HA Setup for MySQL/mostly MyISAM Tables

Question

I am currently using Master-Slave Replication, seperating reads from writes at the application level.
The only kind of failover currently implemented is application level detection of master failure, making the slave the new master so the application can run uninterrupted.
As one can guess, it is a lot of work to switch back, get in sync, tidy up and so on.

I have searched alot, and read dozens of articles, but i did not come across a solution for HA MySQL if you have mostly MyISAM Tables, Mysql Cluster, Heartbeat/DRBD, Schooner, these are all fine for InnoDB-only setups, but not suitable for MyISAM.

I would appreciate some suggestions or real-world experience with HA Setups.
It does not need to be open-source (read free), it just needs to work.

Answer 1

We use MMM combined with circular replication.

We have two MySQL servers (foo-db1, foo-db2) and each is slaved to the other, so an update on any one will be sent to the other:

http://onlamp.com/onlamp/2006/04/20/advanced-mysql-replication.html

Now that each instance has the data, we've found that it's best that writes only go to one. To accomplish this we create a virtual IP (vIP) under a different service hostname (foo-db) that clients send INSERTs and UPDATEs to. Under Debian you would install the "mysql-mmm-agent" package and generally follow this guide:

http://mysql-mmm.org/mmm2:guide

We use this configuration on most of our web sites: two front-end web servers talking to two back-end database servers. The MMM monitor runs on one of the web servers (which one is determined by Heartbeat):

www.howtoforge.com/high-availability-load-balancer-haproxy-heartbeat-debian-etch

So in summary: use circular replication to make sure two (or more?) MySQL servers are in sync; use MMM to control where the database service vIP lives; use Heartbeat to make sure the MMM agent only runs on one machine at a time.