HP OpenVMS Systems Documentation

Content starts here Modifying Data on Individual Shadow Set Members
HP Volume Shadowing for OpenVMS: OpenVMS Version 8.4 > Chapter 9 Performing System Management Tasks on Shadowed Systems

Modifying Data on Individual Shadow Set Members

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:


The following command mounts one former shadow set member as a disk volume outside of the shadow set:


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:


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.