Recently my web host (Gradwell) moved to a new hosting platform (Apache 2, php 5.2) to try and bring things up-to-date. In general, the end result worked okay. However, the load balancing they had in front of their web cluster was apparently sub-par. This became entirely apparent when a single customer was able to bring the whole thing to a grinding halt with some kind of chess related website.
Now, I know it’s shared hosting, and you have to take the performance hits every now and then, but there’s a difference between ‘takes 2 or 3 seconds longer sometimes’ and ‘didn’t load’, ‘won’t load’, ‘took 8 minutes’. I raised a ticket on the Friday when the problems got to their worst, but for reasons I’m not sure about, that didn’t get looked at by anyone technical until Monday. So from Friday to Monday all my Gradwell sites were basically unusable between 1pm and 8pm UK time.
Gradwell made some changes on Monday and spoke to the owner of the other site, but it didn’t really fix the problem. Eventually they decided to replace whatever load balancer they were using with a Squid reverse proxy, which had been running ‘fine’ in front of their php4 cluster. They did this Tuesday night and since then the site has been a lot quicker.
However, it broke WordPress. Let me explain.