MySQL database high availability MHA about MySQL Learning

MHA is currently a relatively mature solution for MySQL high availability, developed by the Japanese Dena company Youshimaton, and is an excellent set of highly available software for failover and master-slave upgrading in MySQL high-availability environments. During the MySQL failover process, MHA can automatically complete the failover operation of the database within 0-30 seconds, and in the process of failover, MHA can ensure the consistency of the data to the maximum extent, in order to achieve a true sense of high availability.

MHA also provides the ability to switch between the main library and the current running main library to a new primary library (by upgrading from the library to the primary library) in about 0.5-2 seconds.

? Automatic fault detection and automatic failover

MHA is capable of monitoring MySQL in an existing replication environment, enabling automatic failover after a master failure is detected, by identifying the "new" Salve relay log and applying it to all slave, This allows MHA to ensure data consistency across slave, even if some slave have not received the latest relay log event when the main library crashes. Whether a slave node can become a candidate master node can be prioritized by configuring it in the configuration file. Because master guarantees data consistency across slave, all slave nodes have the hope of becoming the primary node. Data consistency issues that are very easy to produce due to replication disruption in a typical replication environment will not occur in MHA.

? Interactive (manual) failover

MHA can manually implement failover without having to ignore the master state, i.e. not monitoring the master state, confirming that the fault can be manually switched by MHA after the failure occurs

? Switch master to a different host online

MHA can switch between 0.5 and 2 seconds, and 0.5-2 seconds of write blocking is usually acceptable, so you can even switch master online during non-maintenance. Things like upgrading to a higher version, upgrading to a faster server, and so on, will become easier.

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MySQL database high availability MHA about MySQL Learning