Troubleshooting of the fail-safe session store

Usually the slave stops replication if an error occurs. You can check the state of the slave with the sql command:

show slave status\G

If replication has stopped, usually the error that caused it will be displayed. First you should try to fix the error. If this is not possible, you can do a "forced" restart of the slave like this:

• On the master call do this (to display the current state of the master):

MariaDB [replicated_session_store]> show master status\G
*************************** 1. row ***************************
File: mariadbmaster-bin.000131
Position: 194630804
Binlog_Do_DB:
Binlog_Ignore_DB:
1 row in set (0.00 sec)

• On the slave do this (using the values returned by the call "show master status\G" on the master):

STOP SLAVE
CHANGE MASTER TO
MASTER_LOG_FILE='mariadbmaster-bin.000131',
MASTER_LOG_POS=194630804;
START SLAVE;

In this way, the system will restart the slave, without replicating to the slave all sessions that occurred from the moment replication has stopped until now.

If the recognition whether a service is down takes too long, you can adapt the following parameters in the ConnectString attribute of the concerned MySQLSessionStoreServlet:

• connect_timeout: Connect timeout in seconds
• ping_timeout (in seconds): If the ping call (including connect) to the database does not return after <ping_timeout + connect_timeout> seconds, we assume that the DB is down.

See also the table MysqlSessionStoreServlet configuration.