General IT

MySQL mystery memory misuse.

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I have a small VPS server which hosts a couple of low traffic websites. I've been battling it for a couple of years, trying to reduce the memory consumption. The VPS has 0.5Gb RAM, and the same sized swap file. Sure, I could upgrade the VPS, but sometimes this geeky battling stuff is half the fun!

I've been using the two obvious Mysql tuning scripts and altering the configuration gradually over the last year or so. If you've ever looked at any of this yourselves you'll know them: mysqltuner.pl and  tuning-primer.sh
So the problem was this. I'd start up Mysql and it would eat up all the memory, start swapping, and eventually invoke oom_killer. The first change I made was to disable innodb. I didn't need it on this server, and immediately memory usage of MySQL dropped to about half. Now it would start up fine, and run for a week or two, but eventually it would crash out. It was using about 300Mb of the available 512Mb RAM, but would eventually use up all the swap as well. I set up monit to watch it and restart it when that happened, but that wasn't a great solution, so I started chipping away at the my.cnf file, to reduce memory footprint.

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Gnome System Log Viewer. No such file

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The default log viewer application that comes with Ubuntu, Mint etc, is called gnome-system-log. Sometimes it tries to display logs which don't exist and comes up with an error, eg: "Error when getting information for file '/var/log/mail.log': No such file or directory". However there is no obvious way to clear this message and stop it … Read more

WordPress update on nginx => 503 error

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It was a routine update, you've done it a thousand times. You select the plugins that need updating, hit update, and browse away while its all happening. Big mistake. You have to stay on the WordPress page for the update to finish. Now when you go to visit any page on your site, you see … Read more

ZTE USB Modem on Linux. Send SMS, Check Balance

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Seems like a lot of the information on the internet about this is out of date, and there is much old and unmaintained software. Here's what worked for me. I'm running Linux Mint 17, which is based on Ubuntu 14. This should also work on Debian.
So I have a SmartBro modem, which I use when my main internet connection breaks. A lot of the time it sits in my drawer, and I just top up the balance every 3 months with 30 pesos, to keep the number active. I can send the loads via online bank account, or coins.ph, or from any cornershop Loadz person, but how to check the balance when you're running Linux.
I've struggled with previous GSM modem interfaces before like Gnokii, and SMStools. This is waaaay simpler.

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