Figure 63 3DC DR Solution Configuration

The 3DC DR Solution consists of three sites: Site1, Site2 and Site3 as shown in Figure 63 (page 414). There is a P9000 or XP array at each site and they are connected to each other using Continuous Access links. The nodes and the two XP arrays at Site1 and Site2 are configured as a Metrocluster. At Site3, an independent Serviceguard cluster is configured and connected to a third P9000 or XP disk array. A Continentalclusters is configured with the Metrocluster at Site1 and Site2, as the primary cluster and the independent cluster at Site3 as the recovery cluster.

Overview of Continuous Access 3DC Replication Technology

The Continuos Access 3DC replication can be configured using either 3DC Sync/CAJ replication or 3DC CAJ/CAJ replication. Here CAJ refers to Continuous Access Journal. In 3DC Sync/CAJ replication, the replication between the sites located in Metrocluster is synchronous and configured using Continuous Access Synchronous device group pair where as in 3DC CAJ/CAJ replication, the replication between the sites located in Metrocluster is asynchronous and configured using Continuous Access Journal replication device group pair. For information regarding CAJ, 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.

Table 31 Difference Between 3DC Sync/CAJ and 3DC CAJ/CAJ Replication

3DC Sync/CAJ replication

3DC CAJ/CAJ replication

 

 

The replication between the sites in a Metrocluster is

The replication between the sites in a Metrocluster is

synchronous.

asynchronous using Continous Access Journal replication

 

available in StorageWorks XP and P9000 Storage Arrays.

 

 

Highest level of data currency is maintained at the other

Data may be lagging at the other site in the Metrocluster.

site in the Metrocluster.

 

 

 

Performance of the application may be impacted due to

Performance of the application is not impacted due to the

the synchronous replication between the sites in the

replication between the sites in the Metrocluster.

Metrocluster. This depends on workload, intersite link

 

bandwidth provisioned and read/write ratio amongst other

 

factors.

 

 

 

414 Designing a Three Data Center Disaster Recovery Solution