Generally, users and applications access a shadow set through
the virtual unit. Occasionally, you may want to change the data
on an individual shadow set member and then pass the changed data
to other shadow set members.
The following series of commands demonstrates how you can
dissolve and recreate the shadow set to perform specialized processes
on one shadow set member and transfer the change to the other shadow
set members.
The following command mounts a shadow set with three shadow
set members:
$ MOUNT DSA9:/SHADOW=($45$DUA2:,$45$DUA4:,$45$DUA8:) MAX1
The following command dissolves the shadow set mounted in
the previous command and makes the individual shadow set members
available:
$ DISMOUNT DSA9:
The following command mounts one former shadow set member
as a disk volume outside of the shadow set:
$ MOUNT/OVERRIDE=SHADOW_MEMBERSHIP $45$DUA2: MAX1
In this command, in order to have write access, you must use
the /OVERRIDE=SHADOW_MEMBERSHIP qualifier to zero the shadow set
generation number. At this point, the disk is mounted as a nonshadowed volume
and can be modified as required.
Before creating a new shadow set, dismount the $45$DUA2 physical
disk, as follows:
$ DISMOUNT/NOUNLOAD $45$DUA2 $ MOUNT DSA9:/SHADOW=$45$DUA2: MAX1
The second command recreates the shadow set with $45$DUA2
as the only member.
Note that mounting $45$DUA2 with the /OVERRIDE=SHADOW_MEMBERSHIP
qualifier automatically zeroed the volume shadowing generation number.
If you were to specify all the former members
of the shadow set in the same command line, the MOUNT command would
consider $45$DUA2 an unrelated volume and would determine that it
requires a copy operation. This would overwrite the earlier modifications.
To save the current contents of $45$DUA2, add the other two
former shadow set members to the new shadow set with a subsequent
MOUNT command:
$ MOUNT DSA9:/SHADOW=($45$DUA4:,$45$DUA8:) MAX1
In this command, $45$DUA4 and $45$DUA8 are added to the shadow
set DSA9. This recreates the original shadow set, except that each
shadow set member now has the benefit of the changed data that was
done to the single shadow set member.