Veritas Volume Manager 5.0 Administrator's Guide (September 2006)

317Administering volume snapshots
Creating instant snapshots
snapshot having to be resynchronized. See “Refreshing an instant snapshot” on
page 327 for details.
■ Restore the contents of the original volume from the snapshot volume. The
space-optimized instant snapshot remains intact at the end of the operation. See
“Restoring a volume from an instant snapshot” on page 329 for details.
Creating and managing full-sized instant snapshots
Note: Full-sized instant snapshots are not suitable for write-intensive volumes (such as for
database redo logs) because the copy-on-write mechanism may degrade the performance
of the volume.
For full-sized instant snapshots, you must prepare a volume that is to be used as the
snapshot volume. This must be the same size as the volume for which the snapshot is
being created, and it must also have the same region size. See “Creating a volume for use
as a full-sized instant or linked break-off snapshot” on page 314 for details.
The attributes for a snapshot are specified as a tuple to the
vxsnap make command. This
command accepts multiple tuples. One tuple is required for each snapshot that is being
created. Each element of a tuple is separated from the next by a slash character (/). Tuples
are separated by white space.
To create and manage a full-sized instant snapshot
1 To create a full-sized instant snapshot, use the following form of the
vxsnap make
command:
# vxsnap [-g diskgroup] make source=volume/snapvol=snapvol\
[/snapdg=snapdiskgroup] [/syncing=off]
The command specifies the volume, snapvol, that you prepared earlier.
For example, to use the prepared volume, snap1myvol, as the snapshot for the
volume, myvol, in the disk group, mydg, use the following command:
# vxsnap -g mydg make source=myvol/snapvol=snap1myvol
For full-sized instant snapshots that are created from an empty volume, background
synchronization is enabled by default (equivalent to specifying the
syncing=on
attribute). If you want to move a snapshot into a separate disk group, or to turn it into
an independent volume, you must wait for its contents to be synchronized with those
of its parent volume.
You can use the
vxsnap syncwait command to wait for the synchronization of the
snapshot volume to be completed, as shown here:
# vxsnap [-g diskgroup] syncwait snapvol
For example, you would use the following command to wait for synchronization to
finish on the snapshot volume, snap2myvol: