Dreamhost Loading Issues

Dreamhost, where this site is hosted, seem to be having a bit of bother at the moment; I’ve heard of a some people walking away from this once-excellent webhost because their shared servers are heavily overloaded.

I’m not sure what Dreamhost are doing with these shared machines, but they certainly do seem to be overloaded. I wanted to know the high loads I’d observed on my shared machine were a blip, or if they were predictable in some way.

So, I noted the load values over the weekend. I grabbed the one-minute load values, and plotted them. I wasn’t smart about this, so I haven’t noted exact dates for points, etc. This was a simple loop which woke up each minute and asked for the machine’s load. Once I was done, I piped the results into gnuplot.

The full data collected looks like this (you can click for a larger version):

These load spikes look inherently unpredictable to me. Not much of a pattern there, but there are many points considerably over a load factor of 4. (This is a 4-core machine, so I’d expect to see a load of 4 or less.) Sorting them, you can see that there are many spikes in the first graph well over this preferred maximum:

In fact, it’s overloaded about one third of the time. Grabbing the final hour of output for comparison, it’s easy to see that there’s not even a useful trend at this scale:

Sorting them again, we see that this machine is overloaded on nearly half of those samples taken:

The numbers I’ve presented here are anecdotal, but are on the low side when compared to some others. I’m not sure if Dreamhost really acknowledge a problem here, but this seems to have affected a few people hosted over there.