What Is Disaster Tolerance?

Disaster tolerance is the ability of a system to restore an application on an alternate cluster when the primary cluster fails. Disaster tolerance is based on data replication and failover.

Data replication is the copying of data from a primary cluster to a backup or secondary cluster. Through data replication, the secondary cluster has an up-to-date copy of the data on the primary cluster. The secondary cluster can be located far away from the primary cluster.

Failover is the automatic relocation of a resource group or device group from a primary cluster to a secondary cluster. If the primary cluster fails, the application and the data are immediately available on the secondary cluster.