Fedora Users — Re: How do I switch LVM disks?

Neal Becker wrote:

I got a new disk, and created LVMs on it. I copied the filesystems OK.But, how do I get the new disk mounted as /? For that matter, what

determines what LVM gets mounted where?  I'm guessing it's part of the LVM
information.  I noticed that system-config-lvm has options to select where
logical partitions get mounted.

I hope I don't need to switch it by editing with system-config-lvm - because
if I mess that up, I'm basically screwed.

I tried editing grub.conf:

title Fedora Core (2.6.15-1.1948_FC5)
        root (hd0,2)
        kernel /vmlinuz-2.6.15-1.1948_FC5 ro root=/dev/VolGroup00/LogVol00
rhgb quiet
        initrd /initrd-2.6.15-1.1948_FC5.img
title Fedora Core (2.6.15-1.1948_FC5)#2
        root (hd0,2)
        kernel /vmlinuz-2.6.15-1.1948_FC5 ro root=/dev/7200rpm/LogVol02 rhgb
quiet
        initrd /initrd-2.6.15-1.1948_FC5.img

But if I select #2 it panics saying it can't find /dev/root, (or something
like that).
Here's some info:
lvm> lvscan
  ACTIVE            '/dev/7200rpm/LogVol03' [2.00 GB] inherit
  ACTIVE            '/dev/7200rpm/LogVol02' [53.50 GB] inherit
  ACTIVE            '/dev/VolGroup00/LogVol00' [53.59 GB] inherit
  ACTIVE            '/dev/VolGroup00/LogVol01' [1.94 GB] inherit
lvm> pvscan
  PV /dev/hdb4   VG 7200rpm      lvm2 [55.50 GB / 0    free]
  PV /dev/hda5   VG VolGroup00   lvm2 [55.56 GB / 32.00 MB free]
  PV /dev/hdb3                   lvm2 [196.11 MB]
  Total: 3 [111.26 GB] / in use: 2 [111.07 GB] / in no VG: 1 [196.11 MB]
lvm> vgscan
  Reading all physical volumes.  This may take a while...
  Found volume group "7200rpm" using metadata type lvm2
  Found volume group "VolGroup00" using metadata type lvm2

If you extract the contents of your initrd, you'll probably find in"init" the following lines:


echo Scanning logical volumes
lvm vgscan --ignorelockingfailure
echo Activating logical volumes
lvm vgchange -ay --ignorelockingfailure VolGroup00

You can extract the initrd as follows:

$ cd /tmp
$ mkdir initrd
$ cd initrd
$ gzip -dc < /boot/initrd-2.6.15-1.1948_FC5.img | cpio -i

You might be able to produce a suitable initrd by editing your/etc/fstab (at least temporarily) to point to the right logical volumesand then run mkinitrd to create a new initrd for booting from the new disk.


Paul.