336Administering volume snapshots

Creating instant snapshots

Adding snapshot mirrors to a volume

If you are going to create a full-sized break-off snapshot volume, you can use the following command to add new snapshot mirrors to a volume:

#vxsnap [-b] [-g diskgroup] addmir volumevolume_set \ [nmirror=N] [alloc=storage_attributes]

Note: The volume must have been prepared using the vxsnap prepare command as described in “Preparing a volume for DRL and instant snapshots” on

page 275.

If a volume set name is specified instead of a volume, the specified number of plexes is added to each volume in the volume set.

By default, the vxsnap addmir command adds one snapshot mirror to a volume unless you use the nmirror attribute to specify a different number of mirrors. The mirrors remain in the SNAPATT state until they are fully synchronized. The -boption can be used to perform the synchronization in the background. Once synchronized, the mirrors are placed in the SNAPDONE state.

For example, the following command adds 2 mirrors to the volume, vol1, on disks mydg10 and mydg11:

#vxsnap -g mydg addmir vol1 nmirror=2 alloc=mydg10,mydg11

Note: This command is similar in usage to the vxassist snapstart command, and supports the traditional third-mirror break-off snapshot model. As such, it does not provide an instant snapshot capability.

Once you have added one or more snapshot mirrors to a volume, you can use the vxsnap make command with either the nmirror attribute or the plex attribute to create the snapshot volumes.

Removing a snapshot mirrorTo remove a single snapshot mirror from a volume, use this command:#vxsnap [-gdiskgroup] rmmir volumevolume_set

For example, the following command removes a snapshot mirror from the volume, vol1:

# vxsnap -g mydg rmmir vol1