A storage virtualization system for accessing at least one storage device
for a virtual logical unit (VLUN) from at least one host. The system
includes at least one upstream processing element (UPE) which is adapted
for coupling to a corresponding host server. The system is further
adapted for coupling to at least one storage device. The controller also
includes a primary central processing element (CPE) that can be
configurably coupled to the UPEs. The primary CPE permits data transfer
to occur between a host and a storage device via the corresponding UPE.
The controller further includes a backup CPE that can be configurably
coupled to the UPEs. The backup CPE is configurable to permit the data
transfer when the primary CPE becomes unavailable.