Device Locks: mutual exclusion for storage area networks
Kenneth W. Preslan, S.R. Soltis, C.J. Sabol, Matthew T. O'Keefe, Gerry Houlder, Jim Coomes · 2003
Device Locks are mechanisms used in distributed environments to facilitate mutual exclusion of shared resources. They can further be used to maintain coherence of data that is cached in several locations. The locks are implemented on the storage devices and accessed with the SCSI device lock command, Dlock. The paper presents the Dlock command and discusses how it can be used as a mutual exclusion device for storage area networks and shared disk file systems. Methods for the recovery of a Dlock held by a failed initiator are also presented. The Dlock command is in the process of being standardized as part of the SCSI 3 specification.