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:
Determines when Virtual Volumes are eligible for encryption by CA Tape Encryption. CA Tape Encryption is a separately licensed product.
Valid Values:
Virtual Volumes are not eligible for encryption.
Virtual Volumes are eligible for encryption.
Default: Y
Feature: Virtual Device Engine
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
Feature: Miscellaneous
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
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 a CA Vtape console command to be executed before the WTOR is issued.
Valid Values: 30 to 600
Default: 300
Feature: Miscellaneous
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: Miscellaneous
Determines the expiration date value that will cause CA Vtape to bypass a mount request for a VOLSER that matches a 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:
Indicates that the feature is turned off or disabled.
Indicates the date value to use. 99365, 99366, '1999/365', and '1999/366' (never-expire dates) are all reserved values that will generate a validation error if used for this attribute.
Default: 00000 or '1900/000'
Feature: Miscellaneous
Determines whether the Global VCAT reserve is issued with a QNAME.RNAME of “SVTS.GLOBAL” or “SVTS.Global VCAT data set name”.
Valid Values:
Indicates that GLOBAL will be used for the reserve RNAME. This allows backward compatibility with subsystems running at Release 2.0 SP05 or prior maintenance.
Important! The use of this generic enqueue reserve RNAME instead of the actual Global VCAT name, will cause contention and a performance penalty between CA Vtape complexes. When one complex issues the generic reserve to update its Global VCAT, other complexes will have to wait to issue the reserve to update their Global VCAT. Even though the different complexes are using different Global VCATs, updates will be serialized across all complexes.
Indicates that the Global VCAT name will be used for the reserve RNAME. This will prevent contention between multiple CA Vtape Complexes, by issuing the Global VCAT reserve with a reserve name unique to the Global VCAT. In this mode all subsystems in all CA Vtape Complexes must be running in enhanced mode. If a back-leveled or compatibility mode subsystem is detected, enhanced mode subsystems will issue messages and change to compatibility mode.
Default: Enhanced
Feature: Miscellaneous
Determines which compression methods can be employed when compression is active and compression is to be used for data written to a Virtual Volume.
Valid Values:
$NULL is a compatibility setting that causes this attribute to be ignored. If compression is activated and this attribute is set to $NULL, CA Vtape utilizes RLL and CMPSC compression. LZ78 is not employed.
CMPSC is the hardware compression call instruction. This method employs several compression dictionaries to achieve moderate compression rates with less CPU overhead than LZ78.
RLL (Run Length Limited) is a software implementation which compresses data by eliminating repeating characters. This method can sometimes achieve good compression with low CPU overhead.
LZ78 (Lepel-Ziv-78) is a software implementation. This method utilizes an adaptive compression algorithm which can achieve higher compression rate but at much higher CPU rates than CMPSC or RLL.
ALL indicates that all of the compression methods mentioned above except $NULL should be used. That is, CMPSC, RLL, and LZ78 are all used.
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: ALL
Feature: Virtual Volume Compression
Determines if compression should be performed on data written to Virtual Volumes. If the network storage being used already performs compression, this option should be set to N.
Valid Values:
Indicates that compression should never be performed.
Indicates that compression should always be performed.
Indicates that compression should be performed if TRTCH=COMP is coded in the JCL or if COMPACT=YES was used when defining the Virtual Devices. If TRTCH=NOCOMP is coded, compression will not be performed.
Indicates that the Group Definitions should be checked for one of the above three values.
Note: For more information about Virtual Volume Compression, see the chapter “Virtual Device Engine.”
Default: N
Feature: Virtual Volume Compression
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
Determines the level of detail of internal processes that is recorded by the Logger.
Valid Values:
Indicates that no logging should be done.
Indicates that basic events like messages issued, console commands issued, batch utilities executed, recovery errors, subtask attach/detach, and major routines entered should be logged. This is the recommended setting unless additional log detail is needed to diagnose a problem.
Indicates that in addition to level 1 details, subchannel commands, interrupt commands, and low-level routines entered should be logged.
Indicates that in addition to level 2 details, detailed I/O information should be logged.
LogDetailLevel=2 and 3 may generate a large volume of records on an LPAR with a very active Subsystem.
HLQ.CCUUJCL(LOGEVENT) contains complete descriptions of what events are logged and the detail level they are logged at.
Default: 1
Feature: Logger
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:
Indicates that a Log Stream does not exist so a copy will not be performed. The Logger will overwrite the data generated previously in the log dataspace.
Indicates that a Log Stream does exist. As each block in the log dataspace is filled, a call is made to the System Logger to write the block to the defined Log Stream. If errors are detected, the System Logger and CA Vtape will issue messages and this attribute will be internally changed to a value of NONE.
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
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:
Indicates that no data should be compressed. This setting should only be used temporarily. If compression should be turned off permanently, use the HardwareCompressionOption attribute.
Indicates the actual percentage of data written that should be compressed. If set to 50, only 50% of each 50 MBs of data written to a Virtual Volume will be compressed.
Indicates compress all the data written.
Note: For more information about Virtual Volume Compression, see the chapter “Virtual Device Engine.”
Default: 100
Feature: Virtual Volume Compression
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:
Indicates that this check is disabled. Any achieved percentage compression or no compression will allow compression to continue.
Indicates the percent of compression that must be achieved to continue compressing each 50 MB segment of a Virtual Volume.
Note: For more information about Virtual Volume Compression, see the chapter “Virtual Device Engine.”
Feature: Virtual Volume Compression
Determines the action taken when the tape management system rejects a scratch mount.
Valid Values:
Indicates that no action will be taken. CA Vtape will continue selecting Virtual VOLSERs from the scratch pool until one is accepted by the tape management system or the pool is empty. This could lead to a scratch shortage.
Where nn is between 05 and 99, indicates that after nn VOLSERs are rejected for this mount request a WTOR should be issued. The resulting SVTnV1803W message asks the operator whether the job should be cancelled or whether the Mount Reject Policy should be ignored.
Where nn is between 05 and 99, indicates that after nn VOLSERs are rejected for this mount request the job should be cancelled.
Note: Cancel,10 is the recommended setting.
Default: IGNORE
Feature: Virtual Device Engine
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 and CA Vtape will run without zIIP processing activated.
Valid Values:
Specifies that no work is to be directed to the zIIP processor. It is valid to specify PercentRunOnZIIP=0 and zIIPExploitation=Y at the same time. In this case, CA Vtape will issue warning message SVTnI0009W but will go on to build and maintain the internal resources required to use the zIIP processor but no work will be made zIIP eligible until a nonzero value is specified and the dynamic options are refreshed using the SVTn REFRESH=OPTIONS command.
Specifies the percentage of work that is to be made eligible for the zIIP processor. A value of 100 is recommended to take full advantage of the zIIP processor. You can use IBM's WLM to prioritize which products are eligible for the zIIP processor.
Default: 100
Feature: Virtual Device Engine
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 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. 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 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 constraint is not occurring.
If the attribute value is set too high, CA Vtape will issue the SVTnV5008I message delaying new Virtual Mount requests and appear to hang. Previous mounts will continue to be processed. Only new requests will be delayed. When previous requests complete and free their storage, a new Virtual Mount 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
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:
Valid Values: 0 to 128
Default:5
Feature: Virtual Device Engine
Determines whether an SVTnD0928W message is issued every 30 minutes when the number of available scratch Virtual Volumes drops below the specified value.
Valid Values:
Indicates that the available scratch Virtual Volumes are not being monitored. The warning message will never be issued.
Indicates the scratch Virtual Volume threshold value. When the number of scratch Virtual Volumes falls below the specified value, the warning message will be issued. The message is reissued every 30 minutes as long as the number of scratch Virtual Volumes remains below the threshold value.
Default: 0
Feature: Virtual Device Engine
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