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VOTEQUORUM_OVERVIECorosync Cluster Engine Programmer's MVOTEQUORUM_OVERVIEW(8)

NAME
       votequorum_overview - Votequorum	Library	Overview

OVERVIEW
       The  votequorum	library	 is delivered with the corosync	project. It is
       the external interface to the vote-based	quorum service.	 This  service
       is  optionally  loaded  into  all  nodes	in a corosync cluster to avoid
       split-brain situations. It does this by having a	number	of  votes  as-
       signed  to each system in the cluster and ensuring that only when a ma-
       jority of the votes are present,	cluster	operations are allowed to pro-
       ceed.

       The library provides a mechanism	to:

       * Query the quorum status

       * Get a list of nodes known to the quorum service

       * Receive notifications of quorum state changes

       * Change	the number of votes assigned to	a node

       * Change	the number of expected votes for a cluster to be quorate

       * Connect an additional quorum device to	allow small clusters to	remain
       quorate during node outages.

VIRTUAL	SYNCHRONY
       Votequorum is the only one service where	communication with library  is
       allowed during synchronization phase. This makes	it possible for	quorum
       device to react to membership change and	decide to vote or not  without
       timing  hazard,	because	corosync stands	in synchronization phase until
       qdevice on all nodes votes or timeout expires.

       As a side effect, extended virtual synchrony is broken for the votequo-
       rum  service.  This  means,  that  messages sent	during synchronization
       phase can be delivered sooner then  messages  sent  right  before  sync
       phase began. This applies also for local	messages.

BUGS
       No  known bugs at the time of writing. The authors are from outerspace.
       Deal with it.

SEE ALSO
       corosync-quorumtool(8), votequorum(5), votequorum_initialize(3),	 vote-
       quorum_finalize(3),   votequorum_getinfo(3),  votequorum_trackstart(3),
       votequorum_trackstop(3),	votequorum_fd_get(3),  votequorum_dispatch(3),
       votequorum_context_set(3), votequorum_context_get(3), votequorum_setex-
       pected(3), votequorum_setvotes(3)

corosync Man Page		  2012-01-12		VOTEQUORUM_OVERVIEW(8)

NAME | OVERVIEW | VIRTUAL SYNCHRONY | BUGS | SEE ALSO

Want to link to this manual page? Use this URL:
<https://www.freebsd.org/cgi/man.cgi?query=votequorum_overview&sektion=8&manpath=FreeBSD+13.0-RELEASE+and+Ports>

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