VOTEQUORUM_OVERVIEW(8)     Corosync Cluster Engine Programmer's Manual     VOTEQUORUM_OVERVIEW(8)



NAME
       votequorum_overview - Votequorum Library Overview

OVERVIEW
       The  votequuorum library is delivered with the corosync project. It is the external inter‐
       face to the vote-based quorum service. This service is optionally loaded into all ndes  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.

       votequorum reads its configuration from the objdb. The following keys  are  read  when  it
       starts up:

       * quorum.expected_votes
       * quorum.votes
       * quorum.quorumdev_poll
       * quorum.disallowed
       * quorum.two_node

       Most  of  those  values can be changed while corosync is running with the following excep‐
       tions: quorum.disallowed cannot be changed, and two_node cannot be set on-the-fly,  though
       it  can be cleared. ie you can start with two nodes in the cluster and add a third without
       rebooting all the nodes.

BUGS
       This software is not yet production, so there may still be some bugs.

SEE ALSO
       corosync-quorumtool(8),   votequorum_initialize(3),    votequorum_finalize(3),    votequo‐
       rum_fd_get(3),    votequorum_dispatch(3),    votequorum_context_get(3),    votequorum_con‐
       text_set(3),

corosync Man Page                           2009-01-26                     VOTEQUORUM_OVERVIEW(8)