Editing OpenVMS (section)

===Clustering===
{{Main|VMScluster}}
OpenVMS supports [[Computer cluster|clustering]] (first called ''VAXcluster'' and later ''VMScluster''), where multiple computers run their own instance of the operating system. Clustered computers (nodes) may be fully independent from each other, or they may share devices like disk drives and printers. Communication across nodes provides a [[single system image]] abstraction.<ref>{{cite web|url=https://vmssoftware.com/docs/VSI_OpenVMS_Cluster_Systems.pdf|title=VSI OpenVMS Cluster Systems|date=August 2019|access-date=January 13, 2021|publisher=VSI}}</ref> Nodes may be connected to each other via a proprietary hardware connection called Cluster Interconnect or via a standard [[Ethernet]] [[local area network|LAN]].

OpenVMS supports up to 96 nodes in a single cluster. It also allows mixed-architecture clusters.<ref name="cluster-docs">{{cite web|url=https://vmssoftware.com/products/clusters/|title=VSI Products - Clusters|website=VSI|access-date=May 4, 2021|archive-date=May 16, 2021|archive-url=https://web.archive.org/web/20210516180900/https://vmssoftware.com/products/clusters/|url-status=dead}}</ref> OpenVMS clusters allow applications to function during planned or unplanned outages.<ref>{{cite web|url=https://www.digiater.nl/openvms/doc/alpha-v8.3/ovms_archived/BUILD_DEPEND_SYS.PDF|title=Building Dependable Systems: The OpenVMS Approach|date=May 1994|publisher=DEC|access-date=July 31, 2021}}</ref> Planned outages include hardware and software upgrades.<ref name="Cluster Uptime"/>