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DYNAMIC OPTIONS

This section contains an alphabetic list of the Dynamic Options attributes. The list includes a description of each attribute, its valid values, and the CA Vtape features it supports.

While active, the CA Vtape subsystem can dynamically reload the Dynamic Options attributes by using the following operator command:

SVTn REFRESH=OPTION

The following is an alphabetic list of the Dynamic Options attributes:

AllowBTEencryptionForVVE=

Determines when Virtual Volumes are eligible for encryption by CA Tape Encryption.

Valid Values:

Default: Y

Feature: Virtual Device Engine

BackstoreRetryCount=

Determines the number of Externalization attempts that will be made before a Virtual Volume is dequeued from the subgroup queues without being Externalized.

Valid Values:

Note: We recommend a setting of 20, which will allow 20 attempts over a 20-minute period before a Virtual Volume is dequeued. Since the primary reason for an Externalization failure is the Virtual Volume being remounted by an application, a 20-minute delay will allow most applications enough time to complete their processing and release the Virtual Volume. If applications exist that continuously remount a Virtual Volume, then a higher BackstoreRetryCount value is needed.

Default: -1

Feature: Backstore Engine

BypassRLLCompression=

Determines if Run Length Limited (RLL) compression, accessed through the IBM CSRCESRV service, should be bypassed.

Valid Values:

Default: Y

Feature: DASD Buffer Compression

CacheAutoHoldLowThreshold=

Determines at what percentage of Cache-In-Use Subgroup Automation should hold automated subgroup queues. Manual subgroup queues are not affected.

If the CacheWarningThreshold or the CacheAutoHighReleaseThreshold attributes are set to zero, this attribute is not active.

This attribute's value must be less than the CacheAutoHighReleaseThreshold value unless both are set to zero.

Note: For more information about Subgroup Automation, see the chapter “Operational Considerations.”

Valid Values: 0 to 100

Default: 0

Feature: Backstore Engine

CacheAutomationSchedule=

Determines the time periods when Subgroup Automation is allowed to release the subgroup queues for automated subgroups. Manual subgroup queues are not affected.

If the CacheWarningThreshold or the CacheAutoHighReleaseThreshold attributes are set to zero, this attribute is not active.

Up to four time periods separated by commas can be coded. For example:

CacheAutomationSchedule = (00:00-03:00,06:00-09:00,12:00-15:00,18:00-21:00)

The time periods coded must not overlap.

Outside of the time periods coded, the subgroup queues for automated subgroups will be held. When a time period ends, any automated subgroup queue that is released or active will be held. The hold will occur within one minute of the ending time period. For example, if a time period ends at 03:00 all automated subgroup queues will be held and any active Externalization tasks for those queues will be gracefully stopped between 03:00 and 03:01.

Note: For more information about Subgroup Automation, see the chapter “Operational Considerations.”

Valid Values:

Default: (00:00-23:59)

Feature: Backstore Engine

CacheAutoReleaseHighThreshold=

Determines at what percentage of Cache-In-Use Subgroup Automation should release automated subgroup queues. Manual subgroup queues are not affected.

Valid Values:

If the CacheWarningThreshold is set to zero, this attribute is not active.

This attribute's value must be greater than the CacheAutoHoldLowThreshold value unless both are set to zero.

Note: For more information about Subgroup Automation, see the chapter “Operational Considerations.”

Default: 0

Feature: Backstore Engine

CacheFreespaceThreshold=

Determines at what percentage of physical allocations in cache CA Vtape will start deleting Externalized Virtual Volumes from cache. A setting of 90 indicates that when the physical allocations in cache reach 90%, Externalized Virtual Volumes should be deleted from cache. CA Vtape will attempt to maintain 10% of the cache free at all times to support scratch mounts and recalls.

Maintaining this free space eliminates the need to free up space during mount processing. By eliminating space management actions from mount processing, the mount can proceed without delay.

Lowering the setting has the following positive effects:

Lowering the setting has the following negative effects:

The setting is typically lowered when you have a number of jobs being submitted at the same time that require large amounts of cache space. For example, if you have multiple backup jobs being submitted at the same time that will write large amounts of data to Virtual Volumes, lowering the setting or increasing the cache size will be necessary to prevent slower mounts and warning messages about momentary cache shortages while CA Vtape is deleting Virtual Volumes from cache.

The 90% setting has been found to be satisfactory at the majority of customer sites.

Observe the following:

Valid Values: 0 to 100

Default: 90

Feature: Miscellaneous

CachePrimary=

Specifies the Primary space allocation, in MB, used for dynamically allocated Virtual Volume data sets.

The recommended value for this attribute is 1/10th of the Virtual Volume size, for example: 40, 80, or 200.

Valid Values: 24 to 2000

Default: 200

Section: <DynamicOptions>

Feature: Miscellaneous

CacheSecondary=

Specifies the Secondary space allocation, in MB, used for dynamically allocated Virtual Volume data sets.

The recommended value for this attribute is 1/10th of the Virtual Volume size, for example: 40, 80, or 200.

Valid Values: 24 to 2000

Default: 200

Feature: Miscellaneous

CacheWarningThreshold=

Determines the percentage of Cache-In-Use at which the SVTnD0908I message is issued to warn of a potential cache shortage.

Valid Values:

Note: For more information about Subgroup Automation, see the chapter “Operational Considerations.”

Default: -1

Feature: Backstore Engine

CatalogManagedDate=

Identifies the date value used to place a tape under catalog management or catalog retention control in the tape management system. This value is used by the Backstore Engine and Recycle to determine which Virtual Volumes will be assigned to the subgroup defined by the group CatalogManagedSubgroup attribute. It is also used by the Backstore Engine and Recycle to place the Backstore Physical Tapes under catalog retention control.

Valid Values:

Default: -1

Features: Subgroup Assignment and Tape Management

ConsoleCommandTimeout=

Controls the number of seconds before console commands timeout and WTOR SVTnD9920I is issued.

Note: We recommend a setting of 60, which will allow 60 seconds for the CA Vtape console command to be executed before the WTOR is issued.

Valid Values: 30 to 600

Default: 300

Feature: Miscellaneous

DefaultGroup=

Controls the group number assigned to a Virtual Volume when the data set cannot be identified based on data class or data set name filter. One example of this is when a Virtual Volume is mounted on Virtual Device by a specific unit allocation, that is:

    //DD1 DD UNIT=/3455,DISP=(NEW,KEEP),..

Valid Values: GROUP01, GROUP02, GROUP03,… to GROUP74

Default: GROUP01

Feature: Backstore Engine / Recycle

ForeignTapesExpdt=

Determines the expiration date value that will cause CA Vtape to bypass a mount request for a VOLSER that matches a CA Vtape Virtual Volume, but is not a CA Vtape Virtual Volume. For example, assume your Virtual Volume range is V00000-V99999 and a vendor ships you a tape with a VOLSER of V15000. If a job is run to read the tape using an esoteric that includes the CA Vtape virtual devices, CA Vtape will try to intercept the mount. Adding LABEL=EXPDT=value, where value is that of the ForeignTapesExpdt attribute, to the DD statement in the JCL will cause CA Vtape to bypass or ignore the mount request.

Note: Changing the DD statement UNIT parameter to an esoteric or generic that does not include the CA Vtape virtual devices will also cause CA Vtape to bypass or ignore the mount request.

Valid Values:

Default: 00000 or '1900/000'

Feature: Miscellaneous

FullMaxdrivesEnforcement=

Determines if physical tape drives used by Recall tasks should be counted when enforcing the MAXDRIVES setting.

Note: If MAXDRIVES is set to zero and FullMaxdrivesEnforcement is set to Y(es), no Externalization or Recall tasks will be started. FullMaxdrivesEnforcement=Y and MAXDRIVES=0 are the requirements to designate a CA Vtape subsystem as a Failover Backstore Engine Server.

When enforcing the MAXDRIVES setting the Backstore Engine will stop Externalization tasks to free physical tape drives, but will not stop Recall tasks.

Valid Values:

Default: Y

Feature: Backstore Engine

GlobalReserve=

Determines whether the Global VCAT reserve is issued with a QNAME.RNAME of “SVTS.GLOBAL” or “SVTS.Global VCAT data set name”.

Valid Values:

Default: Compatibility

Feature: Miscellaneous

HardwareCompressionMethod=

Determines which compression methods can be employed when compression is active and compression is to be used for data written onto a Virtual Volume in the DASD buffer.

Valid Values:

Note: More than one compression method can be specified for HardwareCompressionMethod by separating each method using a comma.

For example:

HardwareCompressionMethod= CMPSC,RLL
HardwareCompressionMethod= LZ78,RLL

When more than one compression method is employed, CA Vtape automatically monitors each method and chooses the method achieving the highest compression rate for a given virtual volume.

Default: $NULL

Feature: DASD Buffer Compression

HardwareCompressionOption=

Determines if compression should be performed on data written to Virtual Volumes in the DASD buffer.

Valid Values:

Note: For more information about Virtual Volume Compression, see the chapter “Operational Considerations.”

Default: N

Feature: DASD Buffer Compression

IOCpuTimeout=

Determines the number of CPU seconds allowed for each I/O before it is terminated by the operating system with abend code S05B. This prevents the Virtual Device Engine from looping.

Valid Values: 5 to 300

Default: 15

Feature: Virtual Device Engine

LogDetailLevel=

Determines the level of detail of internal processes that is recorded by the Logger.

Valid Values:

LogDetailLevel=2 and 3 may generate a large volume of records on an LPAR with a very active CA Vtape subsystem.

HLQ.CCUUJCL(LOGEVENT) contains complete descriptions of what events are logged and the detail level they are logged at.

Default: 1

Feature: Logger

LogStream=

Determines whether the data generated by the Logger is copied from the CA Vtape log dataspace to an IBM system Log Stream data set. This is referred to as the External Logger.

Valid Values:

Note: The only valid Log Stream name is one that was created using the IBM IXCMIAPU utility. You can use the SVTn Display Log console command to determine the status of the logger.

Default: NONE

Feature: Logger

MaximumCompressionCPU=

Determines the maximum amount of data that will be compressed in each 50 MB segment of data written to a Virtual Volume. This percentage is directly related to the amount of CPU used by compression. If, for example, this percentage is set to 75, only 75% of the data written will be compressed and only 75% of the CPU that would have been used by compression is actually used.

Valid Values:

Note: For more information about Virtual Volume Compression, see the chapter “Operational Considerations.”

Default: 100

Feature: DASD Buffer Compression

MinimumCompressionRate=

Determines the minimum compression percentage that must be achieved to continue compressing a 50 MB segment of a Virtual Volume being written. Compression is tested every 50 MBs of each Virtual Volume to determine the best compression method to use.

Valid Values:

Note: For more information about Virtual Volume Compression, see the chapter “Operational Considerations.”

Feature: DASD Buffer Compression

MountRejectThreshold=

Determines the action taken when the tape management system rejects a scratch mount.

Valid Values:

Note: Cancel,10 is the recommended setting.

Default: IGNORE

Feature: Virtual Device Engine

NeverExpireDate=

Identifies the date value used to place a tape under never-expire or permanent retention control in the tape management system.

This value is used by the Backstore Engine and Recycle to determine which Virtual Volumes will be assigned to the subgroup defined by the group NeverExpireSubgroup attribute.

Note: The value used must match the tape management system permanent or never-expire date. The value used must not match the values coded for the ForeignTapesExpdt, CatalogManagedDate, and SpecialRetentionDate attributes.

Valid Values: A valid date in yyddd or 'yyyy/ddd' format

Default: 99365 or '1999/365'

Feature: Subgroup Assignment

PercentRunOnZIIP=

Specifies the percentage of work to be made eligible for the zIIP processor. In the Startup Options Section, attribute zIIPExploitation= must be set to Y to cause PercentRunOnZIIP to take effect. If PercentRunOnZIIP= is nonzero but zIIPExploitation=N is specified an error message will be issued but CA Vtape will continue to initialize and run without zIIP processing activated.

Valid Values:

Default: 0

Feature: Virtual Device Engine

RealStorageSafetyThreshold=

Specifies the percentage which the z/OS available central storage satisfactory threshold should be multiplied by to determine the point at which CA Vtape should defer mount and backstore processing to help z/OS maintain a healthy central storage environment.

z/OS maintains two fields which are used to determine the health of its central or real storage. The fields are RCEAFCLO and RCEAFCOK in the RCE control block. RCEAFCLO is the available central storage low threshold. Reaching this point indicates to z/OS that aggressive actions must be automatically taken to prevent a real storage constraint from impacting the system. RCEAFCOK is the available central storage satisfactory threshold or safety point. Reaching this point indicates to z/OS that aggressive actions are no longer required because the real storage constraint has been relieved.

CA Vtape dynamically acquires real storage for its active virtual devices and for externalization subtasks. As this activity increases, especially in a larger installation with lots of virtual devices being used concurrently, the amount of real storage usage could cause the available real storage to drop below the safety point. The RealStorageSafetyThreshold allows you to tell CA Vtape when to stop acquiring real storage to ensure that the CA Vtape does not cause real storage usage to go lower than the safety point.

For instance, the default of 400% implies that CA Vtape will keep a mount in pending status or defer the Backstore of a subgroup queue if the storage that needs to be acquired will reduce the available real storage to within 400% of the safety point. As other tasks that do not control themselves might be requesting real storage at the same time, the default of 400% is a conservative value to delay CA Vtape real storage requests well before z/OS experiences real storage stress. The default value should be lowered if you see CA Vtape delaying mounts on a system where a storage constrain is not occurring.

If the attribute value is set too high, CA Vtape will issue the SVTnV5008I message delaying new Virtual Mount requests or the SVTnP1708I message delaying new Externalization requests or both and appear to hang. Previous mounts will continue to be processed. Previous Externalization requests will continue to be processed. Only new requests will be delayed. When previous requests complete and free their storage, a new Virtual Mount request or a new Externalization request will be started unless the freed storage is consumed by some other task. Lowering the attribute value and issuing the SVTn REFRESH=OPTIONS console command for each CA Vtape subsystem which needs to pick up the change will eliminate the delays.

To disable this feature, specify a value of 0.

Valid Values: 0 to 900

Default: 400

Feature: Miscellaneous

RecallNotificationEvent=

Determines the mode of communication between a Recall Server and its clients.

Valid Values:

Default: TIMED,n

Feature: Backstore Engine

RecallServer=

Determines whether the Backstore Engine for a CA Vtape subsystem processes its own Recall requests, processes all Recall requests for its CA Vtape Complex, or notifies another subsystem in the complex so it can perform the Recall requests.

Valid Values:

Note: We recommend that you configure as the Recall Server in a CA Vtape Complex the same subsystem that is configured as the Primary Externalization Server. This will minimize physical tape and drive contention for Externalization and Recall requests.

Default: COMPATIBILITY

Feature: Backstore Engine

RecallServerTimeout=

Determines the number of seconds a subsystem will wait before issuing a critical alert message that a Recall request is not being processed. The value should be set high enough to not issue unnecessary alert messages when a Recall request is delayed due to contention for physical tape drives.

Valid Values:

Feature: Backstore Engine

ScratchReuseDelay=

This attribute Influences the number of days to delay the reuse of a scratched virtual volume. For example, a virtual volume scratched today should not be considered to satisfy a new scratch mount request until (n) days have elapsed.

If the attribute value cannot be honored because there are no n day old scratches available the subsystem will take the following actions:

Note: For a P2P scratch mount, the attribute setting in the remote server determines the reuse delay. Also, the temporary override of the attribute value is not performed.

Valid Values: 0 to 128

Default:5

Feature: VirtualDeviceEngine

ScratchVolumesThreshold=

Determines whether the SVTnD0928W message is issued every 30 minutes when the number of available scratch Virtual Volumes drops below the specified value.

Valid Values:

Default: 0

Feature: Virtual Device Engine

SpecialRetentionDate=

Indentifies a range of date values used to place a tape under special retention control in the tape management system.

These values are used by the Backstore Engine and Recycle to determine which Virtual Volumes will be assigned to the subgroup defined by the group SpecialRetentionSubgroup attribute.

Note: The value used must match the tape management system special retention dates. The values used must not match the values coded for the ForeignTapesExpdt, CatalogManagedDate, and NeverExpireDate attributes.

Valid Values: A valid date range in 'yyddd-yyddd' or 'yyyy/ddd-yyyddd' format

Default: '99001-99001' or '1999/001-1999/001'

Feature: Subgroup Assignment

TapeManagementSystem=

Determines if the interface to the CA 1 or CA TLMS tape management systems is active. The interface allows CA Vtape to query the tape management system to determine the current expiration date (remaining retention) of a Virtual Volume. This allows Externalization and Recycle to reduce fragmentation on the Backstore Physical Tapes by assigning a Virtual Volume to a subgroup based on its true retention rather than what was specified in the JCL, which wrote the Virtual Volume. The interface also allows CA Vtape to update the Virtual Volume record Container field in the tape management system with the physical tape volser on which the virtual was stacked. The Container field provides a direct link in the tape management system between the application data set on a Virtual Volume and a physical tape for reporting and auditing purposes and for off-site movement.

Valid Values:

Default: NONE

Feature: Subgroup Assignment and Tape Management