http://dev.mysql.com/doc/refman/6.0/en/drbd-linux-heartbeat.html
A.14.2. Linux Heartbeat
In the following section, we provide answers to questions that
are most frequently asked about Linux Heartbeat.
Questions
23.14.2.1:
What is Linux Heartbeat?
23.14.2.2:
How is Linux Heartbeat licensed?
23.14.2.3:
Where can I download Linux Heartbeat?
23.14.2.4:
If I find a bug with Linux Heartbeat, to whom do I submit
the issue?
Questions and Answers
23.14.2.1:
What is Linux Heartbeat?
The Linux-HA project
(http://www.linux-ha.org/) offers a high
availability solution commonly referred to as Linux
Heartbeat. Linux Heartbeat ships as part of several Linux
distributions, as well as within several embedded high
availability systems. This solution can also be used for
other applications besides databases servers, such as mail
servers, web servers, file servers, and DNS servers.
Linux Heartbeat implements a heartbeat-protocol. A
heartbeat-protocol means that messages are sent at regular
intervals between two or more nodes. If a message is not
received from a node within a given interval, then it is
assumed the node has failed and some type of failover or
recovery action is required. Linux Heartbeat is typically
configured to send these heartbeat messages over standard
Ethernet interfaces, but it does also support other
methods, such as serial-line links.
23.14.2.2:
How is Linux Heartbeat licensed?
Linux Heartbeat is licensed under the GPL.
23.14.2.3:
Where can I download Linux Heartbeat?
Please see
http://linux-ha.org/download/index.html.
23.14.2.4:
If I find a bug with Linux Heartbeat, to whom do I submit
the issue?
Bug reports should be submitted to
http://www.linux-ha.org/ClusterResourceManager/BugReports.