There are two main ways that the data on the Master-DB can become corrupted.
If you think that your database is corrupted, you have probably already noticed odd behavior that's probably related to your database. If it's disk or filesystem corruption you'll probably see error messages in the instance log such as syslog-related or even mysql-server related. If the corruption is caused by a bug in the application, you'll probably notice that data is missing or get application errors complaining about missing relationships, records not found, or failed transactions.
The plan of action changes dramatically depending on the two cases:
When the data corruption is local to the Master-DB such as disk errors, filesystem errors, etc., it's likely that the problem does not affect the Slave-DB instance. In this case, you can use the Slave-DB for recovery since it has the most recent copy of the non-corrupted data. In this situation, the recovery is the same as when the Master-DB instance failed.
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