High Availability:Software:Configuration Database
The Toolpack configuration is located in a MySQL database.
High Availability
Database Connection
Since Toolpack is not necessarily running on the same host as the MySQL database, it uses sockets to connect to the database. To increase the reliability, Toolpack uses 2 database connections. If one becomes unavailable(example network is down), Toolpack can still connect to the database using the other sub net.
Database Replication
To protect against a loss of database, Toolpack uses the MySQL database replication feature. In a typical 2 hosts redundancy setup, the primary and secondary hosts will run a Toolpack system and a MySQL database. At start up, Toolpack will configure one database as master database, the other as slave. Once the database configuration is done the master database will copy itself in the slave database. After that, any changes made on the master database will then get replicated on the slave database.
The following figure illustrates the database setup in a high availability system:
It is interesting to note that both Toolpack system always access the same database.
The next image shows a database switchover:
When the primary database becomes available again, Toolpack sets it as replication slave. There is no database switch back as illustrated with the following image:
