A '''distributed lock manager''' (DLM) provides [[distributed programming|distributed]] [[software application]]s with a means to synchronize their accesses to [[shared resource]]s.
DLMs have been used as the foundation for several successful [[clustered file systesystem]]mss, in which the machines in a [[computer cluster|cluster]] can use each other's storage via a unified [[file system]], with significant advantages for performance and [[high-availability|availability]]. The main performance benefit comes from solving the problem of [[cache coherency|disk cache coherency]] between participating computers. The DLM is used not only for [[file locking]] but also for coordination of all [[disk (storage device)|disk]] access. [[VMScluster]], the first clustering system to come into widespread use, relies on the [[OpenVMS]] DLM in just this way.
