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 Preparing Hosts and Storage for Database FlashSnap
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◆ The same version of Oracle is installed on both hosts the Oracle binaries and datafiles are on
different volumes and disks.
◆ The UNIX login for the database user and group must be the same on both hosts.
◆ You have a VERITAS Storage Foundation 4.1 for Oracle Enterprise Edition license on both
hosts.
Creating a Snapshot Mirror of a Volume or Volume Set Used by the
Database
With Database FlashSnap, you can mirror the volumes used by the database to a separate set of
disks, and those mirrors can be used to create a snapshot of the database. These snapshot volumes
can be split and placed in a separate disk group. This snapshot disk group can be imported on a
separate host, which shares the same storage with the primary host. The snapshot volumes can be
resynchronized periodically with the primary volumes to get recent changes of the datafiles. If the
primary datafiles become corrupted, you can quickly restore them from the snapshot volumes.
Snapshot volumes can be used for a variety of purposes, including backup and recovery, and
creating a clone database.
You must create snapshot mirrors for all of the volumes used by the database datafiles before you
can create a snapshot of the database. This section describes the procedure used to create snapshot
mirrors of volumes.
You can use the vxsnap CLI command or the GUI to create a snapshot mirror. Creating a
snapshot mirror using the GUI is relatively easy. Because the time required to synchronize a
snapshot mirror can be long, using the command line is recommended when resynchronizing
snapshot mirrors.
Prerequisites
◆ 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.