Unable to boot due to changes in fstab

Covel · 02-03-2004, 01:57 PM

Hi!

I configured and compiled kernel 2.6.1 following the README file and the compiling kernel how-to for newbies . Everything went fine.

But when I tried to boot with 2.6.1 I was getting this error:

Code:

VFS: Cannot open root device "LABEL=/" or unknown-block(0,0)

followed by kernel panic

I searched the internet do find the solution to this problem and I found out that this looks like a common problem. I tried to follow a solution I found and now I cannot boot with any kernel.

What did I do:

I made a backup of the file /etc/fstab and edited to change the line

Code:

LABEL=/    /    1    1

to

Code:

/dev/hd1   /   1   1

following the suggestion I found to solve my problem.

I also changed grub.conf to fit this change in fstab.

Now, when I try to boot with kernel 2.6.1 I get

Code:

VFS: Cannot open root device "root=/" or unknown-block(0,0)

Booting with the previous bootable kernel I get and error about not being able to mount my filesystem. It asks me for the root password to give me a shell do try to correct my problem but the access to the file system is read-only and I cannot change back th fstab file.

I tried the Red Hat disk and

boot: linux rescue

to get a read.write shell but an error occurs trying to mount the file system and only part of it is mounted.... and fstab isn't in that part

So what else can I do to fix this? Any ideas?

This is on Red Hat 9.0

g-rod · 02-03-2004, 02:07 PM

It is not /dev/hd1 but /dev/hda1 or /dev/hda2 or /dev/hdb1. It all depends on how your hard drive is configured. Boot using you old kernel or a rescue disk and post the output of mount if you still cannot get it to work. You are problably going to need to run fsck once you get this straightened out.

Covel · 02-07-2004, 09:46 AM

This is what I get at startup:

Quote:

Checking root filesystem

The superblock could not be read or does not describe a correct ext2 filesystem. If the device is valid and it really contains an ext2 filesystem (and not swap or ufs or something else), then the superblock is corrupt and you might try running e2fsck with an alternate superblock

e2fsck -b 8193

fsck.ext3: bad magic number in superblock while trying to open /dev/hda1

And according to my previous fstab I think my root partition should be hdb2 and not hda1.

Quote:

(...)
/dev/hdb3 swap swap defaults 0 0
/dev/fd0 /mnt/floppy auto noauto,owner,kudzu 0 0
/dev/hda6 /data vfat auto,owner,gid=users,umask=0002,exec,rw 0 0
(...)

That /data is located on another disk. and as you can see, my swap partition is in /dev/hdb3! That's why I think my root partition should be in b too!

Am I right?

Covel · 02-07-2004, 11:09 AM

AH! It's now working

I use that read-only shell and ran:

mount -o remount,rw /dev/hdb2

to make it read-write. /dev/hdb2 is where I guessed my root partition would be.
Then I changed this line of fstab:

/dev/hda1 / 1 1

(that was LABEL=/ before all this happen)

to

Code:

/dev/hdb2   /   1   1

Then I edited grub.conf to make kernel 2.6.1 use the root partition at /dev/hdb2 insted of LABEL=/

Code:

kernel /vmlinuz-2.6.1-03.02.04 ro root=/dev/hdb2 hdc=ide-scsi

Reboot!

Now I only have a problem with loading modules but booting is fine

T3RM1NVT0R · 12-09-2010, 04:18 PM

Hi Covel,

Thanks a lot... I was facing the same issue. Your trick did the job.

Thanks & Regards,

T3RM1NVT0R