YKRESYNC (resynchronizes copy pairs)

Business Continuity Manager Web API Reference Guide

Version
9.9.1
Audience
anonymous
Part Number
MK-96HC137-03

Applies to ShadowImage, TrueCopy, and Universal Replicator.

This command resynchronizes copy pairs by differential copy for the specified copy group and changes the volume status to the DUPLEX status.

Request body format

{ "action":"submit",
   "cliname":"YKRESYNC",
   "operands":"
     [GROUP(copy-group-ID)]
     [△1SELECT({ALL|COND})]
     {[△1{QUICK|NORMAL}]  [△1{FORWARD|REVERSE}]
       [△1DEVN(p-vol-device-number, s-vol-device-number)] 
       [△1VOLUNIT[({LINEAR|DISPERSED})]]
     |△1DELTAJNL[△1ERRCHK[△1DEVN(p-vol-device-number, s-vol-device-number)]]
     |△1ALLJNL[△1ERRCHK[△1DEVN(p-vol-device-number, s-vol-device-number)]]
     |△1PREPARE
     }
     [△1ONLINE({YES|NO})]
     [△1OPENMFUPDATE]
     [△1COPYPACE({SLOW|NORMAL|FAST})]
   "
}

Parameters specified in the request body

GROUP(copy-group-ID) ~ <GROUP string>

Specify the ID of the target copy groups that are loaded. If only one copy group is loaded, you can omit this parameter.

SELECT({ALL|COND})

Specify the selection method for copy pair to be manipulated by the command. When not specified, ALL is assumed.

ALL

All the copy pairs in the copy group are to be manipulated by the command. Note that if the DEVN parameter is specified, the copy pair specified for the parameter becomes the execution target of the command. If the ORDER parameter is specified, the copy pairs specified for the ORDER parameter become the execution targets of the command.

COND

The pairs to be manipulated by the command depend on their volume status. If all copy pairs within the copy group are either affected by the command or in the target status, processing terminates with return code 0. If copy pairs that are not affected by the command are included in the copy group, processing terminates with return code 4. For more information about copy groups affected by the command and its target status, see the table "Copy pair statuses for which commands with SELECT(COND) specified are subject to processing" in the Hitachi Business Continuity Manager User Guide.

Applies to ShadowImage.

Specify the copy mode.

QUICK

Transit to the DUPLEX status quickly.

NORMAL

Transit to the DUPLEX status after copy completion.

Specify the copy direction.

Based on the information updated since transiting to the SUSPOP status, the differences are copied for tracks and cylinders, and the DUPLEX status is recovered.

When the parameter is not specified in ShadowImage, the differences are copied from P-VOL to S-VOL.

When the parameter is not specified in TrueCopy or Universal Replicator, the differences of the copy pairs in the SUSPOP status are copied.

A copy pair with the S-VOL SWAP status is not copied. The copy direction is not changed after resynchronization.

FORWARD

In ShadowImage, the difference is copied from P-VOL to S-VOL.

In TrueCopy or Universal Replicator, the difference is copied from the Primary site to the Secondary site.

REVERSE

In ShadowImage, the difference is copied from S-VOL to P-VOL.

In TrueCopy or Universal Replicator, the difference is copied from the Secondary site to the Primary site.

Specify the device number of the copy pair (P-VOL and S-VOL) to operate. If you specify this parameter after ATTIME suspend, execute the YKSUSPND command with the CANCEL parameter specified.

VOLUNIT[({LINEAR|DISPERSED})]

When this is specified, operation is performed by volume even when the environment supports operation by group.

Specify the order of operations on volumes in the storage system, by using the LINEAR parameter or the DISPERSED parameter. The default is LINEAR when only the VOLUNIT parameter is specified.

LINEAR

Resynchronizes the volume in the order of the definitions in the copy group definition file. This parameter is usually specified together with the SELECT(COND) parameter when you want to resynchronize (in units of individual volumes) only the copy pairs whose status do not match because of some reason such as an error. If you specify this parameter after ATTIME suspend, execute the YKSUSPND command with the CANCEL parameter specified. If you specify the ORDER parameter, the LINEAR parameter is disabled.

DISPERSED

Applies to Universal Replicator.

Resynchronizes the volume so that the journal group to which the volume belongs is dispersed.

In an environment that meets the following conditions, you can improve performance by dispersing the load on the journal volumes that are being used by executing the YKRESYNC command with the DISPERSED parameter specified.

  • Within a copy group, more than one journal group is defined in the same storage system.

  • Within each journal group, 128 or more copy pairs are defined.

  • The line speed is sufficient.

The following describes the relationship between the VOLUNIT parameter specification and the command execution when issuing the YKRESYNC command to reverse the copy direction.

  • When the VOLUNIT parameter is not specified:

    The command is executed only when the copy pair status is SWAPPING.

  • When the VOLUNIT parameter is specified:

    The command is executed regardless of the copy pair status. However, if the SELECT(COND) parameter is specified at the same time, the command is executed only on the copy pair in the intended status.

    For details about the copy pairs for which operations are to be performed, see the table that describes the statuses of copy pairs subject to processing by the command described in the Hitachi Business Continuity Manager User Guide.

Applies to Universal Replicator.

Perform a Delta Resync. Copy to S-VOL only the journals on the P-VOL side that have a differential with the journals on the S-VOL side. After copying the differential, perform a transition to the DUPLEX status.

Applies to Universal Replicator.

Perform a Delta Resync with full copy to resynchronize delta resync pairs. All the information of the P-VOL is copied to the S-VOL regardless of the differences between the two. After copying has been completed, perform a transition to the DUPLEX status.

When executing the YKRESYNC command with the ALLJNL parameter for a copy group which contains one or more copy pairs in the NODELTA status, perform the following procedure:

  1. Execute the YKRESYNC command with both the ALLJNL parameter and the ERRCHK parameter to make sure the command terminates successfully with the return code 0.

  2. Execute the YKRESYNC command with only the ALLJNL parameter to make sure there all copy pairs can perform full copy.

Applies to Universal Replicator.

Identify the cause of the error that occurred when a delta resync or a delta resync with full copy was executed.

Specify the ERRCHK parameter with either the DELTAJNL parameter or the ALLJNL parameter in the following cases:

  • To make sure Delta Resync (with or without full copy) can be performed correctly before executing the YKRESYNC command with either the DELTAJNL parameter or the ALLJNL parameter.

  • When the copy pair statuses changes to HOLDER status after executing the YKRESYNC command with the DELTAJNL parameter or the ALLJNL parameter.

If the ERRCHK parameter is specified with the YKRESYNC command, no status transition will take place.

If there is a copy pair that cannot perform Delta Resync (with or without full copy), a message (YKZ251E, YKZ253E, YKZ255E, or YKZ257E) is displayed to indicate an error. Remove the cause of the error according to the message, and then re-execute the YKRESYNC command without the ERRCHK parameter.

If the ERRCHK parameter is specified and no abnormal copy pairs exist, the command will terminate normally with the return code 0.

The following table shows an example procedure using the ERRCHK parameter to recover copy pairs that are in an error status.

Table. Example procedure using the ERRCHK parameter after transition to HOLDER status

No.

Command

Description

1

YKQUERY STEM(SF.TO.LA.) MSG(MSG.)

Checks if all copy pairs are in the HOLD status.

2

YKRESYNC STEM(SF.TO.LA.) MSG(MSG.) DELTAJNL SELECT(COND)

Synchronizes delta resync pairs, and checks if the return code is 0.

3

YKEWAIT STEM(SF.TO.LA.) MSG(MSG.) GOTO(DUPLEX) TIMEOUT(5)

Checks the status of all copy pairs if the YKE003E message is output. Use the ERRCHK parameter if there is a copy pair in HOLDER status.

4

YKRESYNC STEM(SF.TO.LA.) MSG(MSG.) DELTAJNL ERRCHK SELECT(COND)

When this command is executed, the message that displays the cause is output, so you need to identify and fix the error.

5

YKRESYNC STEM(SF.TO.LA.) MSG(MSG.) PREPARE SELECT(COND)

Recovers pairs in failure status to HOLD status.

Applies to Universal Replicator.

Restore copy pairs that are in an error status (meaning copy pairs in the HOLDER status, not copy pairs in the SUSPER status) to the HOLD status. Remove the cause of the error in the copy pair that has the HOLDER status, and then specify that pair. If there is no problem, perform a transition to the HOLD status or to the HOLDTRNS status.

When this parameter is specified, commands can be executed whether S-VOL is online or offline (regardless of the specification in the ONLINE parameter).

Specify whether to resynchronize a copy pair if the copy destination volume is online.

YES

The command resynchronizes copy pairs even when the S-VOL (P-VOL if the REVERSE parameter is specified) is online.

NO

The command does not resynchronize copy pairs when the S-VOL (P-VOL if the REVERSE parameter is specified) is online. When the destination volume is online, although an I/O error does not occur in the consistency group, an I/O error message is issued if VOLUNIT parameter is specified. In addition, for Universal Replicator, I/O error might occur in the consistency group.

Applies to TrueCopy.

Specify this parameter to change the Open/MF Consistency attribute (if the Open/MF Consistency Preservation function is used). The Open/MF Consistency attribute of the copy group definition information that is loaded when the command that is executed is applied.

If the command is executed without this parameter specified, the Open/MF Consistency attribute of the copy group definition information that is loaded is not applied. When this parameter is specified, the command is executed in units of volumes, if the environment supports execution in units of groups.

Applies to ShadowImage and TrueCopy.

Specify the copy pace when resynchronizing a copy pair. If this parameter is omitted, the copy pace value specified when the copy group was defined will be used.

SLOW

Slows the speed of the copy operation so that the effect of the copy operation on the I/O performance of the host is minimal.

NORMAL

The speed of the copy operation improves. However, update I/O load on P-VOL is high, and this might affect the I/O performance of the host.

FAST

Applies to ShadowImage.

Specifying FAST speeds up the copy operation so that it is faster than NORMAL. However, specifying FAST adversely affects the I/O performance of the host.

Important:

Specifying COPYPACE(FAST) might adversely affect business operations, so we recommend that you perform such a copy operation outside of business hours.

Notes

  • If operations with a REVERSE specification such as planned outage take place, to control TrueCopy or Universal Replicator from the script, we recommend that you specify the FORWARD or REVERSE parameter explicitly.

  • When specifying the FORWARD or REVERSE parameter to change the copy direction of the copy group, be sure to execute the YKQUERY command or YKEWAIT command and obtain information for the changed copy direction before performing the operation.

  • When a copy is performed from low-capacity TrueCopy or Universal Replicator volumes to high-capacity volumes, if a failure occurs on the secondary site, a TrueCopy or Universal Replicator copy cannot be performed in the reverse direction (from the Secondary site to the Primary site). We recommend strongly that copying from a small volume to a large volume function be used exclusively for data migration.

  • After this command is executed against a volume is SWAPPING status, the direction of copy is reversed.

  • The YKRESYNC command terminates successfully when the instruction to the copy pair succeeds. Even if the YKRESYNC command terminates with return code 0, the copy pair might not be in the DUPLEX status. After you execute the YKRESYNC command, use the YKQUERY or YKEWAIT command to make sure that the copy pair status has changed to DUPLEX. If there is a volume with a status that has not been changed, re-execute the YKRESYNC command with the VOLUNIT parameter specified for all the copy pairs.

  • If ONLINE(YES) parameter is specified, volume corruption might occur because a copy pair can be created even if the S-VOL is being used. Thus, consideration with respect to volume operation is required, such as limiting operation to the time periods when the S-VOL is not being used.

  • To use the YKRESYNC command to reflect the change in the ERRORLEVEL attribute on the device, specify the VOLUNIT parameter (or specify the DEVN parameter on a copy pair basis). If the parameter is not specified, the attribute change is not reflected.

  • Even if the status transition is successful, an I/O error might occur and the command might terminate with return code 32. When you create a script, code it in such a manner that the YKQUERY or YKEWAIT command is executed to check the results of status transitions, even if the command terminates with return code 32, and the processing resumes after a successful status transition.

  • When the COPYPACE(FAST) parameter is specified, if a ShadowImage copy group includes storage system volumes for which FAST is not supported, the copy pairs for which FAST is not supported will be copied by using NORMAL. In addition, if FAST is not supported for any of the storage system volumes in the copy group, the YKZ414E message is output and processing ends.

Return code

If the CLI command has finished running, the return code of the CLI command is set in the rc key of the response. If an error occurs before the CLI command is run, the BCM Web API server sets the return code.

The following table lists and describes the return codes of the YKRESYNC command.

Table. YKRESYNC command return code list

Return code

Meaning

-3

The module cannot be loaded. Possible causes are as follows:

  • The library dataset has not been linked.

  • The module is protected by the RACF program control function.

-1

An interruption occurred during execution.

0

The command completed normally.

4

Since a volume with an invalid status was found in the copy group, processing for the volume will be skipped.

32

  • One or more I/O errors was encountered.

  • A change in an I/O configuration definition was detected.

36

Invalid or missing data in a REXX variable structure.

40

An error occurred while a REXX variable was being written.

44

Termination due to processing errors.

48

The command terminated due to an invalid parameter. Possible reasons include the following.

  • The copy pair corresponding to the device number specified with the DEVN parameter is not found.

  • The YKQUERY or YKEWAIT command was not run immediately before the running of a command specified with the FORWARD/REVERSE parameter.

  • The COPYPACE parameter is specified for Universal Replicator.

  • The COPYPACE(FAST) parameter is specified for a copy type other than ShadowImage.

128

The command terminated abnormally. Possible reasons include the following.

  • The user does not have permission to run the command or use the function.
  • The copy group on which the REVERSE RESYNC protection function is to be used includes a copy pair in the SIMPLEX state.

For details about return codes set by the BCM Web API server, see Return codes set by the BCM Web API server.