Robert L Cochran wrote:
Jim Cornette wrote:
Robert L Cochran wrote:
Jim Cornette wrote:
Robert L Cochran wrote:
https://www.redhat.com/archives/fedora-list/2005-April/msg01943.html
From an earlier posting someone suggested to run the following
commands to activate and later deactivate LVM volumes in rescue
mode. I used these commands on an external USB drive to get at
data from a previous installation and it worked. You might be
able to get at your data in this way.
Jim
lvm lvscan
lvm vgchange -ay
I'd like to follow up on this. Here is what I did.
1. Booted machine in rescue mode, using my install DVD, with the
external USB drive containing my other FC4 system plugged in.
I booted into my regular installation. I then ran 'lvm vgchange -ay'
to activate the lvm volumes. I think that I did a pvscan to get the
information about the available lvms.
2. Executed 'chroot /mnt/sysimage'.
This would simple activate your system without all of the normally
loaded tools. This is good information for if you needed to mount
your system in rescue mode in the future.
3. Ran 'lvm lvscan' as suggested. I got this output.
ACTIVE 'dev/VolGroup00/LogVol00' [370.53 GB] inherit
ACTIVE 'dev/VolGroup00/LogVol01' [1.94 GB] inherit
The above logical volumes seem to reference my 400 Gb hard drive in
my new, upgraded system, not the 60 Gb drive which is connected by USB.
The 'vgchange -ay' command might be needed to add additional volumes
that might have labelling which conflict with your newly mounted system.
lvscan might then recognize the volumes on the USB enclosure drive.
I then unplugged the USB cable for my 60 Gb drive and re-plugged it
in. Executing 'lvm lvscan' then got me this output:
/dev/sdb1: open failed: no such device or address
/dev/sdb2: open failed: no such device or address
/dev/sdb3: open failed: no such device or address
/dev/sdb3 seems to be where your LVM is located.
ACTIVE 'dev/VolGroup00/LogVol00' [370.53 GB] inherit
ACTIVE 'dev/VolGroup00/LogVol01' [1.94 GB] inherit
Question: should I have manually mounted the partitions before
issuing 'lvm lvscan'?
I am not sure if it is possible to mount a partition with lvm volumes
on it. I would imagine that filesystem is not correct would result
from attempting to mount /dev/sdb3.
************ (Removed rescue CD, boot back into Fedora Core 4 on new
system) ************
I then read the entire LVM how-to for lvm2 on tldp.org. It doesn't
offer practical advice for this situation -- rescuing data from an
older lvm-based system.
Go figure, real life situations never seem to match intended use for
systm designs.
I also read 'man lvm', with no better results.
I then checked Bugzilla. There are 124 (or is it 125?) bugs listed
for LVM.
It is looking more and more like I'll need to take out my 400 Gb
drive and substitute my 60 Gb drive/120 Gb drive, and boot into that
system, all to recover a little more data. Perhaps I need to quit
using LVM.
Not adding a detour to those that use LVM, but adding a "me too" to
LVM usage.
If you do have to take drastic measures and re-install the drive from
the USB enclosure, add this fact to the list. I did get this to work
for once and recovered data from the drive contained in the USB
enclosure. I really don't recall the exact steps that I took to get
at the drive. It mounted and I did retrieve the information from the
drive.
Since you have LVMs on your new system also, probably the
dev/VolGroup00/LogVol00 identity is the same for both disks. It might
have worked for me because I had no new LVMs on the running system.
Give system-config-lvm a try and see if you can manipulate the USB
drive on a running system. If not, you may be out of luck and need to
swap the drive out and backup your desired information onto a DVD or
other media.
I'm sure the information is on the LVM, but in what format, I don't
know. (dev/VolGroup00/LogVol00 also or different)
Jim
Thanks
Bob Cochran
To continue the saga, I took my machine apart to investigate this and
spent part of the evening swapping drives in and out. I really feel
like I'm paying big for not understanding how LVM works -- and
remaining in blissful ignorance for a couple of years, too.
Too bad Filipe is not active on the list. He seemed to know pretty much
about it. I should become more familiar with the workings of LVM also.
However, I deserted the concept and went with traditional partitioning.
My Asrock motherboard has an option for booting from USB, so I tried
to boot my 60 Gb drive from USB (in order to avoid taking it out of
the external enclosure.) This gave me a black screen with these letters:
LI
USB support for drives was not setup in Fedora/Redhat yet. There has to
be USB drivers added to the initrd before it will boot. With USB support
in BIOS, you are OK until the kernel takes over from BIOS. After the
kernel starts to search for drives, no drives are found because of the
chicken or egg syndrome. USB devices are needed before the USB drives
are detected.
I have some memory that this is the word LINUX and how many letters of
the word are spelled out on the screen indicate something about the
nature of the boot problem. No doubt, to boot from USB, I need code
that can speak USB-ese. So much for this option.
I took the drive out of the enclosure, and connected it to the
motherboard's SATA connector (There are 3, and I used the one numbered
SATA1.) I When I turned on the power, the exprected GRUB screen came
up, and when I booted the 1653 kernel, a kernel panic resulted. I got
this message:
Unable to find volume group "VolGroup00"
Do you have all the drives in the computer, the new system and the drive
from the USB enclosure?
I am not sure what your actual setup is.
Rescue discs are starting to sound appropriate now.
So now I'm confused. It looks to me like Grub is installed on my 60 Gb
drive (that's why I got the nice splash screen) but the actual volume
group is defined on my 120 Gb drive? This 120 Gb physical drive is (or
was) really an older system. I thought I had one system installed on
each of two different drives. I thought the 60 Gb drive was devoted
to Fedora Core 4 and the 120 Gb drive was an older release, Fedora
Core 3.
With the LABEL and the way different BIOS versions work, it is easy to
become confused on what device is the actual booting device.
Bob Cochran
--
Good leaders being scarce, following yourself is allowed.
