When running replication, two new files appear in your data directory: master.info and relay-log.info. MySQL uses these files to save information about your replication state, and they’re used when MySQL starts up, if they’re available.

Caution MySQL considers the information contained in the master.info and relay-log.info filebefore looking for settings in the configuration files. This means that changes in your my.cnf file may beignored, if the information is stored in the info files.

Both of these files provide information about the configuration and status of your replica-tion, but shouldn’t be used as configuration files to make changes. The primary purpose forthese files is to keep state information between database restarts, and for database backups.The slave threads control both of these files, and you should only use them for information.You can make changes to these files with the CHANGE MASTER command, which is discussed inmore detail in the section “CHANGE MASTER.”