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
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:
$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.