Disaster Tolerance and Recovery in a Serviceguard Cluster

Understanding Types of Disaster Tolerant Clusters

Benefits of Continentalclusters

•You can virtually build data centers anywhere and still have the data centers provide disaster tolerance for each other. Since Continentalclusters uses two clusters, theoretically there is no limit to the distance between the two clusters. The distance between the clusters is dictated by the required rate of data replication to the remote site, level of data currency, and the quality of networking links between the two data centers.

•In addition, inter-cluster communication can be implemented with either a WAN or LAN topology. LAN support is advantageous when you have data centers in close proximity to each other, but do not want the data centers configured into a single cluster. One example may be when you already have two Serviceguard clusters close to each other and, for business reasons, you cannot merge these two clusters into a single cluster. If you are concerned with one of the centers becoming unavailable, Continentalclusters can be added to provide disaster tolerance. Furthermore, Continentalclusters can be implemented with an existing Serviceguard cluster architecture while keeping both clusters running, and provide flexibility by supporting disaster recovery failover between two clusters that are on the same subnet or on different subnets.

•You can integrate Continentalclusters with any storage component of choice that is supported by Serviceguard. Continentalclusters provides a structure to work with any type of data replication mechanism. A set of guidelines for integrating other data replication schemes with Continentalclusters is included in the Designing Disaster Tolerant HA Clusters Using Metrocluster and Continentalclusters user’s guide.

•Besides selecting your own storage and data replication solution, you can also take advantage of the following HP pre-integrated solutions:

—Storage subsystems implemented by CLX are also pre-integrated with Continentalclusters. Continentalclusters uses the same data replication integration module that CLX implements to check for data status of the application package before package start up.

—If Oracle DBMS is used and logical data replication is the preferred method, depending on the version, either Oracle 8i Standby or Oracle 9i Data Guard with log shipping is used to

Chapter 1

29