Full or incremental image copy

When you use the MERGECOPY utility to merge copies, you can choose whether you want to create an incremental image copy or a full image copy. In general, creating a new full image copy is recommended.

Creating a full image copy with MERGECOPY has the following advantages:

  • A new full image copy creates a new recovery point.
  • The additional time that it takes to create a new full image copy does not have any adverse effect on the access to the table space. The only concurrency implication is the access to SYSIBM.SYSCOPY.
  • The range of log records that need to be applied by the RECOVER utility is the same for both the new full image copy and the merged incremental image copy.
  • If the copies are on tape, only one tape drive is required for image copies during recovery.

If you want MERGECOPY to create a new full image copy, specify NEWCOPY YES. The utility inserts an entry for the new full image copy into the SYSIBM.SYSCOPY catalog table.

Otherwise, if you do not specify NEWCOPY or specify NEWCOPY NO, MERGECOPY creates an incremental image copy. The utility deletes all SYSCOPY records of the incremental image copies that have been merged and replaces them with an entry for the new incremental image copy.

Regardless of what you specify for NEWCOPY, if any of the input data sets might not be allocated or you did not specify a temporary work data set (WORKDDN), the utility performs a partial merge.

Recommendation: Use MERGECOPY NEWCOPY YES immediately after each incremental image copy. When you use this option, dates become a valid criterion for deletion of image copy data sets and archive logs. A minimum number of tape drives are allocated for MERGECOPY and RECOVER execution.

If you merge an inline copy with incremental copies, the result is a full inline copy. The data set is logically equivalent to a full image copy, but the data within the data set differs in some respects.