I'm running WP 3.1.4 with the domain mapping plugin and 16 domains. The domains are new, most have no posts, and in total the network is probably getting less than 20 hits per day. I'm just using the default twentyten theme. I'm on a dedicated server, dual Pentium G6950 / 2GB RAM / linux RHE 5.6 64 bit. I do have other sites on the server however my server load typically fluctuates around 0.02-0.3
I had several plugins on this wordpress install, and yesterday I tried opening the Dashboard links for every site in rapid succession, and I noticed my server load began to climb rapidly. Not all sites opened, the load climbed to ~300, and I had to reboot the server after it became unresponsive. To make sure it wasn't coincidence, I repeated and saw the same results. I eventually removed all plugins except for the domain mapping plugin, and by doing this I was able to successfully open all Dashboard links, however I noticed strange behavior.
Only after all of the Dashboards had loaded, the server load begins to climb. It typically climbs to around 25 or so, and then begins to slowly drop. Keep in mind that I have no activated plugins, other than the domain mapping. I can open the index page of each site without seeing any measureable increase in server load, it's only the Dashboard which causes this.
I suppose the most obvious solution would be to not open a bunch of dashboards at the same time, however I am concerned about this being an indication of future problems as I continue to expand my network.
Any ideas what might be causing this problem?