Comment 23 for bug 579858

Clint, yes that may well be the case. I had assumed that the only recently active for writing files would have been in /var as it had been well over the 30 sec commit time since any changes/updates had been performed. However, I had not considered something like libc6 being held open by something active.
I was surprised by how suddenly it went off, as usually you get a brief glimpse of the power off message, so wondered if umount or its calling process was crashing out badly, and could have otherwise done something more to commit the file system cleanly.