VERITAS FlashSnap Point-In-Time-Copy Solutions Administrator's Guide

Creating an Off-Host Replica Database
54 VERITAS FlashSnap Point-In-Time Copy Solutions Administrator’s Guide
Note It is assumed that you have already prepared the database volumes to be replicated as
described in “Setting up Volumes for Instant Snapshots” on page 17.
To set up a replica database to be used for decision support on an OHP host:
1. If you have not already done so, prepare the OHP host to use the snapshot volume that contains
the copy of the database tables. Set up any new database logs and configuration files that are
required to initialize the database. See “Preparing a Replica Oracle Database” on page 81 for
details of this procedure for an Oracle database.
2. On the primary host, use the following command to make a full-sized snapshot, snapvol, of the
tablespace volume by breaking off plexes from the original volume:
# vxsnap -g volumedg make \
source=volume/newvol=snapvol/nmirror=N
The nmirror attribute specifies the number of mirrors, N, in the snapshot volume.
If the volume does not have any available plexes, or its layout does not support plex break-off,
use the procedure described in “Creating a Volume for Use as a Full-Sized Instant Snapshot”
on page 23 to prepare an empty volume for the snapshot, and then use the following command
to create the snapshot:
# vxsnap -g volumedg make source=volume/snapvol=snapvol
If a database spans more than one volume, specify all the volumes and their snapshot volumes
as separate tuples on the same line, for example:
# vxsnap -g dbasedg make source=vol1/newvol=svol1 \
source=vol2/newvol=svol2 source=vol3/newvol=svol3
Note This step sets up the snapshot volumes, and starts tracking changes to the original
volumes. When you are ready to create the replica database, proceed to step 3.
3. If the volumes to be backed up contain database tables in file systems, suspend updates to the
volumes:
◆ DB2 provides the write suspend command to temporarily suspend I/O activity for a
database. As the DB2 database administrator, use a script such as that shown in “Script to
Suspend I/O for a DB2 Database” on page 71. Note that if the replica database must be
able to be rolled forward (for example, if it is to be used as a standby database), the
primary database must be in LOGRETAIN RECOVERY mode.
◆ Oracle supports online backup by temporarily suspending updates to the datafiles of the
tablespaces, provided that the database is running in archive mode and the tablespaces are
online. As the Oracle database administrator, put each tablespace into hot backup mode
using a script such as that shown in “Script to Put Oracle Database into Hot Backup
Mode” on page 69.