Data Disaster Recovery

Disaster Recovery

Is the science of returning a system to operating status after a site-wide disaster. DR enables business continuity for significant data center failures for which high availability features cannot cover. Computer systems generally support DR in two ways: backups and replication. Backups entail full or partial copies of data from the master cluster that are stored on separate media. Replication, also known as mirroring, continuously copies data from the master cluster to a geographically remote instance of the system (“replicas” or “mirrors”). For production deployments, mirroring is the preferred strategy for DR. With either method, a copy of the data is available to restore and thus recover from the disaster. Backups involve restoring the saved data into an alternate cluster and enabling that cluster as the new master. DR with mirroring entails activating the mirror, which already has the data loaded, as the new master cluster. (Note that “replication” is also used to refer to the copying of data within a cluster in a data center to eliminate single points of failure and enable high availability.)

In a related area, some systems support point-in-time snapshots, also known as checkpoints, to allow rolling data back to a prior state. This feature is generally used to recover from data corruption due to application or user error. For more information, please see the MapR Snapshots tech brief.