VERITAS Storage Foundation 4.1 Oracle Administrator's Guide

Chapter 10, Using Database FlashSnap for Backup and Off-Host Processing
Prerelease 8 September 2005, 8:55am Creating a Snapplan (dbed_vmchecksnap)
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Creating Multi-mirror Snapshots
To make Database Snapshots highly available, the snapped snapshot volume should contain more
than one mirror. This makes the snapshot volumes available even if one of the mirrors gets
disabled. Snapshot volumes can be mounted and the entire database snapshot is usable even if one
of the mirror gets disabled. The multi-mirror snapshots are enabled via
SNAPSHOT_MIRROR=<n> in the snapplan.
Note There are no changes to the Command Line usage or arguments for the Flashsnap tools.
Note Before taking the snapshot, make sure all tagged snapshot mirrors are in SNAPDONE state.
The following sample explains the setup and the procedure for taking multi-mirror snapshots:
1. Add the second mirror and DCO log. When allocating storage for the second mirror and DCO
logs, make sure the snap volumes are splittable. If snap volumes are not splittable,
dbed_vmchecksnap fails with appropriate errors.
Tag the newly added mirror with the same tag as that of the first mirror.
Assume that the volume has fastresync = on, has dcolog = on, and already has one
SNAPDONE mirror and is tagged with dbed_flashsnap.
# vxsnap -g dg_a addmir dg_a_vol1 alloc=dg_a03
# vxedit -g dg_a set putil2=dbed_flashsnap dg_a_vol1-03
2. Add keyword to the snapplan.Here is a sample snapplan.
SNAPSHOT_VERSION=4.0
PRIMARY_HOST=host1
SECONDARY_HOST=host1
PRIMARY_DG=PRODdg
SNAPSHOT_DG=SNAP_PRODdg
ORACLE_SID=PROD
ARCHIVELOG_DEST=/prod_ar
SNAPSHOT_ARCHIVE_LOG=yes
SNAPSHOT_MODE=online
SNAPSHOT_PLAN_FOR=database
SNAPSHOT_PLEX_TAG=dbed_flashsnap
SNAPSHOT_VOL_PREFIX=SNAP_
ALLOW_REVERSE_RESYNC=no
SNAPSHOT_MIRROR=2