[SOLVED] Root fs cannot be found on boot (initramfs works)

Question

Hi all! Long time lurker, first time poster.
I'd been using catalyst drivers since I started out on Arch. I knew there were conflicts during updates involving catalyst, so I've never updated my kernel or Xorg during "pacman -Syu" updates. I'd specifically blocked them in pacman.conf. However, I recently decided to switch to open source ati drivers and in doing so, decided to update my entire system including the kernel. Everything went smoothly, but upon reboot I'm getting the dreaded "root filesystem cannot be found" error.
Root device '/dev/sdb6' doesn't exist, attempting to create it
ERROR: Failed to parse block device name for '/dev/sdb6' unknown
ERROR: Unable to create/detect root device, '/dev/sdb6'
Dropping to recovery shell.. type 'exit' to reboot
Note that the initramfs worked, it's just it couldn't get into my root partition even though I can mount it without any problems from the live CD.
I set about trying to fix my problem. Here is a list of things I've tried.
1) Using the liveCD, I chrooted into my install (mounting proc, dev, etc. in the process) and did
depmod -a
followed by
pacman -Sf kernel26
which completed with no errors problems. This didn't solve my issue.
2) Using the liveCD, performing
mkinitcpio -M
and ensuring my mkinitcpio.conf file contained all the listed modules. I then rebuilt the initramfs with another
pacman -Sf kernel26
This didn't solve my issue.
3) Playing with grub, replacing my UUID lookups with /dev/sdb6. I also tried different combinations (see this thread) to check the bios and grub were matching up. I did the suggested rootdelay=8 and rootfstype=ext3 stuff, too. This didn't solve my issue.
4) Using the liveCD, I did another depmod -a then downgraded my kernel to the older package found on the 2008.6 CD. Mkinitcpio completed successfully, everything seemed fine, but... This didn't solve my issue.
I've done these steps over and over again in various orders, trying different combinations, but I've not had any luck.
Here is my current mkinitcpio.conf file:
MODULES="pata_acpi pata_jmicron ata_generic scsi_mod ahci ata_piix ext3 ahci libata cdrom ide-core ide-pci-generic jmicron ieee1394 ohci1394 atl1 mii sr_mod usbcore ehci-hcd uhci-hcd jbd"
BINARIES=""
FILES=""
HOOKS="base udev autodetect pata scsi sata usb net usbinput keymap encrypt filesystems"
Here is the important bit of my grub file:
Without UUIDs:
title Arch Linux
root (hd1,5)
kernel /vmlinuz26 root=/dev/sdb6 quiet vga=869 rootdelay=8 rootfstype=ext3
initrd /boot/kernel26.img
title Arch Linux (fallback)
root (hd1,5)
kernel /vmlinuz26 root=/dev/sdb6 ro quiet vga=869 rootdelay=8
initrd /boot/kernel26-fallback.img
With UUIDs:
title Arch Linux
uuid ec450c30-5197-4330-9831-914eafad66ce
kernel /vmlinuz26 root=/dev/disk/by-uuid/ec450c30-5197-4330-9831-914eafad66ce ro quiet vga=869
initrd /boot/kernel26.img
title Arch Linux (fallback)
uuid ec450c30-5197-4330-9831-914eafad66ce
kernel /vmlinuz26 root=/dev/disk/by-uuid/ec450c30-5197-4330-9831-914eafad66ce ro quiet vga=869
initrd /boot/kernel26-fallback.img
Any ideas, help, suggestions, fixes, etc would be greatly appreciated. I just felt like my arch install was damn near perfect - I'd hate to have to install everything again!
(Edit: Just fixing something I'd messed up in my attempts to fix it, as kindly pointed out by Karol. It didn't fix the problem, though.)
Last edited by binarymonster (2009-06-04 10:03:19)

Answer 1

karol wrote:
If you've read http://bbs.archlinux.org/viewtopic.php?id=63033 I assume you've tried to use 'root=/dev/sdb6' w/
root            (hd0,5)
instead of
root            (hd1,5)
but didn't work, right?
This one's old (and odd) but you may want to have a look at it anyway http://bbs.archlinux.org/viewtopic.php?pid=376939
And the very bottom of http://bbs.archlinux.org/viewtopic.php?id=44921
I read that first link - though I might have misinterpreted it. I tried keeping (hd1,5) the same and changing /dev/sdb6 to /dev/sda6, etc. I always through that the grub root (hd0,5) wasn't correct, the initramfs would not be able to show up and I'd just get a grub error. What I have tried so far hasn't worked, but I might try changing to (hd0,5) instead of (hd1,5) in a little while.
With regards to the other links, they seem to suggested lots of things I've already tried. The list is getting quite long now!
I have tried reinstalling kernel26, downgrading kernel26, using the fallback image, made sure mkinitcpio.conf contains my filesystem type, made sure mkinitcpio.conf contains my hdd controller module, tried rootdelay=8 a few times... and my mkinitcpio seems to work, so I don't think the problem is with my mkinitcpio.conf file.
Phew! Thanks for your continued help... I'm sure this problem will get solved eventually (and I bet it'll be something simple!). At least I'm learning about chrooting, initramfs, etc.
Do you think it's worth trying to change root (hd1,5) to (hd0,5)? I imagine that would only cause grub to give me and error and not even be able to find the initramfs!