bionic (8) votequorum_overview.8.gz

Provided by: libvotequorum-dev_2.4.3-0ubuntu1.3_amd64 bug

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 assigned to each system in the cluster
       and ensuring that only when a majority of the votes  are  present,  cluster  operations  are  allowed  to
       proceed.

       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  votequorum  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),       votequorum_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_setexpected(3),
       votequorum_setvotes(3)