| Bug #13494 | Log size differences create possibility of corruption | ||
|---|---|---|---|
| Submitted: | 26 Sep 2005 20:35 | Modified: | 30 Sep 2008 22:31 |
| Reporter: | C.J. Adams-Collier | ||
| Status: | Open | ||
| Category: | Server: InnoDB | Severity: | S4 (Feature request) |
| Version: | 4.0.24_Debian-10-log | OS: | Linux (Debian GNU) |
| Assigned to: | Heikki Tuuri | Target Version: | |
| Triage: | D5 (Feature request) | ||
[26 Sep 2005 21:50]
Heikki Tuuri
Hi! In your example case, no corruption can occur. InnoDB simply refuses to start with a log file of a wrong size. Further corruption CAN occur if mysqld crashes and the user tries to resolve the problem by deleting old ib_logfiles, or replacing them with wrong ib_logfiles. But then the database is probably corrupt anyway, because otherwise the user would have been happy with the automatic crash recovery of InnoDB. The main problem that I have observed is diagnosing the crashes that result from wrong logfiles. It is often difficult to tell why mysqld segfaulted. The following feature would solve this diagnosis problem: http://www.innodb.com/todo.php " Add more safety checks that would prevent one from using wrong ib_logfiles with ibdata files. InnoDB could once per minute stamp the current lsn to the trx system page in ibdata1, and at a startup compare the stamp to the log files, as well as to the shutdown lsn stamps in the ibdata files. " Regards, Heikki
[30 Sep 2008 22:31]
C.J. Adams-Collier
Thanks Heikki, Has this feature been implemented since last we spoke? Cheers, C.J.
Description: /etc/mysql/my.cnf contains a an innodb log size different than on-disk log file size: set-variable = innodb_log_file_size=20M $ ls -ld /var/lib/mysql/ib_logfile0 -rw-rw---- 1 mysql mysql 5242880 2005-09-18 05:10 /var/lib/mysql/ib_logfile0 $ sudo mysqld InnoDB: Error: log file ./ib_logfile0 is of different size 0 5242880 bytes InnoDB: than specified in the .cnf file 0 20971520 bytes! 050926 10:58:25 Can't init databases 050926 10:58:25 Aborting 050926 10:58:25 InnoDB: Warning: shutting down a not properly started InnoDB: or created database! 050926 10:58:25 mysqld: Shutdown Complete Syslog contents: --- Sep 26 11:07:55 norseth mysqld[15355]: InnoDB: Error: log file ./ib_logfile0 is of different size 0 5242880 bytes Sep 26 11:07:55 norseth mysqld[15355]: InnoDB: than specified in the .cnf file 0 20971520 bytes! Sep 26 11:07:55 norseth mysqld[15355]: 050926 11:07:55 Can't init databases Sep 26 11:07:55 norseth mysqld[15355]: 050926 11:07:55 Aborting Sep 26 11:07:55 norseth mysqld[15355]: Sep 26 11:07:55 norseth mysqld[15355]: 050926 11:07:55 InnoDB: Warning: shutting down a not properly started Sep 26 11:07:55 norseth mysqld[15355]: InnoDB: or created database! Sep 26 11:07:55 norseth mysqld[15355]: 050926 11:07:55 /usr/sbin/mysqld: Shutdown Complete --- The solution is to stop MySQL, change the line in my.cnf: set-variable = innodb_log_file_size=5M and re-start the daemon. After the daemon re-starts, stop it, move the log file out of the way, change the size in the my.cnf file, and re-start the daemon. This will re-set the size of the log file to whatever is in the config file. There is a lot of room for slip-up here. How to repeat: See above Suggested fix: There should be some sort of wrapper around the process. JamesDay tells me that this is one of the largest problems causing innodb corruption. If the log file is damaged, the database has a great potential to become corrupted.