A storage area network (SAN) fibre channel arbitrated loop (FCAL) multiple system, multiple resource, storage enclosure and a method are provided for performing enclosure maintenance concurrent with device operations. The storage enclosure includes a plurality of storage resources or storage devices, a plurality of IO adapters (IOAs) coupled to the storage area network and a pair of enclosure services node cards. Each enclosure services node card includes loop connections for the plurality of storage resources. Each enclosure services node card includes a respective global bus connection and a loop connection to each of the plurality of IOAs. Each enclosure services node card is used concurrently by the multiple systems to manage the plurality of storage resources. In the method for performing enclosure maintenance concurrent with device operations, identical maintenance procedures are implemented for the enclosure services node cards and the storage devices. The enclosure services node cards are removable cards and contain active components including port bypass circuits (PBCs). Fibre channel (FC) connections for the plurality of storage resources provide redundant paths to each storage resource and allows access to data on the storage resources to continue when one of the pair of enclosure services node cards fails or is being maintained. Out of band communications to the enclosure services node cards are provided with the global buses, such as I2C buses, rather than FC loop. Multiple IOAs can concurrently use the same enclosure services node card without contention or collision.