Different Uses for Copy and Minicopy

Prior to the introduction of minicopy, the copy operation was used for two purposes: to add members to a virtual unit, and to restore a member to the shadow set from which it was removed. In order for a member to rejoin the shadow set, its data must be made to match the data on the shadow set.

The copy operation is the principal method for creating a multiple member shadow set. (You can also use the DCL command INITIALIZE/SHADOW to create an empty multi-member shadow set.) The minicopy operation is now the preferred method for returning a member to a shadow set.

Typically, the reason for removing a shadow set member is to back up the data onto tape or disk.

To use a shadow set member to perform a backup operation, a system manager must perform the following steps:

Using the SHOW DEVICE command, verify that the virtual unit is not marked for a merge operation.
Stop the application I/O
The method for doing this is specific to the application and the computing environment.
Remove a shadow set member
Reactivate the application
Back up the data of the shadow set member to disk or tape
While the backup is progressing, the application is writing data to the remaining members of the shadow set.
Return the shadow set member to the shadow set when the backup is complete.




	NOTE: For detailed information about the conditions under which this form of backup is supported, see “Guidelines for Using a Shadow Set Member for Backup”.