User`s guide

4. The extraction of the snapshot member is done with the REDUCE command.
The copy must be done before the REDUCE will be honored. If multiple
snapshot members are involved (as they will be if you are copying the data
on a stripeset or striped mirrorset), then all copies on all members must be
complete.
5. Snapshot disks must be the same size or larger than the disk members they
will be used to copy.
6. The snapshot unit will be an identical copy of the original, right down to
volume labels and file system information that is normally unique. If you
wish to access the snapshot copy on the same system as the original while the
original is still active, you need to take the appropriate steps to override the
host system’s usual protections against such duplication.
7. Any unit created by CLONE has a mirrorset level in the configuration
heirarchy, even if the original unit did ot have mirroring. The target disk of
a single disk unit is mirrored then added and initialized by CLONE. Because
the target disk is initialized as a mirrorset member, CLONE makes it into a
single-member mirrorset to preserve the metadata before adding it as a unit.
8. The CLONE utility is a handy means of automating snapshot copies if you
don’t want to manage the details yourself (see Section 7.3.12).
6.10 Steps for Creating a Mirrorset
This section describes the steps neccessary to capture a snapshot copy of the data
on a single disk container. These steps can be accomplished automatically by the
CLONE utility. Following are the specific steps to making a snapshot copy using
the HS mirroring facility:
1. Identify the unit to be copied.
2. Use SHOW commands to determine the individual disk devices that make up
the unit and their sizes.
CLI> SHOW DEVICES
CLI> SHOW STORAGESETS FULL
3. Identify the unused disks that you will use as the snapshot targets.
4. If the unit is a simple disk or simple stripeset unit, use the MIRROR
command to convert each disk in the unit to a one-member mirrorset. If the
unit is already layered on a mirrorset or striped mirrorset, this step is not
necessary. If the unit being snapshot is a simple stripeset, you will create a
distinct mirrorset for each member.
CLI> MIRROR disk-device-name container-name
5. The unit should now be layered entirely on mirrorsets. Use SHOW commands
to satisfy yourself that this is the case.
6. For each mirrorset in the unit, set the replacement policy to NOPOLICY. This
will provide more precise control over which snapshot targets are used for
each disk.
CLI> SET mirrorset-container-name NOPOLICY
6–20 Working with RAID Arrays