MHA (Master High Availability) for MySQL

Sujith Jose <sjose@win2ix.ca> 
Win2ix Systems Inc. http://www.win2ix.ca

MySQL MHA tools are open source tools developed by Yoshinori Matsunobu which runs on top of MySQL and will help in the automatic master failover and the salve failover within few seconds. 

MHA is a wonderful tool and helps in the following

1) Automatic Master failover.
2) Easy to configure/install.
3) No need for extra servers thus saving cost.
4) Supports both asynchronous and semi-synchronous. 
5) No replication consistency problems. 
6) Faster slave promotion.
7) Scheduled online master switch.

Project top page: http://code.google.com/p/mysql-master-ha/

Documentation: http://code.google.com/p/mysql-master-ha/wiki/TableOfContents?tm=6

Source tarball and rpm package (stable release): http://code.google.com/p/mysql-master-ha/downloads/list 

We at Win2ix have extended the usage of this by creating an init script for ubuntu/debian systems using nohup command in tandem with the pid file.

Steps 
1) Copy the mhamanager file from this git repo to /etc/init.d location of your server 
2) Make the mhamanager file executable.
3) Edit the file and point your mha config file and mha log file to the correct location for the line  
	command_ls=`nohup masterha_manager --conf=/etc/app1.cnf < /dev/null >> /var/log/masterha/app1/app1.log 2>&1 &`
4) You are good and test the init script by running "/etc/init.d/mhamanager status"