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.
