MySQL Bugs: #16202: Add support for multiple InnoDB log file locations

Bug #16202	Add support for multiple InnoDB log file locations
Submitted:	4 Jan 2006 20:29	Modified:	13 May 2010 16:03
Reporter:	Rob Blick	Email Updates:
Status:	Verified	Impact on me:	None
Category:	MySQL Server: InnoDB storage engine	Severity:	S4 (Feature request)
Version:	5.0	OS:	Linux (Linux)
Assigned to:		CPU Architecture:	Any

Description:
There currently does not appear to be a way to write multiple copies of the InnoDB log files (or if there is, I don't see it documented).  One can use innodb_log_group_home_dir to specify a location for all the InnoDB log files, but multiple locations cannot be specified.  Without multiple copies, what happens if (you're very unlucky and) your server crashes in the middle of a write to the active innodb log file?  The log file may be corrupted, and InnoDB cannot recover.  Or a more probable scenerio... what if the filesystem on which the log files are stored gets corrupted (e.g., media crash, etc)?  With multiple copies of the log files (as provided by Oracle), you're protected from these catastrophies.

How to repeat:
Not a bug - feature request.

Suggested fix:
Add support for multiple log file locations.  For example, modify the innodb_log_group_home_dir option to support the following:

innodb_log_group_home_dir=/u01, /u02, /u03

which would cause the InnoDB log files to be mirrored on the three distinct filesystems at /u01, /u02, and /u03.  Or, if this is already permitted, simply update the documentation.

Thank you for a feature request. Yes, innodb_log_group_home_dir allows to specify only one location, and the ability to place 2 or more copies of the same log (as in Oracle) onto different directories (and devices) is surely useful.