0

I have to setup a MySQL slave on an other infrasctructure. It will become the Master once that other infrasctructure is ready.

Mysql 5.6.29 Slave A in old infrasctructure Slave B in new one

I dumped the Slave A database by performing a STOP SLAVE;, FLUSH TABLES WITH READ LOCK then the mysqldump and restarted the slave with START SLAVE. I've now a perfect dump of my slave A with the master binlog and its position.

I dumped the dump into the Slave B and setup the correct binlog and position for the replication. Once started, the Slave B couldn't find the binlog. But they are all in the right /var/lib/mysql folder on the Slave A. When I say they are all there I mean I put them myself in the folder in fact, otherwise they are deleted (I don't know why).

I really don't understand what I'm missing here.

log-slave-updates is ON on the Slave A

Improve this question
3
  • The error message is Got fatal error 1236 from master when reading data from binary log: 'Could not find first log file name in binary log index file' Is both Mysql but Slave A is on Debian and the other in AWS RDS MySQL. I cannot check the my.cnf of the AWS RDS. @RolandoMySQLDBA suggests something: dba.stackexchange.com/questions/87002/…
    – Kaymaz
    Commented Dec 9, 2017 at 15:33
  • Do you intend to hook B to A (daisy-chain)? Or B to the Master?
    – Rick James
    Commented Dec 9, 2017 at 17:02
  • Master -> A -> B. When I can begin the migration, B will become Master. Old Master and A will be killed.
    – Kaymaz
    Commented Dec 9, 2017 at 18:02

2 Answers 2

Reset to default
1

Master -> A -> B

binlog on A needs to be turned on.

B must use the binlogs from A, not from the Master.

So...

  1. Turn on binlogging on A.
  2. Stop replication from Master -> A.
  3. Dump A
  4. Load dump onto B
  5. CHANGE MASTER to point B to A.
  6. Start replication from Master -> A. Things should flow all the way to B.
Improve this answer
5
  • Except that the binlogs on A are not there anymore. Can I change the mysql-bin.index on A?
    – Kaymaz
    Commented Dec 9, 2017 at 18:38
  • You can't hang a slave off of A without having binlogging turned on. With A stopped, you can safely have an "empty" binlog and the index. But "no" binlog sounds like disaster - especially if A does not write binlogs after step 6.
    – Rick James
    Commented Dec 9, 2017 at 18:47
  • The backup is done during the night. And in the morning, the binlog file on A referred to in the dump file is not there anymore.
    – Kaymaz
    Commented Dec 9, 2017 at 18:57
  • 1
    What is purging it? Not MySQL in less than a day -- see expire_logs_days. Or are you referring to the "relay" logs, which are not relevant.
    – Rick James
    Commented Dec 9, 2017 at 19:55
  • There must be something but I don't find it! expire_logs_days is not set at all in the confi which means it's 0 (no delete). There is a hole of 13 binlogs missing between today 8.30am and 9pm. Hopefuly I backup the binlogs on A...
    – Kaymaz
    Commented Dec 9, 2017 at 20:11
0

I finally managed to daisy-chain.

  1. Since the binlogs were removed, I copied rsync them each 30 seconds
  2. Dump Slave A to Slave B
  3. Stop MySQL server service mysql stop
  4. Copy back the deleted binlogs on Slave A in the MySQL data folder
  5. Add the binlogs file name in [mysql-bin].index
  6. Start Slave A service mysql start and the replication
  7. Start the replication on Slave B
  8. Monitor with SHOW SLAVE STATUS on A and B
Improve this answer

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.