F15 to F16 upgrade via DVD does not recognize previous installation

[Deron Meranda]

I'm attempting to upgrade a Fedora 15 installation using the F16 DVD.
However anaconda is never giving me a choice to upgrade; instead it
assumes I only want to install fresh, and takes me to a screen where I
must chose a disk layout/partitioning scheme.  I've upgraded Fedora
many many times in the past, and this is the first time I've
encountered this situation.

I've double-checked my /etc/redhat-release using "rpm -v --verify
fedora-release", and which contains:
   Fedora release 15 (Lovelock)

My current F15 system, using the x86-64 arch, was completely up to
date on all updates prior to attempting the upgrade.

The DVD I'm booting from is: Fedora-16-x86_64-DVD.iso


It does seem to recognize my hard drives and previous partition/LVM
configurations, because it is asking for my LUKS passphrases on
various logical volumes while it is scanning the storage devices.

Note that there is a little annoyance, in that my swap logical volume
is using a randomized LUKS password (e.g., crypttab uses /dev/urandom)
- but anaconda either requires a permanent fixed password, or you must
skip that volume.  I simply chose to skip accessing swap, and it then
continued on to asking for the LUKS passwords for my other volumes,
which I provided.

Briefly, I have two local hard drives. The first has a small /boot
partition (~500 MiB), and a second huge partition that is an LVM
volume group. The second drive is entirely an LVM volume group (a
different VG). Then all my other filesystems except /boot are
individually LVM logical volumes. Each logical volume is then LUKS
encrypted separately, with /etc/crypttab configured appropriately.


What is the likely cause for the DVD not offering to upgrade my F15
installation, and how can I make it do so?

Thanks
-- 
Deron Meranda
http://deron.meranda.us/