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.
reads its configuration from the objdb. The following keys are read when it starts up:
Most of those values can be changed while corosync is running with the following exceptions:
cannot be changed, and
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.
This software is not yet production, so there may still be some bugs.