Spontaneous reboots

Yesterday, I stepped into my office, sat down to my Dell T7500 workstation, and noticed that the machine had hung on boot. I had left it on, so the boot had been initiated during the night. The error message said: “No boot device found.”

I made a mental list of what might be wrong:

• Failure of the Samsung solid state boot disk.
• SATA controller failure
• Bad or intermittent connection between the controller and the desk (bad cable, bad connectors, etc.)

I powered down the machine and powered it back up again. This time it booted. “Can’t fix it if it’s not broken,” I said to myself, and started to work.

The computer did another spontaneous reboot about four hours later. This time it didn’t hang looking for the solid-state disk.

I thought about opening the computer and fiddling with the cables, then maybe calling Dell (I have on-site service for this machine), but then I had another thought. In the past I had seen machines spontaneously reboot when they were connected to APC UPSs with aging batteries. The UPS is supposed to detect when the battery is going bad, but it doesn’t appear to always do so. You wouldn’t think that a bad battery would cause problems in the output if there were no power failure, but I had seen it several times in the past.

I replaced the APC SmartUPS 1000XL on the T7500 with another UPS. It’s been more than 24 hours, and I haven’t seen a spontaneous reboot. It’s too soon to call the problem fixed, but things are looking good.

Next time you experience spontaneous reboots, check out your UPS.