Designing Disaster Recovery Clusters using Metroclusters and Continentalclusters, Reprinted October 2011 (5900-1881)

Figure 74 3DC CAJ/CAJ solution and mirror unit descriptor usage example

Benefits of 3DC DR Solution

The 3DC DR Solution provides the following benefits:

• Maintains data currency

◦ When using 3DC Sync/CAJ solution, synchronous replication over a short distance in a

Metrocluster environment provides the highest level of data currency and application

availability without significant impact to application performance.

• Maintains high performance

◦ When using 3DC CAJ/CAJ solution, asynchronous replication over a long distance in a

Metrocluster environment provides the highest level of data consistency and application

availability without impacting the application performance.

• The 3DC CAJ/CAJ solution can be used even if there is a high network latency and low

network bandwidth between the sites in a Metrocluster. This overcomes the limitations that the

3DC Sync/CAJ solution may have with physical replication links having insufficient bandwidth

to cope with application I/O spikes or that might be susceptible to short periods of

communication outages.

• Allows swift recovery

◦ Metrocluster implementation allows for fast automated failover after a local area disaster.

• Provides a wide area disaster recovery. In case of disaster at one data center, disaster tolerance

is achieved with the remaining two data centers.

• In a Tri-Link configuration, there is no single point of failure for data replication following a

site outage whereas in Bi-Link configuration it is possible to have this under certain scenarios.

• In Bi-Link configuration, there is no need to have replication links among all the 3 sites. This

configuration can be used in scenarios where the replication links does not exist among all

the three sites.

• Allows recovery even when a disaster exceeds regional boundaries or extended duration. A

wide-area disaster could disable both data centers in Metrocluster, but with semi-automatic

Overview of 3DC DR Solution 423