VERITAS Storage Foundation 4.1 Oracle Administrator's Guide

Preparing Hosts and Storage for Database FlashSnap Prerelease 8 September 2005, 8:55am
206 VERITAS Storage Foundation for Oracle 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.
Usage Notes
◆ 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.
Note Database FlashSnap commands support third-mirror break-off snapshots only. The snapshot
mirror must be in the SNAPDONE state.
Caution The procedure given in this section is for existing volumes without existing snapshot
plexes or associated snapshot volumes.
▼ To create a snapshot mirror of a volume or volume set
Note In the following procedure, volume_name is the name of either a volume or a volume set.
1. To prepare the volume for being snapshot, use the vxsnap prepare command:
# vxsnap -g diskgroup prepare volume \
alloc="storage_attribute ..."
Note The vxsnap prepare command automatically creates a DCO and DCO volumes and
associates them with the volume, and enables Persistent FastResync on the volume.
Persistent FastResync is also set automatically on any snapshots that are generated from a
volume on which this feature is enabled.