Veritas Storage Foundation™ for Oracle 5.0.1 Administrator's Guide

■ You must be logged in as superuser (root).
■ The disk group must be version 110 or later. For more information
on disk group versions, see the vxdg(1M) online manual page.
■ Be sure that a data change object (DCO) and a DCO log volume are
associated with the volume for which you are creating the snapshot.
■ Persistent FastResync must be enabled on the existing database
volumes and disks must be assigned for the snapshot volumes.
FastResync optimizes mirror resynchronization by tracking
updates to stored data that have been missed by a mirror. When
a snapshot mirror is reattached to its primary volumes, only the
updates that were missed need to be re-applied to resynchronize
it. FastResync increases the efficiency of the volume snapshot
mechanism to better support operations such as backup and
decision support. For detailed information about FastResync, see
the Veritas Volume Manager Administrator's Guide.
■ Snapshot mirrors and their associated DCO logs should be on
different disks than the original mirror plexes, and should be
configured correctly for creating snapshots by the system
administrator.
■ When creating a snapshot mirror, create the snapshot on a separate
controller and separate disks from the primary volume.
■ Allocate separate volumes for archive logs.
■ Do not place any datafiles, including control files, in the
$ORACLE_HOME/dbs directory.
Prerequisites
■ Create a separate disk group for Oracle database-related files.
■ Do not share volumes between Oracle database files and other
software.
■ ORACLE_HOME cannot be included in the snapshot mirror.
■ Resynchronization speed varies based on the amount of data
changed in both the primary and snapshot volumes during the
break-off time.
■ Do not share any disks between the original mirror and the
snapshot mirror.
■ Snapshot mirrors for datafiles and archive logs should be created
so that they do not share any disks with the data of the original
volumes. If they are not created in this way, the VxVM disk group
cannot be split and, as a result, Database FlashSnap will not work.
■ In Oracle RAC configurations, use the vxdctl -c mode command
to determine the hostname of the VxVM CVM master node. Prepare
the volume for a snapshot. Snapshot can be taken from a CVM
master or slave node.
Note: Database FlashSnap commands support third-mirror break-off
snapshots only. The snapshot mirror must be in the SNAPDONE state.
Usage notes
233Using Database FlashSnap for backup and off-host processing
Hosts and storage for Database FlashSnap