Disaster Tolerance and Recovery in a Serviceguard Cluster

Understanding Types of Disaster Tolerant Clusters

replicate the data between two data centers. HP provides a supported integration toolkit for Oracle 8i Standby DB in the Enterprise Cluster Management Toolkit (ECMT).

RAC is supported by Continentalclusters by integrating it with SGeRAC. In this configuration, multiple nodes in a single cluster can simultaneously access the database (that is, nodes in one data center can access the database). If the site fails, the RAC instances can be recovered at the second site.

Continentalclusters supports a maximum of 4 clusters with up to 16 nodes per cluster (for a maximum of 64 nodes) supporting up to 3 primary clusters and one recovery cluster.

Failover for Continentalclusters is semi-automatic. If a data center fails, the administrator is advised, and is required to take action to bring the application up on the surviving cluster.

Continental Cluster With Cascading Failover

A continental cluster with cascading failover uses three main data centers distributed between a metropolitan cluster, which serves as a primary cluster, and a standard cluster, which serves as a recovery cluster.

Cascading failover means that applications are configured to fail over from one data center to another in the primary cluster and then to a third (recovery) cluster if the entire primary cluster fails. Data replication also follows the cascading model. Data is replicated from the primary disk array to the secondary disk array in the Metrocluster, then replicated to the third disk array in the Serviceguard recovery cluster.

For more information on Cascading Failover configuration, maintenance, and recovery procedures, see the “Cascading Failover in a Continental Cluster” white paper on the high availability documentation web site at http://docs.hp.com -> High Availability -> Continentalcluster.

Comparison of Disaster Tolerant Solutions

Table 1-1summarizes and compares the disaster tolerant solutions that are currently available:

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Chapter 1