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

Implementing Off-Host Point-In-Time Copy Solutions
12 VERITAS FlashSnap Point-In-Time Copy Solutions Administrator’s Guide
Implementing Off-Host Point-In-Time Copy Solutions
As shown in “Example Implementation of an Off-Host Point-In-Time Copy Solution” on page 12,
by accessing snapshot volumes from a lightly loaded host (shown here as the OHP host), CPU- and
I/O-intensive operations for online backup and decision support are prevented from degrading the
performance of the primary host that is performing the main production activity (such as running a
database). Also, if you place the snapshot volumes on disks that are attached to host controllers
other than those for the disks in the primary volumes, it is possible to avoid contending with the
primary host for I/O resources. To implement this, paths 1 and 2 shown in the following figures
should be connected to different controllers.
Example Implementation of an Off-Host Point-In-Time Copy Solution
The figure “Example Connectivity for Off-Host Solution Using Redundant-Loop Access” on
page 13 gives an example of how you might achieve such connectivity using Fibre Channel
technology with 4 Fibre Channel controllers in the primary host. This layout uses redundant-loop
access to deal with the potential failure of any single component in the path between a system and a
disk array.
Note On some operating systems, controller names may differ from what is shown here.
Network
Disks containing primary
volumes used to hold
production databases or file
systems
Disks containing snapshot
volumes
SCSI or Fibre
Channel Connectivity
OHP Host
Primary Host
12