Veritas Storage Foundation 5.1 SP1 Advanced Features Administrator"s Guide (5900-1503, April 2011)

Creating and managing full-sized instant snapshots

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 217.

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

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). 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:

# vxsnap -g mydg syncwait snap2myvol

221Administering volume snapshots

Creating instant snapshots