Veritas Volume Manager 5.1 SP1 Administrator"s Guide (5900-1506, April 2011)

The size of the plex has several implications:
■ If the new plex is smaller or more sparse than the original plex, an incomplete
copy is made of the data on the original plex. If an incomplete copy is desired,
use the -o force option to vxplex.
■ If the new plex is longer or less sparse than the original plex, the data that
exists on the original plex is copied onto the new plex. Any area that is not on
the original plex, but is represented on the new plex, is filled from other
complete plexes associated with the same volume.
■ If the new plex is longer than the volume itself, then the remaining area of the
new plex above the size of the volume is not initialized and remains unused.
Copying volumes to plexes
This task copies the contents of a volume onto a specified plex. The volume to be
copied must not be enabled. The plex cannot be associated with any other volume.
To copy a plex, use the following command:
# vxplex [-g diskgroup] cp volume new_plex
After the copy task is complete, new_plex is not associated with the specified
volume volume. The plex contains a complete copy of the volume data. The plex
that is being copied should be the same size or larger than the volume. If the plex
being copied is larger than the volume, an incomplete copy of the data results.
For the same reason, new_plex should not be sparse.
Dissociating and removing plexes
When a plex is no longer needed, you can dissociate it from its volume and remove
it as an object from VxVM. You might want to remove a plex for the following
reasons:
■ to provide free disk space
■ to reduce the number of mirrors in a volume so you can increase the length
of another mirror and its associated volume. When the plexes and subdisks
are removed, the resulting space can be added to other volumes
■ to remove a temporary mirror that was created to back up a volume and is no
longer needed
■ to change the layout of a plex
To save the data on a plex to be removed, the configuration of that plex must be
known. Parameters from that configuration (stripe unit size and subdisk ordering)
291Creating and administering subdisks and plexes
Copying volumes to plexes