[linux-lvm] Resizing the root LVM partition

[Jonathan Morace <jmorace@gmail.com>]

I'm having a problem adding disks to my root partition, which is using
LVM.  The quick summary is that I think I need to run resize2fs on the
root partition, but I can't figure out how to unmount the root
partition to do so.

The longer version of the story...  I'm running Fedora Core 2, and
when I installed I had the root partition configured to be on two
disks using LVM.  I added two more disks to the computer and followed
the howto to initialize the disks, add the physical volumes to the
volume group, and extend the logical volume.  When I run "lvdisplay" I
see my logical volume is the correct size, but "df" only shows the
original size.  I'm assuming this is because I haven't done a
"resize2fs".  The reason I haven't is because I can't figure out how
to unmount the root filesystem in order to do this.  If I boot with
linux rescue, I can choose not to mount the filesystems, but then the
LVM devices don't exist.  I read somewhere that running "lvm vgscan -v
--mknodes" should do the trick, but as far as I could tell, no devices
were created.

Any ideas on how I can get the root partition resized to include the new disks?

Thanks for the help,

Jonathan