Video: Building a MySQL Slave and Keeping it in Sync At the Boston MySQL User Group Sheeri Cabral presented on how to get a consistent snapshot to build a slave, how to use mk-table-checksum to check for differences between masters and slaves on an ongoing basis, and how to use tools such as mk-table-sync and mysqldump to sync the data if there are any discrepancies. This link contains the slides and the videos

Do you have a master-slave MySQL set up?  Ever do DDL changes on the master?  You may be hit with a serious data integrity bug.  Read on.One of our clients does a regular "rename tables" on the master to keep the current table small and archive off old data.  We'd occasionally be hit by a 'duplicate key' error on the slave on the current table and have to resolve it manually.  Digging into the issue, I managed to replicate it on demand and filed bug 39675 with MySQL, which subsequently has been verified and slated for fix, though from what it seems only in version 6.0.  The bug affects all versions of MySQL from 4.1 to 6.0.In a nutshell, here is what happens. The "rename tables" command only checks for pending transactions or locks in the current session.  If there is a pending transaction in another session on the table being renamed, the rename will succeed, but the order in which the transaction is written  []

Slaves can be used for:Horizontal read scalability -- take the load off a master database by spreading reads to a replicated slave.Disaster recovery -- some disasters, such as a hardware failure, can be solved by having a slave ready to propagate to a master. This technique also works to make offline changes to a master/slave pair without having database downtime (see below).Consistent Backups -- without disrupting production usage, a slave can be used to ta