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 interface 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 exceptions: 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 reboot-
       ing 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),  votequorum_fd_get(3),  votequorum_dispatch(3), votequorum_con-
       text_get(3), votequorum_context_set(3),

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