Optional parameters

The values are:

FULL

Specifies that XRC make a copy of each track of the primary volume onto the secondary volume at the same time that additional application updates are made to both copies. The volumes are initially in pending status and enter duplex state when the initial volume copy is completed.

QUICK

Specifies that XRC make a copy of only allocated tracks on the primary volume onto the secondary volume at the same time that additional application updates are made to both copies. XRC reads the VTOC of the primary volume to determine the allocated tracks on the volume. The volumes are initially in pending status and enter duplex state when the quick volume copy completes.

The default value is 8 MB. You can specify the value from zero (no permanent page-fixed storage) to 9999. Changes specified with the PAGEFIX parameter take place when the next set of storage control buffers are processed.

Attention: Unpredictable results can occur if you specify an amount of permanently page-fixed storage that exceeds or is near the limits of available processor storage. An IPL may be necessary.

The following values must be specified as noted when using the XSET PARMLIB command:

member_name

Specifies which parmlib member to read.

ACTION(action)

Specifies the type of action to perform. This can be:

• VERIFY, which performs a syntax check. This is the default.
• APPLY, which performs a syntax check, and if everything is correct, applies the parameters.

For information about limitations to using APPLY with changes to WorkloadWritePacing, refer to ANTXIN00 parmlib parameters.

DATASET(parmlib_dataset_name)

Specifies the parameter library to use. This field is optional. If you do not supply a value for this field and the specified session is active, XRC uses the data set that is set up when the XSTART command processes.

XRC requires this parameter if the session (session_id) is not an existing session.

The values are:

FIFO

Specifies that the system data mover select volumes in the order that is specified on the XADDPAIR command.

LOAD

Specifies that the system data mover select volumes whose primary storage control has the least load.

You can specify the XSET SCSYNCH parameter as SCSYNCH(p,s) or as SCSYNCH(n). The limit specified with n applies to both primary and secondary storage controls. You can specify a value between 0 and 45 for each variable (p,s, or n).

Set the SCSYNCH value in conjunction with the SYNCH parameter, which specifies the session limits for concurrent volume synchronization tasks. Changes specified with the SCSYNCH parameter take place when the next volume initialization is processed.

SUSLBUSY is mutually exclusive with TIMEOUT and REFRESHP. If SSID is also specified, the attributes of the storagecontrol sessions associated with the specified SSID's are immediately modified. If SSID is not specified, the global value for the session is modified. The global value is used for any new storage control session that is subsequently added.

If the storage control microcode supports the function, enabling will cause the microcode to automatically suspend the storage control session instead of raising extended long busy when sidefile limits are exceeded.

If the storage control microcode does not support the function, enabling will cause the data mover to suspend a storage control session as soon as it detects extended long busy due to sidefile exceeding limits. Storage control sessions that do not support suspension are terminated

Disabling allows the data mover to tolerate the long busy condition for 80% of the storage control session timeout interval, after which mirroring is suspended.

    { SYNCH * (number of volume pairs in CPY status) * 360K }

You can specify this parameter in hours, minutes, and seconds, can range from a minimum of one second (00.00.01) to a maximum of 18 hours (18.00.00). Specify TIMEOUT(STORAGE_CONTROL_DEFAULT) to request that XRC use the default set in the storage control, which is normally five minutes (00.05.00). Changes specified with the TIMEOUT parameter take place when you add a new storage control to the XRC session. You can also specify which storage subsystems are immediately affected by the TIMEOUT parameter, using the SSID parameter.

TIMEOUT is mutually exclusive with SUSLBUSY.

SSID

Specifies the SSIDs that the value specified on the TIMEOUT is applied to, thereby qualifying the scope of the TIMEOUT parameter.

If you do not specify the SSID parameter, then only storage controls that are added in the future will get the new timeout value. If you specify SSID(ALL), all current and future storage controls immediately get the new timeout value.

If you specify a specific set of SSIDs, only the listed storage controls immediately use the new timeout value. Storage controls that you add in the future will get the original timeout value, not the one specified in the TIMEOUT parameter.

You can specify up to nine SSIDs on a single XSET command. Specify each SSID with up to four character values. Separate each SSID by a comma or a blank.

FLOAT

Specifies the utility device for a storage control session will be selected by the storage control. FLOAT is the default.

FIX

Specifies the utility device for a storage control session is to be a specified (fixed) device.

Note: Be aware that issuing the XSET command with the UTILITY parameter specified does not activate or deactivate fixed utility device support. This support is enabled when you issue an XADDPAIR command with a secondary volser of XRCUTL.

Workload-based write pacing affects the behavior of DVCBLOCK. For more information, refer to Workload-based write pacing.

The DVCBLOCK values are:

ON

Specifies that device blocking is enabled for the specified volume(s).

When workload-based write pacing is in use, XRC automatically converts DVCBLOCK(ON) to DVCBLOCK(WPn), where n is the discretionary level, 6.

OFF

Specifies that device blocking is disabled for the specified volume(s). This is the default.

WPn

Specifies that write pacing is to be activated for the specified volume(s), with n specifying the level of write pacing delay, 0-F.

WP0 specifies that the session default level will be used, as specified the SHADOW DfltWritePacingLvl PARMLIB value.

WP1-WP7 result in pacing maximums of 0.02, 0.04, 0.1, 0.5, 1, and 2 milliseconds per recordset, respectively. These levels are useful for volumes with high rates of small blocksize writes, such as data base logs, where minimal response time impact is essential.

WP8-WPC result in pacing maximums of 5, 10, 25, 50, and 100 milliseconds per recordset, respectively. These levels are useful for volumes with high mb/sec write rates.

WPD-WPF result in pacing maximums of 200, 500, and 1000 milliseconds per recordset, respectively. These levels should be used only in exceptional situations where a very high degree of pacing is required.

Delay is injected per recordset, but a write channel program might create several recordsets. In such cases, the maximum possible delay per write channel program is equal to the pacing maximum multiplied by the number of recordsets that the channel program creates. For example, at pacing level WPC, a channel program that creates 4 recordsets can be delayed for a total of 4×100, or 400 milliseconds.

There is no overall limit on the amount of delay that can be injected for a channel program. Very large channel programs, such as those used in Sort applications, can experience delays measured in seconds when higher pacing levels are used.

The VOLUME values are:

volume_list

A list of 1 to 50 six-character volume serial numbers. Use either a blank of a comma to separate the serial numbers.

ALL

Specifies that all volumes in a session are to be changed. Message ANTX8131I will be issued indicating the total number of volumes for which the DVCBLOCK value was accepted.

ALLDP

All primary volumes specified as WP0 are to be changed.

ALLB

All primary volumes set to DVCBLOCK(ON) are to be changed.

ALLP

All primary volumes specified as WP1 - WPF are to be changed.

The system data mover doers not compare the data on the old and new volumes.

REFRESHP cannot be used with TIMEOUT.

The system data mover does not compare the data on the old and new volumes. You must ensure that the relocated secondary volume is identical to the original secondary at the time of suspension.

Using a combination of XRC commands, you can track which secondary volumes are relocated and where they were relocated:

1. Issue an XQUERY CONFIG request, redirecting it to a data set.
2. Issue XSET REFRESHS. You receive message ANTX8141I indicating number of volumes relocated.
3. Issue the XQUERY CONFIG request to redirect the data set to a different data set.
4. Compare the two XQUERY CONFIG data sets to find the relocated secondary volumes.