Linux – How to force a MySQL table to become corrupted

corruptionlinuxmonitoringMySQLnagios

I have written a simple Nagios plugin that calls mysqlcheck (which checks for corrupted tables) and will give a warning if any are corrupt.

However none of my tables are corrupt now. So I'm not 100% sure that my plugin is working fine. I have a dev server that's not misson critical. How can I force one (or any) of the tables there to be corrupt so that I can test my nagios alert?

For the record the server is Ubuntu Dapper and the mysql is version 5.0

Best Answer

Generally you can't back up the databases by copying them from /var/lib/mysql and then copying them back because they get corrupted, you have to use mysqldump instead.

So if you go into one of the folders for the database in /var/lib/mysql, ie /var/lib/mysql/myDB/ and mess with some of the files that ought to do it :-)

So I would recommend copying one of the files, editing a little with a hex editor, and copying it back.

Related Solutions

Any good rsnapshot nagios plugins

i cannot really answer about rsnapshot but i use rdiff - similar tool.

there is couple of things i monitor with nagios for my backups:

what was exit code of last rdiff run. if it's not 0 - it means that something went wrong in the process. i just have simple bash script that executes bacup and depending on result touches file ok or failed. with nagios i check freshness of OK file and alert if it's older then 25h.
before running backup i touch file in /xyz/touched . on server that receives the backup i check freshness of that file. if it's older then 25h it means last night backup did not arrived to the receiving machine.
rdiff has verify option. i dont know if rsnapshot has. verify takes lot of time, i run it once a day and put result to a file... then simple nagios plugin greps this log file in search for error messages.

in this way i protect myself against interrupted backups and against file system corruption on receiving server ( for files not modified for long time ).

the trick is not to let nagios plugin do heavy lifting ( eg verifying the whole backup ), but rather schedule cron job that does that and have nagios plugin just checking result of the job ( eg file created or content of log file ).

and by the way - check this out.

Linux Bash – How to Sort du -h Output by Size

As of GNU coreutils 7.5 released in August 2009, sort allows a -h parameter, which allows numeric suffixes of the kind produced by du -h:

du -hs * | sort -h

If you are using a sort that does not support -h, you can install GNU Coreutils. E.g. on an older Mac OS X:

brew install coreutils
du -hs * | gsort -h

From sort manual:

-h, --human-numeric-sort compare human readable numbers (e.g., 2K 1G)

Best Answer

Related Solutions

Any good rsnapshot nagios plugins

Linux Bash – How to Sort du -h Output by Size

Related Topic