Today I spent some time working on a relatively complex virtual machine setup (private domain + App-V server + App-V sequencing virtual machine + SCCM + SCOM). I had this all running on Hyper-V configured on a server core computer off in another room – and I was managing it from my Vista desktop.
The problem was that after an hour or so the performance of the virtual machines went down the drain. Windows were sluggish, simple operations were taking minutes, etc… I immediately started reviewing my configuration. I had created all of my virtual machines as dual-processor virtual machines, but as this was a quad core system it should be able to handle that fine. I was running the system a little tight on memory – but not so tight that it should be causing the sort of problems I was seeing.
I checked out performance counters – and got a lot of odd readings – but nothing that pointed to an obvious problem. So taking a stab in the dark, I recalled that I had recently changed the hard disk controller that was being used for my system disk – and decided to try moving it back to see if that changed anything.
I powered the system down remotely, grabbed my screw driver and tottered off to go and tweak the hardware. After a minute with the hardware the real problem became immediately obvious. A loose power cord had wedged itself into the CPU fan, and the CPU was running at ~10% capacity in an attempt to stop the whole computer from going up in smoke.
Once the cable was removed (and secured well away from the CPU fan) performance immediately returned to normal.
Now I just need to figure out how to get SCOM to monitor for hardware events so I can be notified about this kind of stuff in the future – without needing to do all the trouble-shooting ahead of time.