Building Disaster Recovery Serviceguard Solutions Using Metrocluster with Continuous Access for P9000 and XP A.11.00

Delta Resync Pair

The Delta Resync pair must be configured when using 3DC Tri-Link configuration. The Delta Resync

pair must be created with the –nocsus option to the paircreate command. The –nocsus

option creates a suspended journal volume, without copying the data. Figure 32 (page 96) shows

an example 3DC Sync/CAJ replication using Delta Resync pair configured between Site2 and

Site3.

Figure 32 Delta Resync Configuration

Site 1

CA-jnl

CA-Sync

Site 2

Site 3

S-VOL

Jnl

Vol

Jnl

Vol

P-VOL

Jnl

Vol

CA-Jnl Delta Resync

In a 3DC replication configured with Delta Resync functionality, data is replicated to the third site

from one of the sites in the Metrocluster; a Delta Resync pair is configured from the other site. In

the event of failure of the site from which data is being copied to the third site, the Delta Resync

pair can be used. To replicate data to the third site over Delta Resync pair, run the pairresync

command on the Delta Resync pair. This copies only the delta changes providing faster

re-synchronization of the data.

For more information on Delta Resync pair, see HP StorageWorks P9000 Continuous Access

Journal Software User Guide or HP StorageWorks XP24000/XP20000 Continuous Access Journal

Software User Guide available at http://h20000.www2.hp.com/bizsupport/TechSupport/

Home.jsp.

Remote Command Device

The Remote Command Device (RCMD) feature allows the storage administrator to present the

command device from one array to another remote array via the P9000 or XP External Storage

functionality. In case of 3DC Tri-Link configuration using Delta Resync, remote command devices

must be created on each P9000 or XP array for the other two P9000 or XP arrays. In 3DC

replication with Delta Resync, it is required to assign a remote command device to the mirrors in

each site. Figure 33 (page 97) shows the Configuration of the Delta resync operation that utilizes

RCMD. To configure Remote Command Devices, see section Configuring Delta Resync Operation

Environment that uses Remote Command Devices in the document HP StorageWorks P9000

96 Designing a Three Data Center Disaster Recovery Solution