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diff --git a/man/votequorum_overview.3 b/man/votequorum_overview.3 new file mode 100644 index 0000000..4ec1b75 --- /dev/null +++ b/man/votequorum_overview.3 @@ -0,0 +1,84 @@ +.\"/* +.\" * Copyright (c) 2008, 2012 Red Hat, Inc. +.\" * +.\" * All rights reserved. +.\" * +.\" * Authors: Christine Caulfield <ccaulfie@redhat.com> +.\" * Fabio M. Di Nitto <fdinitto@redhat.com> +.\" * +.\" * This software licensed under BSD license, the text of which follows: +.\" * +.\" * Redistribution and use in source and binary forms, with or without +.\" * modification, are permitted provided that the following conditions are met: +.\" * +.\" * - Redistributions of source code must retain the above copyright notice, +.\" * this list of conditions and the following disclaimer. +.\" * - Redistributions in binary form must reproduce the above copyright notice, +.\" * this list of conditions and the following disclaimer in the documentation +.\" * and/or other materials provided with the distribution. +.\" * - Neither the name of the MontaVista Software, Inc. nor the names of its +.\" * contributors may be used to endorse or promote products derived from this +.\" * software without specific prior written permission. +.\" * +.\" * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" +.\" * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE +.\" * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE +.\" * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE +.\" * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR +.\" * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF +.\" * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS +.\" * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN +.\" * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) +.\" * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF +.\" * THE POSSIBILITY OF SUCH DAMAGE. +.\" */ +.TH VOTEQUORUM_OVERVIEW 3 2012-01-12 "corosync Man Page" "Corosync Cluster Engine Programmer's Manual" +.SH NAME +votequorum_overview \- Votequorum Library Overview +.SH 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. +.PP +The library provides a mechanism to: +.PP +* Query the quorum status +.PP +* Get a list of nodes known to the quorum service +.PP +* Receive notifications of quorum state changes +.PP +* Change the number of votes assigned to a node +.PP +* Change the number of expected votes for a cluster to be quorate +.PP +* Connect an additional quorum device to allow small clusters to remain quorate during node outages. +.PP +.SH 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. +.SH BUGS +No known bugs at the time of writing. The authors are from outerspace. Deal with it. +.SH "SEE ALSO" +.BR corosync-quorumtool (8), +.BR votequorum (5), +.BR votequorum_initialize (3), +.BR votequorum_finalize (3), +.BR votequorum_getinfo (3), +.BR votequorum_trackstart (3), +.BR votequorum_trackstop (3), +.BR votequorum_fd_get (3), +.BR votequorum_dispatch (3), +.BR votequorum_context_set (3), +.BR votequorum_context_get (3), +.BR votequorum_setexpected (3), +.BR votequorum_setvotes (3) +.PP |