Veritas Storage Foundation Intelligent Storage Provisioning 5.0 AdministratorÆs Guide, HP-UX 11i v3, First Edition, May 2008

112 Administering instant snapshots
Creating instant snapshots
Attaching plexes of an instant snapshot
Note: Although this operation is named reattach, the plexes of an ISP snapshot
volume could never have belonged to the parent volume. For this reason, the
description below refers to the attachment, rather than the reattachment, of
snapshot plexes.
This operation is not supported for space-optimized instant snapshots.
See “Reattaching a linked break-off snapshot volume” on page 112.
Using the following command, some or all plexes of an instant snapshot may be
attached to the specified source volume, or to a source volume in the snapshot
hierarchy above the snapshot volume:
# vxsnap [-g diskgroup ] reattach snapvol source= vol \
[nmirror=
number ]
By default, all the plexes are attached, which results in the removal of the
snapshot. If required, the number of plexes to be attached may be specified as
the value assigned to the nmirror attribute.
Note: The snapshot being reattached must not be open to any application. For
example, any file system configured on the snapshot volume must first be
unmounted.
Only the plexes of a snapshot volume that was set up using ISP may be attached.
If the snapshot volume and the source volume lie in different storage pools, the
underlying disks of the snapshot volume are moved to the source volume’s
storage pool. However, if other objects in the snapshot volume’s storage pool are
also configured on these disks, the reattach command fails.
For example the following command attaches one plex from the snapshot
volume, snapmyvol, to the volume, myvol:
# vxsnap -g mydg reattach snapmyvol source=myvol nmirror=1
Reattaching a linked break-off snapshot volume
Unlike other types of snapshot, the reattachment operation for linked break-off
snapshot volumes does not return the plexes of the snapshot volume to the
parent volume. The link relationship is re-established that makes the snapshot
volume a mirror of the parent volume, and this allows the snapshot data to be
resynchronized. However, the snapshot volume is only readopted by its parent
volume if they are both in the same disk group.