About protecting against SAN connection failures
SAN connections generally exist between the backup servers and the backup storage; although the NetBackup SAN client also supports SAN connections from clients to media servers. In all cases, to protect NetBackup against SAN connection failure, SANs should be configured to provide redundant connections between the source and the target components.
Most SAN-attached disk arrays have redundant SAN connections and support dynamic multi-pathing (DMP) software. This redundancy ensures that the connection to the storage is maintained even if one path fails. In many cases, DMP software also load balances traffic across SAN connections to improve the data transfer rates to and from the disk storage.
Many SAN-attached tape devices also offer two connections for redundancy, and thus they appear to servers as two separate devices. Multi-path selection is not dynamic. NetBackup selects the first available path it finds and always uses that path. The second device path is only used if the first path is broken.