HP Veritas Volume Manager 5.0 -UX 11i v3 manual # vxsnap -g mydg snapwait vol1 nmirror=2

330Administering volume snapshots

Creating instant snapshots

If you specify the -boption to the vxsnap addmir command, you can use the vxsnap snapwait command to wait for synchronization of the snapshot plexes to complete, as shown in this example:

#vxsnap -g mydg snapwait vol1 nmirror=2

2To create a third-mirrorbreak-off snapshot, use the following form of the vxsnap make command.

#vxsnap [-g diskgroup] make source=volume[/newvol=snapvol]\ {/plex=plex1[,plex2,...]/nmirror=number]}

Either of the following attributes may be specified to create the new snapshot volume, snapvol, by breaking off one or more existing plexes in the original volume:

plex Specifies the plexes in the existing volume that are to be broken off. This attribute can only be used with plexes that are in the ACTIVE state.

nmirror Specifies how many plexes are to be broken off. This attribute can only be used with plexes that are in the SNAPDONE state. (Such plexes could have been added to the volume by using the vxsnap addmir command.)

Snapshots that are created from one or more ACTIVE or SNAPDONE plexes in the volume are already synchronized by definition.

For backup purposes, a snapshot volume with one plex should be sufficient. For example, to create the instant snapshot volume, snap2myvol, of the volume, myvol, in the disk group, mydg, from a single existing plex in the volume, use the following command:

#vxsnap -g mydg make source=myvol/newvol=snap2myvol\ /nmirror=1

The next example shows how to create a mirrored snapshot from two existing plexes in the volume:

#vxsnap -g mydg make source=myvol/newvol=snap2myvol\ /plex=myvol-03,myvol-04

3Use fsck (or some utility appropriate for the application running on the volume) to clean the temporary volume’s contents. For example, you can use this command with a VxFS file system:

# fsck -F vxfs /dev/vx/rdsk/diskgroup/snapshot

4If you require a backup of the data in the snapshot, use an appropriate utility or operating system command to copy the contents of the snapshot to tape, or to some other backup medium.

5You now have the following choices of what to do with a third-mirror break- off snapshot:

■Refresh the contents of the snapshot. This creates a new point-in-time image of the original volume ready for another backup. If