After upgrading to oneirc, and rebooting, system hangs during boot. Problem seems to be a bad interaction with upstart, udev, and lvm (device mapper) filesystems. Details below:
During boot, kernel appears to boot fully. Next set of messages show fsck running, and then a hang. Using the old init=/bin/sh trick, I can see that all of my file systems are now mounted, except one: a file system that lives on an lvm volume. I believe that, at this point, upstart is waiting for the lvm volume to come online... but of course, it can't/won't until lvm and the device-mapper run, which is typically done later, in the /etc/init.d scripts. (The mount point, a directory in /dev/mapper, hasn't yet been created). Commenting out the lvm volume in /etc/fstab allows the boot to proceed, more or less normally; the missing file system can then be mounted by hand.
With the above problem worked around, there is another alarming problem: much, much later in the boot, after a number of /etc/init.d scripts run, if finally gets around to running /etc/init.d/checkfs, which does an ... fsck! but with upstart, most all file systems are already mounted at this point, so the fsck crashes & burns. In the old SysV init scheme, this was correct: the fsck would not run until *after* the /etc/init.d/lvm2 scripts ran.
The clever sysadmin can work around these, but .. wow, it was hard and painful to figure out the above.
Thanks for taking the time to report this bug and helping to make Ubuntu better. Could you please add the log files from '/var/log/