Off the record - Craig Box

Once upon a time, there was a race condition between udev and device-mapper (the kernel interface used for EVMS and LVM2). DM would create and destroy devices regularly, say in the action of creating an LVM snapshot, and udev would say "ooh, shiny new device created" and try and do stuff with it, only to find it had gone away.

For some time, the fix for Ubuntu was a udev rule instructing it to ignore dm-N devices, as such:

KERNEL=="dm-[0-9]*", OPTIONS+="ignore_device"

All well and good, until they fixed that bug in Feisty. Now, if you still have that option in your udev rules, you will get LVM snapshots taking 10 minutes to create, and you'll also get LVM not starting properly at boot.

Check your workarounds when you upgrade packages. Sometimes, they not only don't work around any more, they cause all new problems.