Recovery groups

A recovery group is the fundamental organizing structure employed by IBM Storage Scale RAID. A recovery group is conceptually the internal GPFS equivalent of a hardware disk controller. Within a recovery group, individual JBOD disks are defined as pdisks and assigned to declustered arrays. Each pdisk belongs to exactly one declustered array within one recovery group. Within a declustered array of pdisks, vdisks are defined. The vdisks are the equivalent of the RAID logical unit numbers (LUNs) for a hardware disk controller. One or two GPFS cluster nodes must be defined as the servers for a recovery group, and these servers must have direct hardware connections to the JBOD disks in the recovery group. Two servers are recommended for high availability server failover, but only one server will actively manage the recovery group at any given time. One server is the preferred and primary server, and the other server, if defined, is the backup server.

Multiple recovery groups can be defined, and a GPFS cluster node can be the primary or backup server for more than one recovery group. The name of a recovery group must be unique within a GPFS cluster.