Database image copy 2 (DFSUDMT0)

The Database Image Copy 2 utility (DFSUDMT0) uses either the DFSMSdss concurrent copy function or the DFSMSdss fast replication function to take an image copy.

When using the concurrent copy option, DFSUDMT0 invokes DFSMSdss to dump the input data set. The output is recorded in the RECON data set and can be used for database recovery in the same way as the output from either of the other image copy utilities. You can use this utility for HISAM, HIDAM, HDAM, PHDAM, PHIDAM, and PSINDEX databases and for DEDB areas. Database data sets that are to be copied by this utility must reside on hardware that supports the Concurrent Copy option.

An optional COMPRESS parameter invokes the compress option in DFSMSdss concurrent copy. The compress option enables you to reduce the storage space required to hold the image copy; however, using the compress option increases the CPU time that is required to perform the copy operation.

To lower CPU usage and improve compression, the DFSUDMT0 requests compression from DFSMDdss with the COMPRESS ZCOMPRESS(PREFERRED) options, so that if z/Enterprise Data Compression (zEDC) services are enabled in your z/OS system, zEDC is used for compression. If zEDC is not enabled, or if the request for zEDC services is rejected for any reason, the standard DFSMSdss compression routines are used.

Note: The COMPRESS parameter is not available to DFSMSdss fast replication.

When using the fast replication option, DFSUDMT0 invokes DFSMSdss to COPY the input data set. The output is recorded in the RECON data set and can be used for database recovery in the same way as the output from either of the other image copy utilities. You can use this utility for HISAM, HIDAM, HDAM, PHDAM, PHIDAM, and PSINDEX databases and for DEDB areas. Database data sets that are to be copied by this utility must reside on hardware that supports the fast replication option.

The Database Image Copy 2 utility provides greater database availability when taking consistent image copies. The database needs to unavailable for update processing for only a very short period of time while DFSMSdss establishes a concurrent copy or fast replication session. Update processing can then be resumed while the image copy data sets are actually being written. The updates are not included in the image copy.

This utility can also copy the database while it is being updated by IMS applications. The image copy created in this case is a fuzzy image copy. The Database Image Copy 2 utility can copy all supported data set types, including VSAM KSDSs, while the databases remain online. In order to copy a VSAM KSDS while it is online, it must be SMS managed and allocated with IDCAMS using the BWO(TYPEIMS) parameter.

Requirement: The Database Image Copy 2 utility must use DBRC and the databases and areas being copied must be registered with DBRC. The utility can create up to 4 copies using concurrent copy; only 1 copy can be made using fast replication. Only the information about the primary and secondary copies are recorded in the RECON data set.

The concurrent copy image copy output from the Database Image Copy 2 utility is in DFSMSdss dump format, which is different than the format of the output of the other image copy utilities. It is, however, directly usable as input to database recovery. Information about the image copies are recorded in the RECON data set with image copy type SMSCIC, or SMSNOCIC.

The image copy output from a fast replication invocation of the Database Image Copy 2 utility is in DFSMSdss copy format, which is different than the format of the output of the other image copy utilities. Like the DFSMSdss dump format, it is directly usable as input to database recovery. Information about the image copies are recorded in the RECON data set with image copy type SMSONLC or SMSOFFLC.

Requirement: The Database Recovery utility must use DBRC when using the SMSCIC, SMSNOCIC, SMSONLC, or SMSOFFLC image copy data sets for recovery.