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[SOLVED] rootdevice "fc03" or unknown-block(252,3): error -6
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guid0
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PostPosted: Sat Mar 09, 2013 9:29 pm    Post subject: [SOLVED] rootdevice "fc03" or unknown-block(252,3) Reply with quote

-blam i cannot even boot the machine-

FULL ERRORMESSAGE:
Quote:
VFS: Cannot open rootdevice "fc03" or unknown-block(252,3): error -6


Im trying to restore a bare-metal gentoo setup into a kvm-vm (one of many) in a sort of stage4 way. I have full OS in tarbal and a gentoo bootcdrom.

I have set the usual kernelfeatures:

Code:
CONFIG_VIRT_TO_BUS=y
CONFIG_VIRTIO_BLK=y
CONFIG_VIRTIO_NET=y
CONFIG_VIRTIO_CONSOLE=y

Code:
CONFIG_BLK_DEV_BSG=y
CONFIG_BLK_DEV=y
CONFIG_DEVTMPFS=y
CONFIG_DEVTMPFS_MOUNT=y

adjusted some files

Code:
/etc/fstab


even regenerated

Code:
/etc/mtab


en tried lilo several times in a repeating process.

Code:
livecd ~ # chroot /mnt/gentoo/

Code:
cat /etc/lilo.conf

Quote:
lba32
boot=/dev/vda
disk=/dev/vda bios=0x80 max-partitions=7

map = /boot/.map
install = /boot/boot-menu.b
menu-scheme=Wb
prompt
timeout=80
delay = 50
image = /boot/vmlinuz-3.8.1
root = /dev/vda3
label = 3.8.1
read-only

Code:
livecd / # lilo

Quote:
Warning: /proc/partitions references Experimental major device 252.
Warning: /proc/partitions references Experimental major device 252.
Warning: /proc/partitions references Experimental major device 252.
Warning: /proc/partitions references Experimental major device 252.
Added 3.8.1 *
4 warnings were issued.


However,.. on umount and reboot from virtual disk i get at around 5seconds of kernel-time:

Quote:
VFS: Cannot open rootdevice "fc03" or unknown-block(252,3): error -6


Now here is what is weird. The Gentoo install-amd64-minimal-20130110.iso CD boots the environment with the following devices:
[*]LIVECD
Quote:
livecd / # ls -laF /dev/vda*
brw-rw---- 1 root disk 252, 0 Mar 9 22:07 /dev/vda
brw-rw---- 1 root disk 252, 1 Mar 9 15:44 /dev/vda1
brw-rw---- 1 root disk 252, 2 Mar 9 15:44 /dev/vda2
brw-rw---- 1 root disk 252, 3 Mar 9 15:44 /dev/vda3
etc


[*]OTHER VIRT MACHINE
Quote:
machine / # ls -laF /dev/vda*
brw-rw---- 1 root disk 254, 0 Mar 9 22:07 /dev/vda
brw-rw---- 1 root disk 254, 1 Mar 9 15:44 /dev/vda1
brw-rw---- 1 root disk 254, 2 Mar 9 15:44 /dev/vda2
brw-rw---- 1 root disk 254, 3 Mar 9 15:44 /dev/vda3
etc


So this currently leaves me with either unsupported vanilla-kernel installcd combination or mknod adjustable things to try.. unless this is a BUG EATING MY SHOE 8)

Anyways, I would like to end debugging this process more quickly and kindly ask for any hint whatsoever whilst i try my last options. ;)

Cheers,
guid0


Last edited by guid0 on Sun Mar 10, 2013 11:10 am; edited 1 time in total
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guid0
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PostPosted: Sat Mar 09, 2013 9:37 pm    Post subject: Reply with quote

indeed,.. as i already figured.. below does not help.
Code:

livecd ~ # rm /dev/vda2
rm: remove block special file '/dev/vda2'? y
livecd ~ # rm /dev/vda4
rm: cannot remove '/dev/vda4': No such file or directory
livecd ~ # rm /dev/vda3
rm: remove block special file '/dev/vda3'? y   
livecd ~ # rm /dev/vda
rm: remove block special file '/dev/vda'? y
livecd ~ # mknod -m 660 /dev/vda3 b 254 3
livecd ~ # mknod -m 660 /dev/vda2 b 254 2
livecd ~ # mknod -m 660 /dev/vda1 b 254 1
livecd ~ # mknod -m 660 /dev/vda b 254 0
livecd ~ # chown root:disk /dev/vda*
livecd ~ # mount /dev/vda3 /mnt/gentoo/
mount: /dev/vda3 is not a valid block device


too tired to tinker with other kernels..
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Ant P.
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PostPosted: Sat Mar 09, 2013 10:26 pm    Post subject: Reply with quote

Last time I tried, the only thing that booted reliably with a virtio disk was grub2.
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guid0
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PostPosted: Sat Mar 09, 2013 10:27 pm    Post subject: Reply with quote

Ant P. wrote:
Last time I tried, the only thing that booted reliably with a virtio disk was grub2.

thing is, i have shedloads of virtual machines running lilo with that exact same config file. using grub/grub2 for this one pushes system administration in an awkward direction. id like to hold that off for a bit..
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NeddySeagoon
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PostPosted: Sat Mar 09, 2013 10:59 pm    Post subject: Reply with quote

guid0,

I use grub1 on my KVMs. I run LVM on the underlying hardware and they all get a logical volume for disk space, which is further partitioned inside the KVM.

At face value
Code:
unknown-block(252,3)
says the volume was found but the filesystem there cannot be read.
Given that you have stage4ed the VM, thats exceedingly unlikely
_________________
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NeddySeagoon

Computer users fall into two groups:-
those that do backups
those that have never had a hard drive fail.
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guid0
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PostPosted: Sun Mar 10, 2013 7:45 am    Post subject: Reply with quote

Thanks again for your response NeddySeagoon your almost 30k posts are impressive. 8O
I wonder if this procedure is borked because the original system from which the stage4 is snapped is running a software raid1 setup.
Cant really imagine why though...

guid0
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guid0
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PostPosted: Sun Mar 10, 2013 8:09 am    Post subject: Reply with quote

Here we go..
Code:

[ebuild  N     ] sys-boot/grub-0.97-r12  USE="-custom-cflags -ncurses -netboot -static" 1,034 kB

/boot/grub/grub.conf:
Code:

default 0
timeout 30
splashimage=(hd0,0)/boot/grub/splash.xpm.gz

title Gentoo Linux 3.8.1
root (hd0,0)
kernel /boot/vmlinuz-3.8.1 root=/dev/vda3

but another fail..
Code:

Probing devices to guess BIOS drives. This may take a long time.

    GNU GRUB  version 0.97  (640K lower / 9216K upper memory)

 [ Minimal BASH-like line editing is supported.  For the first word, TAB
   lists possible command completions.  Anywhere else TAB lists the possible
   completions of a device/filename. ]
grub> root (hd0,0)
root (hd0,0)

Error 21: Selected disk does not exist


:(
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guid0
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PostPosted: Sun Mar 10, 2013 8:41 am    Post subject: Reply with quote

same issue using an ubuntu-server install iso. im kinda lost here..
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guid0
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PostPosted: Sun Mar 10, 2013 9:10 am    Post subject: Reply with quote

Fixed using
Quote:
grub> device (hd0) /dev/vda
device (hd0) /dev/vda
grub> root (hd0,0)
root (hd0,0)
Filesystem type is ext2fs, partition type 0x83
grub> setup (hd0)
setup (hd0)
Checking if "/boot/grub/stage1" exists... yes
Checking if "/boot/grub/stage2" exists... yes
Checking if "/boot/grub/e2fs_stage1_5" exists... yes
Running "embed /boot/grub/e2fs_stage1_5 (hd0)"... 22 sectors are embedded.
succeeded
Running "install /boot/grub/stage1 (hd0) (hd0)1+22 p (hd0,0)/boot/grub/stage2 /boot/grub/menu.lst"... succeeded
Done.


At least the system boots now.. will solve as soon as lilo works again ;)
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guid0
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PostPosted: Sun Mar 10, 2013 11:09 am    Post subject: Reply with quote

fixed using grub to boot and managed to switch back to lilo using below command 8)

Code:

machine734 ~ # lilo
Warning: /proc/partitions references Experimental major device 254.
Warning: /proc/partitions references Experimental major device 254.
Warning: /proc/partitions references Experimental major device 254.
Warning: /proc/partitions references Experimental major device 254.
Added 3.8.1 *
4 warnings were issued.

Code:

reboot

yay!
guid0
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NeddySeagoon
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PostPosted: Sun Mar 10, 2013 4:08 pm    Post subject: Reply with quote

guid0,

OK, ... but why?
_________________
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NeddySeagoon

Computer users fall into two groups:-
those that do backups
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guid0
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PostPosted: Sun Mar 10, 2013 4:58 pm    Post subject: Reply with quote

guid0 wrote:
thing is, i have shedloads of virtual machines running lilo with that exact same config file. using grub/grub2 for this one pushes system administration in an awkward direction. id like to hold that off for a bit..

fixing 1 system with lilo literally saves me weeks of work and reboots to ensure grub/grub2 works as expected. :wink:
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NeddySeagoon
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PostPosted: Sun Mar 10, 2013 5:45 pm    Post subject: Reply with quote

guid0,

I intended you to speculate on why installing grub allowed lilo to work?
It smacks of clock skew but I can't really explain it.
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NeddySeagoon

Computer users fall into two groups:-
those that do backups
those that have never had a hard drive fail.
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guid0
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PostPosted: Sun Mar 10, 2013 7:38 pm    Post subject: Reply with quote

I can only guess at it. It surely wasnt a clock skew. I have been bitten by the clock several times before and its something I checked.

I tried stracing lilo but that wasnt really helpful either. The only thing I can currently think of is that the original setup was created many many years ago (somewhere 2005). I went through several update cycles and may have run a 2.4 kernel if not an early 2.6 tree before moving into 3.x which was done only recently.

Perhaps lilo left some map files around that were somewhat stoneaged. I really dont know. Grub didnt do it either until i provided the device (hd0) /dev/vda line. Manually updating the devices.map in grub turned out to be useless.

guid0
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NeddySeagoon
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PostPosted: Sun Mar 10, 2013 7:49 pm    Post subject: Reply with quote

guid0,

I installed my KVMs using emulated hardware, so grub did not have issues like that and switched to virtio hardware later.
In fact, I only ever installed one very basic KVM and cloned it everywhere, then added to the clones.
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NeddySeagoon

Computer users fall into two groups:-
those that do backups
those that have never had a hard drive fail.
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