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
This 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 allows 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 that is assigned to a Virtual Volume when the data set cannot be identified based on data class or data set name filter. An example is a Virtual Volume that is mounted on Virtual Device by a specific unit allocation:
//DD1 DD UNIT=/3455,DISP=(NEW,KEEP),..
Valid Values: GROUP01, GROUP02, GROUP03,… to GROUP74
Default: GROUP01
Feature: Miscellaneous
Determines the expiration date value that causes CA Vtape to bypass a mount request for a VOLSER that matches a Virtual Volume. For example, assume that 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 tries to intercept the mount. To bypass or ignore the mount request, add the LABEL=EXPDT=value to the JCL DD statement. value is the ForeignTapesExpdt attribute value.
Note: Changing the DD statement UNIT parameter to an esoteric or generic that does not include the CA Vtape virtual devices also causes CA Vtape to bypass or ignore the mount request.
Valid Values:
Indicates that the feature is turned off or disabled.
Indicates the date value. 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 is 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, causes contention and a performance penalty between CA Vtape complexes. When a complex issues the generic reserve to update its Global VCAT, other complexes wait to issue the reserve to update their Global VCAT. Even though the different complexes are using different Global VCATs, updates are serialized across all complexes.
Indicates that the Global VCAT names that are used for the reserve RNAME. This prevents 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 issues messages and change to compatibility mode.
Default: Enhanced
Feature: Miscellaneous
Determines which compression methods can be employed when compression is active and compression is used for data that is 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 is performed on data that is 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 is never be performed.
Indicates that compression is always be performed.
Indicates that compression is erformed 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 is not performed.
Indicates that the Group Definitions are 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 the operating system terminates the I/O with ABEND code S05B. The timeout 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 the Logger records.
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. We recommend this setting unless you need more log detail to diagnose a problem.
Indicates that in addition to level 1 details, subchannel commands, interrupt commands, and low-level routines entered are logged.
Indicates that in addition to level 2 details, detailed I/O information are 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 does not occur. The Logger overwrites the data that is 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 issues messages and this attribute is internally changed to a value of NONE.
Note: The only valid Log Stream name is created using the IBM IXCMIAPU utility. 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 is compressed in each 50 MB segment of data that is 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 is compressed. Use this setting temporarily. If compression should be turned off permanently, use the HardwareCompressionOption attribute.
Indicates the actual percentage of data written that is compressed. If set to 50, only 50% of each 50 MBs of data written to a Virtual Volume will be compressed.
Indicates that all the data written data is compressed.
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 verification is disabled. Any achieved percentage compression or no compression allows 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 that the system takes when the tape management system rejects a scratch mount.
Valid Values:
Indicates that no action is taken. CA Vtape continues selecting Virtual VOLSERs from the scratch pool until the tape management accepts a VOLSER or the pool is empty. This setting can 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 is issued. The resulting SVTnV1803W message asks the operator whether the job is canceled or whether the Mount Reject Policy is ignored.
Where nn is between 05 and 99, indicates that after nn VOLSERs are rejected for this mount request the job is canceled.
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 directed to the zIIP processor. You can specify PercentRunOnZIIP=0 and zIIPExploitation=Y simultaneously. In this case, CA Vtape issues the warning message SVTnI0009W but builds and maintains the internal resources required to use the zIIP processor. However, no work is 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 made eligible for the zIIP processor. We recommend a value of 100 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 is multiplied by to determine the point at which CA Vtape defers 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 many virtual devices used concurrently, the amount of real storage usage can 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 CA Vtape does not cause real storage usage to go lower than the safety point.
For example, the default of 400% implies that CA Vtape keeps a mount in pending status if the storage that needs to be acquired reduces the available real storage to within 400% of the safety point. As other tasks that do not control themselves might be requesting real storage simultaneously, the default of 400% is a conservative value to delay CA Vtape real storage requests well before z/OS experiences real storage stress. If you see CA Vtape delaying mounts on a system where a storage constraint is not occurring, then lower the default value.
If the attribute value is set too high, CA Vtape issues the SVTnV5008I message delaying new Virtual Mount requests and appears to hang. The system continues to process previous mounts. Only new requests are delayed. When previous requests complete and free their storage, a new Virtual Mount request starts unless another task consumes the freed storage. Lowering the attribute value and issuing the SVTn REFRESH=OPTIONS console command for each CA Vtape subsystem that picks up the change eliminates 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, do consider a virtual volume scratched today also satisfies a new scratch mount request until (n) days have elapsed.
If the attribute value cannot be honored because no n day-old scratches are available, the subsystem takes 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 is never issued.
Indicates the scratch Virtual Volume threshold value. When the number of scratch Virtual Volumes falls below the specified value, the warning message is 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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