Designating FlashCopy usage

The FASTREPLICATION(REQUIRED | PREFERRED | NONE) keyword tells DFSMSdss how you want to use fast replication methods such as FlashCopy®. The default is FASTREPLICATION(PREFERRED).

FASTREPLICATION(REQUIRED) specifies that DFSMSdss must use data set FlashCopy for the DEFRAG operation. If FlashCopy cannot be used for one of the following normal reasons, DFSMSdss issues informational message ADR946I and error message ADR938E, which indicates that the processing of the current extent failed. DEFRAG processing attempts to use FlashCopy to move the subsequent extents.

The target tracks are already the source of a FlashCopy operation.
The source tracks are already the target of a FlashCopy operation.
The target tracks will exceed 12 relationships, which is the maximum relationships that are allowed for any source tracks.

If FlashCopy cannot be used for reasons other than the normal reasons, DFSMSdss issues message ADR945W and error message ADR938E, which indicates that the processing of the current extent failed. DFSMSdss terminates DEFRAG processing.

FASTREPLICATION(PREFERRED) specifies that DFSMSdss attempt to use data set FlashCopy before any other I/O method. If data set FlashCopy cannot be used for one of the normal reasons listed earlier, DFSMSdss issues message ADR946I and uses traditional I/O methods to move the current extent. DEFRAG processing attempts to use FlashCopy to move the subsequent extents. If FlashCopy cannot be used for reasons other than the normal reasons, DFSMSdss issues message ADR945W and uses traditional I/O methods to move the current extent and all the subsequent extents on the volume.

NOTE: The unexpected FlashCopy failures are logged in the LOGREC by services that DFSMSdss initiates to perform a FlashCopy operation. The normal FlashCopy reasons are not logged in the LOGREC.

FASTREPLICATION(NONE) specifies that DFSMSdss not attempt to use data set FlashCopy during the DEFRAG operation.

For more information about the FASTREPLICATION(REQUIRED | PREFERRED | NONE) keyword, refer to z/OS DFSMSdfp Storage Administration.