Linux

This was a really strange one and might be peculiar to debian servers. I was trying to change a couple of mysql default settings, so after editing the config file, I restarted mysql on a webserver and it didn't come back up again. There were a bunch of errors in the /var/log/mysql.log saying "errno: 24 – Too many open files". And in fact mysql was so busy pumping these errors out, that it didn't have time to do any databasing on the files it was able to open.

After a bit of experimentation (read 'panic'), I discovered that rebooting the server started mysql up fine, but doing a 'service mysql restart' produced the file errors, so I rebooted and left it running while I investigated.

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I was moving a WPMU site to a new server and saw that the database had grown to about 250Mb, and there were about 700 blogs running on the server. I used a few database queries to pull out a list of which blogs I wanted to delete — basically any which had a creation date and last update date the same, and any with only one post etc — at which point I had a list of 300 blog IDs. So was I going to manually delete them all? Nope, I did what any sensible person did, and wrote a script to do it.

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This is quickly becoming one of my favourite tools when setting up webservers, after discovering it recently. I have all sorts of monitoring set up and use munin a lot, but vnstat seems to be a very lightweight daemon which gives you insight into the traffic to and from your box. Best of all it integrates well with logwatch, so it will send you a quick report every day so you can see immediately if something is going wrong.

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