[linux-lvm] root fs on a LVM cause kernel panic

[Andreas Dilger]

On Nov 16, 2001  17:19 -0500, Daniel Savard wrote:
> While booting I am ending with a kernel panic message. The few last lines of
> the boot message are as follow:
> 
> VFS: Cannot open root device "3a01" or 3a:01
> Please append a correct "root=" boot option
> Kernel panic: VFS: Unable to mount root fs on 3a:01

Hmm, you only get that message when the initial boot is done, so two 
possibilities (I'm not an initrd guru, mind you):

1) you need to change the root= line in your lilo.conf to say "root=/dev/ram0"
   so that it will boot into the initrd.  Then do the real-root-dev trick
   (or try pivot_root if running a 2.4 kernel) after configuring the LVM
   stuff via vgscan; vgchange -a y.

2) You didn't re-run lilo after changing lilo.conf (yes, you probably did,
   but you can never tell from here, and always safe to ask).

> I also tested with ramdisk_size=X, where X is the size returned by the
> lvmcreate_initrd script for the ramdisk.

As long as this is larger than the size of the uncompressed ramdisk, you
should be OK.

Cheers, Andreas
--
Andreas Dilger
http://sourceforge.net/projects/ext2resize/
http://www-mddsp.enel.ucalgary.ca/People/adilger/