LVM and grub

Mikkel L. Ellertson mikkel at
Tue Feb 12 17:11:49 UTC 2008

Timothy Murphy wrote:
> I'm using LVM on several computers too.
> My point is that on this particular computer /dev/root was not found
> because LVM was not active at this point;
> and my question was: Is there any way of activating LVM
> (equivalent to "vgchange -a y") either by a grub command,
> or by a kernel option?
> To explain the setup briefly.
> I installed the Fedora-8 KDE Live CD on this computer,
> which was already partitioned with LVM
> (except for /boot which was a normal primary partition).
> I could do this because although the Live CD
> did not see the LVM partitions
> I could activate them (as above)
> and then click on the "Install on Hard Disk" button.
> But the resulting system did not boot, as explained above,
> and I found no way to boot it,
> eg through the Rescue CD,
> or by running grub interactively.
> It seems to me that grub was confused in some way
> by the installation.
> However, I'm pretty sure it would have worked
> had I been able to activate LVM.
> As I mentioned, the matter is historical,
> as I deleted the LVM partitions, created normal ones
> and then install the KDE Live CD,
> and the resulting system is working fine,
> after 250 update packages.
Grub does not understand LVM at all. This is why you normally have a 
separate /boot partition when using LVM. Everything Grub needs is on 
the /boot partition. Once Grub loads the kernel, and initrd (if 
used), it turns control over to the kernel. In the case of LVM, the 
code to process the LVM volume group is in the initrd.

It was not Grub that was confused. If it was, then the kernel and 
initrd would not have been loaded. But it sounds like the initrd was 
not built properly. This may have been because of the way you did 
the install. It is hard to say now. I can think of a couple of ways 
that may have fixed the problem, but I guess it does not matter now, 
as we have no way to test them.


   Do not meddle in the affairs of dragons,
for thou art crunchy and taste good with Ketchup!

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