Distributed lock manager: Difference between revisions

Revision as of 15:00, 10 June 2021

Revision as of 04:33, 6 July 2021

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[[Operating system]]s use lock managers to organise and serialise the access to resources. A '''distributed lock manager''' (DLM) runs in every machine in a cluster, with an identical copy of a cluster-wide lock database. In this way a DLM provides [[software application]]s which are [[distributed programming|distributed]] across a cluster on multiple machines with a means to synchronize their accesses to [[shared resource]]s.

DLMs have been used as the foundation for several successful [[clustered file system]]s, 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, reliesrelied on the [[OpenVMS]] DLM in just this way.

==VMS implementation==

[[Digital Equipment Corporation|DEC]]'s [[OpenVMS|VMS]] (virtual memory system) was the first widely available operating system to implement a DLM. This became available in Version 4, although the user interface was the same as the single-processor lock manager that was first implemented in Version 3.

===Resources===