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

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Setting up Volumes for Instant Snapshots
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This chapter describes how to make volumes ready for instant snapshot creation. These may be
volumes that you want to back up, or that you want to use for decision support or reporting.
If a snapshot volume is to be used on the same host, and will not be moved to another host for
off-host processing, you can use space-optimized instant snapshots rather than full-sized instant
snapshots. Depending on the application, space-optimized snapshots typically require 10% of the
disk space that is required for full-sized instant snapshots.
For more information about administering instant snapshots and FastResync, see the VERITAS
Volume Manager Administrator’s Guide.
The following table summarizes which volumes require the creation of snapshot mirrors for
backup, decision support, and database error recovery.
Caution To avoid data inconsistencies, do not use the same snapshot with different point-in-time
copy applications. If you require snapshot mirrors for more than one application,
configure at least one snapshot mirror that is dedicated to each application.
If the existing volume was created before release 4.0 of VxVM, and it has any attached snapshot
plexes, is associated with any snapshot volumes, or has any dedicated DRL logs, follow the
procedure given in the section “Upgrading Existing Volumes to Use Version 20 DCOs” in the
“Administering Volumes” chapter of the VERITAS Volume Manager Administrator’s Guide. The
procedure given in this section assumes that no snapshot plexes, snapshot volumes, or DRL logs
are associated with the volumes.
Creation of Snapshot Mirrors
Point-In-Time Copy Application Create Snapshot Mirrors for Volumes containing...
Online Database Backup
VxFS file systems for database datafiles to be backed up.
Off-Host Cluster File System
Backup
VxFS cluster file systems to be backed up.
Decision Support
VxFS file systems for database datafiles to be replicated.