MySQL Database Recovery

I recently had a key application server die (hardware). One of the key applications running on this machine was a web-application that used a MySql database. We did have some specific MySql backup files, but the most recent backup of the data was a complete server backup of all files.

This meant that I had to work out how to restore a MySql database from the files stored in the data folder (under MySQL Server5.0/data/)

The files I had were:

ib_logfile0
ib_logfile1
ibdata1
and a folder, my_application, which contained a whole bunch of .frm files describing the table structures.

To restore MySql I started by copying these three files and one folder into a newly installed MySql folder on a replacement server. However, on starting mySql as a service, I got:

Could not start the MySQL service on Local Computer.
Error 1067: The process terminated unexpectedly.

I then checked out more information about this error in the file named machineName.err in the MySql/data folder.

This showed that:

InnoDB: Error: log file .\ib_logfile0 is of different size 0 25165824 bytes
InnoDB: than specified in the .cnf file 0 1782 57920 bytes.
080917 12:30:17 [ERROR] Default storage engine (InnoDB) is not available
080917 12:30:17 [ERROR] Aborting.

In this case, I went to my.ini file and changed:

innodb_log_file_size=170M

to

innodb_log_file_size=25165824

I was then able to start the MySql Server and create a normal backup for later retrieval on other servers.