Veritas Volume Manager 5.1 SP1 Administrator"s Guide (5900-1506, April 2011)

Logic errors caused by an administrator or an application program
can compromise the integrity of a database. By restoring the database
table files from a snapshot copy, the database can be recovered more
quickly than by full restoration from tape or other backup media.
Database error
recovery
Using linked break-off snapshots makes off-host processing simpler.
For more information about snapshots, see the Veritas Storage Foundation
Advanced Features Administrator's Guide.
Implemention of off-host processing solutions
Figure 11-1 shows an example implementation of off-host processing.
Figure 11-1
Example implementation of off-host processing
Disks containing
primary volumes
used to hold
production
databases or systems
Disks containing
snapshot volumes
used to implement
off-host processing
solutions
Primary host
SCSI or Fibre
Channel
connectivity
OHP host
By accessing snapshot volumes from a lightly-loaded host (shown here as the
off-host processing (OHP) host), CPU- and I/O-intensive operations for online
backup and decision support do not degrade the performance of the primary host
that is performing the main production activity (such as running a database). If
you also place the snapshot volumes on disks that are attached to different host
controllers than the disks in the primary volumes, it is possible to avoid contending
with the primary host for I/O resources.
The following sections describe how you can apply off-host processing to
implement regular online backup of a volume in a private disk group, and to set
up a replica of a production database for decision support. The following
applications are outlined:
See “Implementing off-host online backup” on page 395.
Configuring off-host processing
Implemention of off-host processing solutions
394