) must be loaded and active.

Front-end port mapping is the Symmetrix mechanism for exporting the logical view of

devices to the z/OS system. Devices are usually offline to z/OS until a Volume Tableof Contents (VTOC) is in place and a Vary Online command marks the device as ready.Completion of these steps allows the mainframe host to recognize devices as readyfor read and write operations. Unmapped devices have been created but have eithernever been mapped or were mapped and later explicitly unmapped. As shown inFigure 8, a group of devices becomes part of a CU image when mapped to front-endEA or EF ports. UCBs manage device addresses within the z/OS operating system. TheLPAR (Logical Partition) is a subset of processing resources within a complex thatforms the environment containing the running operating system.

Figure 8. CU images and mapped devices

A z/OS mainframe can access multiple CU images. A CU image contains up to 256device addresses (numbered 0x000 through 0x0FF). A device can be in only one CUimage. Each CU image has a unique Subsystem ID (SSID). By contrast, the Symmetrixsystem can have many CU images, the total of which is dependent on model andEnginuity code level.


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When PAVs are enabled, the base and alias addresses for a device must be the sameacross all ports of an EA processor. (An EF does not have multiple ports.) Although itis common for EA port A(0) and port B(1) to be mapped exactly the same, some olderconfigurations addressed port A(0) to one range of devices and port B(1) to a differentrange of devices. Once PAV is enabled, these mixed configurations are no longervalid.

Commencing with Enginuity 5771, an enhanced splitconfiguration managementstructure was incorporated into the Symmetrix configuration program. The new splitstructure reduced the time required to correlate and manage split path groups.Unisphere detects the running Enginuity version for each array and intelligentlyenables the appropriate command templates. Examples of both command templatesare shown in the following pages.

A Symmetrix split can contain multiple LCU images. The CU images are bound toselected EA/EF director ports defining the split. Currently, 16 splits can be configuredin a Symmetrix system running Enginuity 5771 and higher.

It is possible to map duplicate CU image numbers to different splits. Duplicate

(Logical) Control Unit images are assigned to different Symmetrix devices and havedifferent SSIDs. The array serial number presented by each split is slightly modified toallow the associated hosts LPAR to interpret the duplicate CU image number as a(Logical) Control Unit within a unique array. In this manner, IOCP conformity can bemaintained when replacing a number of existing smaller Symmetrix units andcollapsing the existing configurations into the single larger Symmetrix system.

Figure 9 shows the Unisphere CU Image display for the Symmetrix array, serialnumber 4575. The list of CU Images shows duplicate CU numbers. In this case, thereare two instances of CU 00. The presence of two instances of the same CU imageindicates that two splits are active. Notice however that even though the CU numbers

are duplicated, the SSID is unique. Whether the CU image is online or offline all SSIDswithin a complex must be unique.

Figure 9. Duplicate CU image numbers indicating splits


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Device mapping

Because Enginuity includes the split management screen (see Mapping CKDdevices on page 12), mapping for EA/EF directors in a group is accomplishedautomatically by the SymmWin application. Choosing one EA/EF port in a groupmeans all ports in that group receive the same mapping. However, the previouslydiscussed situation for port addressing when PAVs are enabled is still in effect. The

base and alias addresses for a device must be the same across all ports of an EAprocessor. (Again, an EF does not have multiple ports.) Although both ports musthave the same addresses, they should not map to the same LPAR. The A(0) and B(1)ports share the one logical processor (multiplexed). If ports in this mode areconfigured to the same LPAR, excessive CU Busy and CU End conditions andcontention could exist during z/OS Channel Path rotation selection. The possibility ofcontention is alleviated when addresses for the A(0) and B(1) ports are attached todifferent LPARs.

Remember, the first base address assigned to a CU image must be a multiple of0x010. When planning to add base addresses using Unisphere functionality, it is

important that this MVS restriction be observed. If base address 00 is in place,satisfying the MVS rule, then all other address modifications are legitimate.

Mapping devices

When performing a mapping operation, the devices exist but are not yet in a CU.Select Storage> Volumesto open the Volume Dashboard under the appropriate array,which is identified by serial number. In the Volume Type panel, select CKD. UnderGeneral Volumes, select

Regular

,Virtual

,Meta

orPrivate

. Next, select the Volumetype (in this example, Private/2-Way Mir). Select

View

to open the Volumes lists. If thelist of correct devices for mapping is known, any device can be selected and themapping template started and completed using the known device numbers. Choose

the volumes, and click z/OS Mapto open the z/OS Map dialog box.The z/OS Map Volume dialog box requires the following entries, as detailed in Figure10:

The device range to be mapped.

The base address, including the identifying CU number.

The starting alias address, if aliases are to be used. (For information on aliases,see Assigning Aliases on page 16.)

The correct SSID for this CU. (The SSID number will be unique within the Complex.It corresponds to one of the ports that currently is grouped in the split and has thesame addressing.)


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Figure 10. Mapping devices

Unmapping CKD devices

A range of CKD devices with base addresses can be unmapped from the associatedEA or EF ports. If the devices being unmapped have alias addresses allocated in the

configuration, all the aliases in the CU image are also removed. Aliases are specifiedas a range, and holes in the alias range caused by device removal is prevented. Whenaliases are removed, the whole range is removed and added back in a contiguousblock.

Once alias considerations have been resolved, the unmapping process can becompleted. An item worthy of note is that the first base address assigned to a CUimage must be a multiple of 0x010. When planning to remove base addresses, it isimportant that this z/OS restriction be observed. If base address 00 remains in place,satisfying the z/OS rule, then all other address modifications are legitimate. Whenunmapping z/OS devices, associated paths should be varied offline to the devices.Ensure that volumes/datasets are deallocated to z/OS resources prior to anyunmapping activities.

Note:When all devices are unmapped from an ESCON or FICON director, that directorwill go into a DD state. Symmetrix configuration scripts knowwhen to expect thisstate, and steps are in place to accommodate the presence of DD directors, but thescript is lengthened when bringing DD directors back to full functionality.


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When performing an unmapping operation, selectHosts> CU Images

to open the CUImages view. (In this example, specific volumes are chosen to be unmapped.) The CUImage object contains the existing mapped devices, therefore, the CU Image is theappropriate starting control object. Select the correct CU object available under thecorrect array, which is identified by serial number. Select the CU Image and the SSIDthat contain the volumes that are to be unmapped. Select the volumes, and click

z/OS Unmap. This opens a Configuration Wizard dialog box.The z/OS Unmap Volumes dialog box requires the following entries, as detailed inFigure 11:

The device range to be unmapped.

The SSID that will be used while the devices are unmapped. (See SSIDmanagement on page 11.)

One of the ports that currently is grouped in the split and has the sameaddressing. The unmapped devices will be unmapped from all the grouped portssimultaneously by the split management in SymmWin.

Figure 11. Unmapping devices

See Mapping CKD devices on page 12 for an explanation of the split concept.

Assigning aliases

In the event that improved I/O device performance is required, Unisphere provides forthe assignment of alias ranges to base devices. (Refer to IBM WLM DASDcharacterization benchmarking analysis). On a Symmetrix array running Enginuity


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56XX or earlier, you have to assign PAV alias addresses. However, with Enginuity5771 and higher, you can now assign a range of PAV aliases to mapped CKD volumes.

Select Hosts> CU Imagesto open the CU Images view.Figure 12shows the Unispheredialog-box choices to assign an alias range. Select CU Image 0x00, and click > (More)to open the Assign Alias Range dialog box. Enter the values for the starting andending alias addresses, and execute the dialog box.

Figure 12. Assigning alias range

Unassigning aliases

Unisphere provides for the removal of alias ranges from base devices in the eventthat additional channel addresses are required for allocation to Symmetrix devices(returning base addresses to the CU).Figure 13 shows the Unisphere dialog-boxchoices to unassign alias range F0 through FF on CU number 00.


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Figure 13. Remove alias range

Device online/offline considerations

The CKD assignment-change rules and device online/offline considerations aresummarized here. The information is from Primus Solution EMC77918.

1.

A device must only be in one CU.

All addresses for a given device must be the same on all ports to which thatdevice is mapped. In the past, it was possible to address a device as 00 on someports and 100 on other ports. This was still base address 00, however, it reflecteda different CU image on different ports. Such addressing is no longer legal.

2.

Empty ports are not allowed.

If a configuration change involves temporarily removing all devices from adirector, then the task will be treated as removal and re-addition of the director.The director will drop DD and be reloaded with a single director IML.

3.

Devices shared with FBA can have aliases (InfoMover and FDR/SOS).

4.

Two different splits in a Symmetix unit cannot intersect.

A split uses a serial-number modifier to generate a slightly different serial numberto the host. Each split in a Symmetrix array presents a unique CU serial number to

the mainframe host, and there are a maximum of 16 splits allowed in a Symmetrixframe. Obviously, you cannot have overlapping serial numbers. Illegal bins withserial-number modifier errors cannot be created with the CKD assignmentcapability.

5.

The first address on any port must be a multiple of hex 10. For example: 0A1

0,0E

2

0, and 2F3

0.

CKD assignment change: EMC restrictions

Map/Unmap operations will be blocked for configurations that do not follow thepreceding rules.

If a configuration is split on a port level (this is only possible i f there is no PAV inthe box), then it cannot be unsplit on the EA interface with the interface online. Ifthe A and B port addressing is different, and if that situation needs to be resolvedto introduce PAV devices, both ports will need to be taken offline for theconfiguration change.


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CKD assignment change: z/OS restrictions

The following restrictions are z/OS limits, and not EMC limitations.

Before an alias can be removed in a static PAV environment, the base associatedwith that alias must be varied offline from the host. If the base is offline, the basecan be removed as well, however, do not leave a configuration that conflicts with

rule 5 on page 18. Before an alias can be removed in a DPAV environment, either with or without

removing the base, the entire CU image thatthe alias is associated with must beoffline. This is necessary because there is no way to predict the current base/aliaslocations of any alias under DPAV. Remember, the bin is just the start-up position.A display may show a base with the same number of aliases as there were atstartup, but they may be aliases that have moved from other bases during thecourse of the DPAV changes. There is no way to reconcile the DPAV moves with thestatic bin file being loaded. So the whole CU image must start again after theconfiguration change. This means the CU image must be offline for the change,and when it comes back online, the DPAV process can start again from the

beginning with the new information. If you are removing bases and aliases, do notcreate a configuration that conflicts with rule 5 on page 18.

The Hardware Control Definition (HCD) must match Symmetrix changes.

Conclusion

Unisphere for VMAX is a storage-management tool that delivers easy and intuitiveSymmetrix array management. Intelligence is built into Unisphere to guide the usertowards selecting the appropriate object within the array hierarchy before initiating acommand sequence. Array properties can be viewed, and array configuration changescan be initiated and managed. Users of all experience levels will find this tool helpful

as templates and dialog boxes streamline parameter entry and make tasks easy andefficient. Mainframe-specific configuration tasks are available under the z/OSConfiguration menu item. These Mainframe items are intended to allow storageadministrators to perform CKD-specific configuration changes on Symmetrix arrays.Enabling authorized storage administrators to directly perform array modificationsreduces complexity and improves time frames for activities administered underchange control systems. Unisphere provides ease and simplicity for currentfunctionality, and Unisphere will deliver the same intuitive constructs for any futurefunctionality, lessening the learning curve when implementing new technology.

References

The following manuals and references provide information related to conceptsdiscussed in this paper:

EMC Unisphere for VMAX Release Notes

EMC Unisphere for VMAX Online Help


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EMC Unisphere for VMAX Product Guide

EMC Unisphere for VMAX Installation Guide

EMC Solutions Enabler Symmetrix Array Controls CLI Product Guide

EMC Solutions Enabler Symmetrix Array Management CLI Product Guide

EMC Solutions Enabler Symmetrix CLI Command Reference IBM z/OS V1R13 MVS System Commands

Refer to support.emc.com for the latest Unisphere and Symmetrix releasedocumentation and product release notes.


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Appendix

Z series hardware complex

Although Unisphere only reports on and manages Symmetrix arrays, it is important to

understand the position of an array within the hardware hierarchy of z/OS. Thefollowing z/OS connectivity example is a typical high-availability configuration. Thereare many hardware elements and logical layers involved in delivering an I/Ooperation from the Mainframe host to the Symmetrix array.

In Figure 14, Symmetrix devices in CU image 1A are defined on 4 x FICON directors(EF's). The CU image is identifiable by way of the channel address of the base devicesbeing 1Axx. The FICON directors are connected by means of 2 x FICON switches into 8x CHPIDs. There are several logical layers shown in the diagram that exist between theCHIPIDs and the UCBs mapped to Logical Channel Subsystem (LCSS) 0/1 of the z9,z10, z114, or z196 complex. The four Symmetrix EF directors form a single LogicalPath Group to CU image 1A.

Figure 14. Z series hardware complex


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LCSS Logical Channel SubSystemLPAR Logical PartitionMIF Multiple Image FacilityMSS Multiple Subchannel SetCHPID Channel Path IDPCHID Physical Channel ID

Example of HCD configuration parameters

It is important that Unisphere users are conversant with the hardware and softwareconfigurations of the z/OS environment before implementing Symmetrix resourcechanges. Unisphere initiated configuration changes are validated by SymmWin toensure conformance with internal Symmetrix data structures. These Symmetrixchecks extend to some but not all of the online requirements of the z/OS operatingsystem. Unisphere users are encouraged to participate in the appropriate changecontrol processes to assure adherence to site resource planning.

Symmetrix configuration definitions for CU image numbering and device addressingfor both base and aliases must match the Hardware Control Definition (HCD).

The extract shown in Figure 15 is from a typical HCD configuration. The CNTLUNIT andIODEVICE statements provide indicators of resources that Unisphere has the ability toinfluence. Key points of interest for Unisphere users are the UNITADD, CUADDnumber, PATH and LINK, IODEVICE base devices, and associated alias-addressingrange statements.

CHPI D PATH=( CSS( 1) , 98) , SHARED,PARTI TI ON=( (0), (V11A, V118, V119) ) ,SWITCH=7E, PCHI D=1E1,

TYPE=FC

CHPI D PATH=( CSS( 1) , 99) , SHARED,PARTI TI ON=( (0) , (V11A, V118, V119) ) , SWI TCH=7E, PCHI D=1F1,

CNTLUNI T CUNUMBR=13DA,PATH=( (CSS(1),98,99) ) , *UNITADD=((00,256) ) ,LINK=( (CSS(1),7E21,7E22) ) ,CUADD=1A,UNI T=2105

IODEVICE ADDRESS=(1A00,224) , CUNUMBR=( 13DA) , STADET=Y, UNIT=3390B

IODEVICE ADDRESS=(1AE0,032) , CUNUMBR=( 13DA), STADET=Y, SCHSET=1,UNIT=3390A

Figure 5. Example HCD definition

Parallel Access Volumes

Parallel Access Volume (PAV) technology allows a single z/OS host to simultaneouslyprocess multiple I/O operations to the same logical volume. Prior to PAV capability,Unit Control Blocks (UCBs) and z/OS queues kept track of I/O requests that wereprocessed serially. With PAV-enabled devices, instead of one UCB per logical device,a z/OS host can use a base UCB, and several alias UCBs, to access the same logicaldevice, as long as I/O is not writing to the same device extent.

Figure 16 shows a representation of multiple UCBs for the same PAV-enabled logicaldevice through the assignment of a base channel address (000) and two-channelalias addresses (080 and 0C0).


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Figure16. Multiple addresses for a PAV enabled device

A base device is a real device represented by a Symmetrix logical volume, as well as

by a UCB in the host. A base device uses a real channel address and consumes realspace on the back-end disks of the CU. An alias device is also represented by a UCBin the host, uses a real channel address, but while defined in the CU, consumes noreal disk space and has no Symmetrix logical volume number.

Symmetrix Dynamic PAV feature allows the Workload Manager (WLM) component ofz/OS to dynamically reassign/remove alias devices (donor) to or from different basedevices (receivers) depending on the performance needs of the workload at aparticular time. The I/O Supervisor uses these WLM-allocated alternative UCBs toperform multiple I/O operations to the same device.

With dynamic PAV, the total set of aliases for a CU image is treated as a pool. The

WLM component of z/OS works with the Symmetrix system to allocate aliases todevices based on performance-selection criteria. Devices reaching performance limitsare allocated aliases automatically according to the current workload schedulingdemands. This allocation provides the best PAV device performance, without puttingthe allocation burden upon the human administrator.

Multiple Allegiance (MA) is a CU capability that allows the parallel processing of non-conflicting I/Os from multiple z/OS hosts (as opposed to PAV, which is parallel I/Ofrom the same host). Multiple Allegiance I/O executes concurrently with PAV I/O. TheSymmetrix array treats them equally and guarantees data integrity by serializing writeI/Os where extent conflicts exist.

PAV discovery is an event that occurs during the z/OS device Vary online process;detecting the availability or unavailability of an alias association with the basedevice. Dynamically removing and assigning alias devices under Unisphere maynecessitate the use of applicable z/OS system commands (or IODF or both) to ensuresynchronization of the host and Symmetrix configurations for base/aliasrelationships.


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When setting up base/alias addressing assignments within a 256-device addressingrange, base addresses must be in the low end of the range and alias addresses in arange above the base addresses. Typically, base addresses begin at 00 and ascend,and alias addresses begin at FF and descend.

Planning addresses for static PAV

When setting static PAV, a fixed relationship between a base device and its alias iscreated. Workload Manager cannot reassign a static alias to a different base device.

Table 1 shows the most common layout when two alias addresses are staticallyassigned to 64 base devices within a CU. The base addresses for these devices are000 to 03F. The number of aliases required is 128. The high-end alias device range is0C0 to 0FF and 080 to 0BF, (working from FF backwards down the range.) Theremaining device addresses in the range 040 to 07F can be used as base devices withno aliases.

Base Alias #1 Alias #2

000 080 0C0

001 081 0C1

002 082 0C2

003 083 0C3

03F 0BF 0FF

040

041

07F

Table 1. 64 base devices with two aliases for each

If you intend to assign alias addresses to base devices 040 to 04F sometime in thefuture, careful planning is required. Observing the rule that base addresses begin at00 ascending and alias addresses begin at FF descending, prevents difficulty withconflicting base and alias ranges. The final result is shown in Table 2.

Base Alias #1 Alias #2

040 060 070

041 061 071

042 062 072

043 063 073

04F 06F 07F

Table 2. Adding two aliases to base devices 040 to 04F


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Adding three aliases each for base devices 040 to 04F would complete the 256address capacity of the CU. Additional addressing would need to use another CUimage. Table 3 shows how adding three aliases to base devices 040 to 04F completesthe CU. This CU now has two static aliases on devices 00-34 and three static aliaseson devices 40-4F. The base range is 00-7F, and the alias range is 80-FF. The base andalias ranges cannot cross each other, and this layout has achieved that goal.

Base Alias #1 Alias #2 Alias #3

040 050 060 070

041 051 061 071

042 052 062 072

043 053 063 073

04F 05F 06F 07F

Table 3. Adding three aliases for each base device 040 to 04F

Assigning three alias addresses for each of the 64 base devices within the 256-deviceaddressing range of a CU is a natural division and would complete the addressingwithin the CU, as Table 4 illustrates. (64 base addresses and 192 alias addresses,uses 256 addresses in an even distribution.)

Base Alias #1 Alias #2 Alias #3

000 040 080 0C0

001 041 081 0C1

002 042 082 0C2

003 043 083 0C3

03F 07F 0BF 0FF

Table 4. Adding three aliases for each 64 base devices

Note

: Once an addressing configuration is set up for a Symmetrix array, any change

made to the mix of addresses requires management work on the host (IOCDS), whichcould be highly disruptive. All involved devices, perhaps an entire CU image, mayhave to be taken offline during some address reassignments.


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Planning addresses for dynamic PAV

Setting dynamic PAV operation allows the Workload Manager (WLM) component ofz/OS to dynamically reassign alias devices to different base devices depending onthe performance needs of the workload at a particular time. Although WLM managesthe alias devices dynamically and changes base/alias assignments on the fly, theinitial allocation of alias addresses to base devices needs to be established. The

operating system can revert back to this initial allocation if dynamic managementencounters an error. Even in a dynamic environment, the Symmetrix array mustpresent an initial base/alias allocation to the host.

Table 5 is an example of assigning 128 alias addresses to 128 base devices in a CU.Once the Symmetrix array is brought online to the z/OS host, WLM will dynamicallymove base/alias relationships as indicated by the workload.

Base Alias

000 080

001 081

002 082

03F 0BF

040 0C0

041 0C1

07E 07E

07F 0FF

Table 5. Adding one alias for each dynamic PAV device

h11631 Using Unisphere Vmax Manage Symmetrix Ckd Devices Os Environment Wp

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