Here are release notes.
* Supporting RESET SLAVE ALL from MySQL 5.5.16
* Supporting "skip_reset_slave" parameter to avoid running CHANGE MASTER TO on the promoted slave
* Doing master's health checks optionally via MySQL CONNECT, in addition to SELECT
* Supporting "mysql --binary-mode" from MySQL 5.6.3
* Supporting ssh_host and ssh_port parameters
* Supporting ssh_options parameter
* Supporting --check_only for online master switch (dry-run)
* When doing online master switch, MHA checks whether long queries are running on the new master. This is important to reduce workloads on the new master. Query time limit can be controlled via --running_seconds_limit.
When executing SIGINT on online master switch, MHA tries to disconnect established connections via MHA.
* Additionally checking replication filtering rules on online master switch
* MHA Manager looks for relay-log.info in wrong location when setting relay_log_info_file
* Wrong option for master_ip_failover_script
* Timeout settings for SSH connection health check does not always work
* Modifying a rpm spec file to create valid rpm package for 64bit RHEL6
* Forcing more strict ssh checking. Originally MHA checks master's reachability by just connecting via SSH and exiting with return code 0. This in some cases does not work especially if SSH works but data files are not accessible. In this fix, MHA checks master's ssh reachability by executing save_binary_logs command (dry run). MHA Client also needs to be updated to 0.53.
* Zombie process remains on master ping timeout
* Do not execute SET GLOBAL read_only=(0|1) if not needed
How to upgrade
Upgrading MHA from older version to 0.53 is easy. Simply stop masterha_manager program, replace all MHA Node and MHA Manager packages to 0.53, and restart masterha_manager. You do not need to stop mysqld or MySQL Replication.
MHA for MySQL, project Info
Project top page: http://code.google.com/p/mysql-master-ha/
Source tarball, deb and rpm packages (stable release): http://code.google.com/p/mysql-master-ha/downloads/list
The latest source repository (development tree, url changed): https://github.com/yoshinorim/mha4mysql-manager (Manager source) and https://github.com/yoshinorim/mha4mysql-node (Per-MySQL server source)
Commercial support for MHA is available from SkySQL.