About protecting against site failures
Local clustering provides local failover for each site. However, these configurations do not provide protection against large-scale disasters such as major floods, hurricanes, and earthquakes that cause outages for an entire region. The entire cluster can get affected by such an outage. In such situations, global clustering or wide area clustering ensures data availability by migrating applications to the remote clusters that are located considerable distances apart.
Global cluster architecture supports deployment of two or more datacenters, clusters, and subnets that are separated by a larger distance. A global cluster with replicated master server cluster can monitor and manage the replication jobs and clusters at each site. In case of a site outage, it controls the shift of replication roles to the secondary site. It brings up the critical applications and redirects client traffic, from one cluster to the other.
Auto image replication is a NetBackup feature which allows individual disk based backups to be replicated between NetBackup domains. Because the backups are automatically recorded in the NetBackup catalog of the target domain there is not need for catalog replication of complex catalog recovery procedures when using auto image replication. For more information, refer to the NetBackup Administrator's Guide, Volume I.