"Before we start, let’s quickly cover the architectural
configuration of your two servers, and talk about performance.
Firstly, you are going to use two “commodity” servers,
which is not to imply slow or generic. You want to dedicate your
fastest servers, because this type of configuration comes at a
cost; it is doing much more than you may think a primary/secondary
failover setup would. Therefore, I/O capabilities are probably the
most important aspect. As Florian Haas of LINBIT (the creators of
DRBD) points out, you can run two separate instances at once to
avoid under-utilizing your secondary server. Each node will be the
primary for its main instance, and a secondary for the other
node.
"Second, conceptually, you will configure MySQL to live on a
DRBD replicated device. Heartbeat will monitor MySQL availability,
and in the event a failover is necessary, the secondary server will
mount the file system, steal the virtual IP, and start up
MySQL."
