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

321Administering volume snapshots
Creating instant snapshots
■ Reattach some or all of the plexes of the snapshot volume with the original
volume. See “Reattaching an instant snapshot” on page 327 for details.
■ Restore the contents of the original volume from the snapshot volume. You can
choose whether none, a subset, or all of the plexes of the snapshot volume are
returned to the original volume as a result of the operation. See “Restoring a
volume from an instant snapshot” on page 329 for details.
■ Dissociate the snapshot volume entirely from the original volume. This may be
useful if you want to use the copy for other purposes such as testing or report
generation. If desired, you can delete the dissociated volume. See “Dissociating
an instant snapshot” on page 330 for details.
■ If the snapshot is part of a snapshot hierarchy, you can also choose to split this
hierarchy from its parent volumes. See “Splitting an instant snapshot hierarchy”
on page 331 for details.
Creating and managing linked break-off snapshot volumes
Note: Break-off snapshots are suitable for write-intensive volumes, such as database redo
logs.
For linked break-off 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 linked break-off snapshot
1 Use the following command to link the prepared snapshot volume, snapvol, to the
data volume:
# vxsnap [-g diskgroup] [-b] addmir volume mirvol=snapvol \
[mirdg=snapdg]
The optional mirdg attribute can be used to specify the snapshot volume’s current
disk group, snapdg. The
-b option can be used to perform the synchronization in the
background. If the
-b option is not specified, the command does not return until the
link becomes ACTIVE.
For example, the following command links the prepared volume, prepsnap, in the
disk group, mysnapdg, to the volume, vol1, in the disk group, mydg: