Disablingbinlog_checksumforMySQL5.5/5.6master-masterre_MySQL

Last_IO_Error: Got fatal error 1236 from master when reading data from binary log: ‘Slave can not handle replication events with the checksum that master is configured to log; the first event ‘bin-log.002648’ at 4, the last event read from ‘/var/lib/mysqllogs/bin-log.002648’ at 120, the last byte read from ‘/var/lib/mysqllogs/bin-log.002648’ at 120.’

Why did this happen? Starting in MySQL 5.6.6, the newbinlog_checksumoption defaults toCRC32. Since that option did not exist in MySQL 5.5, the replica can’t handle the checksums coming from the master. Therefore I recommend settingbinlog_checksum=NONEin my.cnf as part of the upgrade process for a master-master setup to avoid this error.

My fix was to run this on the passive master:

set global binlog_checksum='NONE';

Then I added this to my.cnf so it would survive a restart:

binlog_checksum=NONE

After that change was made I examined the binary log to confirm that it did not include anything other than pt-heartbeat activity, and then executedCHANGE MASTERon the active master to skip the checksummed events.

Once the other master is upgraded I can go back and consider changingbinlog_checksumtoCRC32.