[linux-lvm] Uuid for unknown device blows up VolGroup00

[linux-lvm] Uuid for unknown device blows up VolGroup00

[Teak Billard]

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Dear all,

I recently tried to add an old 30 GB hard drive lying in my machine to my FC5 system.  I was trying to add the 30 GB to VolGroup00.  I failed somehow and now the entire VolGroup00 is inaccessible.  When booting I get a Kernel panic - not syncing: Attempted to kill init!  I think if I removed the offending Uuid from VolGroup00 things would go back to normal.

Here's the output of some lvm commands from the FC Rescue Disk:

 lvm> pvscan
 Couldn't find device with uuid '8YsyEa-r5Rx-2LLI-Zz7n-xr8s-VksP-Mhs0Wi'
 PV  /dev/hdb3             VG VolGroup00  lvm2  [47.81 GB / 32.00 MB free]
 PV unknown device      VG VolGroup00  lvm2  [27.94 GB / 27.94 GB free]
 Total: 2 / in use: 2 / in no VG: 0
 
 lvm> vgscan
 Couldn't find device with uuid: '8YsyEa-r5Rx-2LLI-Zz7n-xr8s-VksP-Mhs0Wi'.
 Couldn't find all phsyical volumes for volume group VolGroup00
 Couldn't find device with uuid: '8YsyEa-r5Rx-2LLI-Zz7n-xr8s-VksP-Mhs0Wi'.
 Couldn't find all phsyical volumes for volume group VolGroup00
 Volume Group "VolGroup00" not found

When I do an lvm pvdisplay, it reveals that VolGroup00 has two uuid's in it. One is /dev/hdb3 with uuid M3CWKv-a2yK-b5Qu-rLzq-Aj27-lXxE-WzvkWE and the other is unknown device with uuid 8YsyEa-r5RX-2LLI-Zz7n-Xr8s-VksP-Mhs0Wi.


I would greatly appreciate any help.  I'm currently unable to get at my data since it was all in VolGroup00.  Please help me if you can. :)

Teak

 		
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Re: [linux-lvm] Uuid for unknown device blows up VolGroup00

[Dieter Stüken]

Teak Billard wrote:
> I recently tried to add an old 30 GB hard drive lying in my machine to
> my FC5 system.  I was trying to add the 30 GB to VolGroup00.  I failed
> somehow and now the entire VolGroup00 is inaccessible.  When booting I
> get a Kernel panic - not syncing: Attempted to kill init!  I think if I
> removed the offending Uuid from VolGroup00 things would go back to normal.
> ....
> When I do an lvm pvdisplay, it reveals that VolGroup00 has two uuid's in
> it. One is /dev/hdb3 with uuid M3CWKv-a2yK-b5Qu-rLzq-Aj27-lXxE-WzvkWE
> and the other is unknown device with uuid
> 8YsyEa-r5RX-2LLI-Zz7n-Xr8s-VksP-Mhs0Wi.

seems you did NOT fail adding the new disk. Have a look into your 
/etc/lvm/backup/VolGroup00 to find how your VG is composed.

It seems, you succeed in adding the disk, but you finally did
not use it and disconnected it. LVM however has registered
the new disk, even if you did not copy any data to it.

You should reconnect the formerly added disk and unregister
it from your volume group by "vgreduce". If you don't have the
disk any more or used it elsewhere, you may try the option
"vgreduce --removemissing".

> I failed somehow and now ...

can you tell us, why it did not work as you expected?

Dieter.

Re: [linux-lvm] Uuid for unknown device blows up VolGroup00

[Teak Billard]

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Dieter St�ken <stueken@conterra.de> wrote: Teak Billard wrote:
> I recently tried to add an old 30 GB hard drive lying in my machine to
> my FC5 system.  I was trying to add the 30 GB to VolGroup00.  I failed
> somehow and now the entire VolGroup00 is inaccessible.  When booting I
> get a Kernel panic - not syncing: Attempted to kill init!  I think if I
> removed the offending Uuid from VolGroup00 things would go back to normal.
> ....
> When I do an lvm pvdisplay, it reveals that VolGroup00 has two uuid's in
> it. One is /dev/hdb3 with uuid M3CWKv-a2yK-b5Qu-rLzq-Aj27-lXxE-WzvkWE
> and the other is unknown device with uuid
> 8YsyEa-r5RX-2LLI-Zz7n-Xr8s-VksP-Mhs0Wi.

seems you did NOT fail adding the new disk. Have a look into your 
/etc/lvm/backup/VolGroup00 to find how your VG is composed.

It seems, you succeed in adding the disk, but you finally did
not use it and disconnected it. LVM however has registered
the new disk, even if you did not copy any data to it.

You should reconnect the formerly added disk and unregister
it from your volume group by "vgreduce". If you don't have the
disk any more or used it elsewhere, you may try the option
"vgreduce --removemissing".

> I failed somehow and now ...

can you tell us, why it did not work as you expected?

Dieter.

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This is exactly what I did to fix the problem: vgreduce --removemissing VolGroup00.
 
 > can you tell us, why it did not work as you expected?
 
 First time using volume groups.  Installed FC5 back when it came out and didn't really know what I was doing.  Now I do.  After fixing the problem, I got wise, used the lvm commands and added the new hard disk as a physical volume, and merged it into the existing volume group.
 
 I had messed around with the lvm gui beforehand and may have caused a problem then.
 
 In my getting wise period I read that the problem with volume groups is that if one hard drive fails, the entire volume group is finished.  That to me is extremely dangerous.  Am I right to be concerned?
 
 Teak



 		
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Re: [linux-lvm] Uuid for unknown device blows up VolGroup00

[Dieter Stüken]

Teak Billard wrote:
> In my getting wise period I read that the problem with volume groups is
> that if one hard drive fails, the entire volume group is finished.  That
> to me is extremely dangerous.  Am I right to be concerned?

If one hard disk fails, all data on THAT disk has gone.
As long as you have several small LV which completely
fit on a single disk, they are not lost, if some other
disk fails. The advantage of using LVM instead of plain
partitions is, that the LVs have real names instead of
ugly names like "/dev/sdb3", they may be resized and they
may be moved easily between different disks, even while
in use!

If you use LVM to bundle several disks to get bigger LVs
which spread over several disks, you depend on the reliability
of each disk. But this is the price you have to pay for
the plus of flexibility. You may feel saver, to separate
both disk by using separate LVs for each. So if one disk
fails, you saved one half of your data. So is this only
half as worse to loose only one half of your data?

If you work with individual disks and partitions, the
risk of accidentally deleting or formatting the wrong
disk or partition is much higher than with LVM, where
your "partitions" have expressive names. Also the LVM
commands prevent you from accidentally performing
destructive actions.

If your data is important, you have to make backups anyway.
If you worry about your data, you should buy reliable disks
or use a raid5 setup.

Dieter