Fedora upgrade recovery procedures?

[Dave Shaw]

I have an older Toshiba laptop running FC16. I also have a DVD with an
install .iso for FC17. I booted off the DVD, it noticed the existing
installation and offered to do an upgrade. About 5 minutes into the
upgrade process it had arrived at the point where it was about to
install the ~4000 packages. At that point it produced a message saying
there was insufficient disk space on /usr (short 2MB, this on a 12G
logical volume, with considerable space available on the physical
volume) and the install would exit.

Trying to reboot afterwards produces:
     sh: cannot set terminal process group (-1): inappropriate ioctl for device
     sh: no job control in this shell
and drops into a dracut shell.

Running the "rescue" operation on the DVD says it can't see any valid
Linux partitions. Nevertheless, there are other OSes on the disk and
booting into them suggests the Fedora LVM is intact (as well as the
Fedora boot partition, etc.), although /usr is *empty*.

So am I out of luck here, or is there some kind of recovery possible?
Maybe a Live-CD to do some amount of file tweaking? Does an upgrade
provide any recovery features at all? Is this the right mailing list
to post this question?

Thanks for any thoughts.