Veritas Storage Foundation Intelligent Storage Provisioning 5.0.1 Administrators Guide, HP-UX 11i v3, First Edition, November 2009

To prepare a volume for the creation of instant and break-off snapshots

Use the following commands to see if the volume is associated with a version

20 data change object (DCO) and DCO volume that allow instant snapshots

and Persistent FastResync to be used with the volume, and to check that

FastResync is enabled on the volume:

# vxprint -g volumedg -F%instant volume

# vxprint -g volumedg -F%fastresync volume

If both commands return a value of on, the volume can be used for instant

snapshot operations, and you should skip to step 3.

Otherwise continue with step 2.

To prepare a volume for instant snapshots, use the following command:

# vxsnap [-g diskgroup] prepare volume [regionsize=size] \

[ndcomirs=number] [alloc=storage_attributes]

For example, to prepare the volume, myvol, in the disk group, mydg, use the

following command:

# vxsnap -g mydg prepare myvol regionsize=128k ndcomirs=2 \

alloc=mydg10,mydg11

This example creates a DCO object and redundant DCO volume with two

plexes located on disks mydg10 and mydg11, and associates them with myvol.

The region size is also increased to 128KB from the default size of 64KB. The

region size must be a power of 2, and be greater than or equal to 16KB. A

smaller value requires more disk space for the change maps, but the finer

granularity provides faster resynchronization.

109Administering instant snapshots

Creating instant snapshots