MySQL relay logs are saved in volatile filesystem /var/run

[David Leadbeater]

Binary package hint: mysql-server-5.0

When using replication the MySQL relay logs are saved under /var/run, as this is a tmpfs filesystem it can fill up and replication will stop working (also I think this might affect recovery in the case of a system crash).

A default like:
relay-log=/var/log/mysql/mysqld-relay-bin.nnnnnn
in the my.cnf file would be good.

[Soren Hansen (soren)]

Sorry, my comment got lost somehow.

My mysql server already puts it under /var/lib/mysql. Could you check what your datadir is set to? ("mysqladmin variables" reveals it)

[wayne (wayne-flashmedia)]

Heres a me too comment, I have the same problem on two servers.

To answer the question my datadir is /var/lib/mysql.

[wayne (wayne-flashmedia)]

Heres a bug I found on Mysql's site. The version numbers not the same but the symptoms are.

http://bugs.mysql.com/bug.php?id=28850&error=lp

[David Leadbeater (launchpad-net-dgl)]

Yes, that looks like the problem. The MySQL docs don't match the behavior of the server.

This also affects log-bin, but this is specified in the my.cnf shipped by Ubuntu so the issue isn't seen.

(Just a note for anyone else experiencing this: if you do update the config file you need to also move the files and you need to update the locations in /var/lib/mysql/relay-log.info and (the newly copied) /var/log/mysql/mysqld-relay-bin.index, they are just text files.)

[Ante Karamatić (ivoks)]

This is major bug. MySQL replication is useless, even with datadir set to /var/lib/mysql, in Feisty.

I can solve this only with setting pid-file to /var/lib/mysql/mysql.pid :/

[Launchpad Janitor (janitor)]

This bug was fixed in the package mysql-dfsg-5.0 - 5.0.51a-3ubuntu5

---------------
mysql-dfsg-5.0 (5.0.51a-3ubuntu5) hardy; urgency=low

  * debian/patches/59-fix-mysql-replication-logs.dpatch:
    Fix mysql replication: relay-logs were stored in /var/run. (LP: #119271).
    Patch taken from 5.0.54.
  * debian/patches/58-disable-ndb-backup-print.dpatch:
    update description of ndb_backup_print patch.

 -- Mathias Gug <email address hidden> Thu, 27 Mar 2008 19:02:38 -0400

[Arjen Lentz (arjen-lentz)]

See http://arjen-lentz.livejournal.com/115899.html for more background info and a workaround through the my.cnf.

[Jeremy Jackson (jerj)]

The *fix* released breaks an existing replication setup when going from Gutsy to Hardy. I had to manually move the relay logs from /var/run/mysqld to /var/lib/mysql, and edit relay-log.info and mysqld-relay-bin.index. But it did work, and saved me re-syncing the whole db.