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

Chapter 3, Online Database Backup

Making an Off-Host Backup of an Online Database

Note It is assumed that you have already prepared the volumes containing the file systems for the

datafiles to be backed up as described in “Setting up Volumes for Instant Snapshots” on

page 17. For an Oracle database, it is not necessary to create snapshots of the volumes

containing the file systems for the redo log volumes or archived logs.

If the database is configured on volumes in a cluster-shareable disk group, it is assumed that

the primary host for the database is the master node for the cluster. If the primary host is not

also the master node, all VxVM operations on shared disk groups must be performed on the

master node.

To make an off-host backup of an online database:

1. 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 ready for the backup cycle, and starts tracking

changes to the original volumes. When you are ready to make a backup, proceed to

step 2.

2. 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 to allow recovery from any

backups taken from snapshots, the database must be in LOGRETAIN RECOVERY mode.