[SOLVED] Empty /dev directory, GRUB error 15

ravicious · 2011-08-22 00:01:31

So I've moved some partitions (as shown in this screenshot) and everything looks fine, I can access all my data from Arch partitions just by using LiveCD. However, my /dev directory is empty (it contains `console`, `null` and `zero` files only) and (because of this) Arch won't boot, because grub can't find the kernel image. What should I do now?

Last edited by ravicious (2011-08-22 09:33:46)

falconindy · 2011-08-22 00:14:13

Grub not being able to find the kernel is completely separate from /dev not being mounted (and thus being unpopulated). Fix your bootloader config to point at the right disk/file.

ravicious · 2011-08-22 00:38:31

Well, I have only three partitions for Arch: / (root), /home and /boot. When I use LiveCD and browse root, isn't /dev supposed to be populated?

Anyway, here's how the situation looks:

fdisk -l before messing with partitions (messages are in Polish, but it shouldn't be a problem):

~ $ sudo fdisk -l
Hasło:

Dysk /dev/sda: 320.1 GB, bajtów: 320072933376
głowic: 255, sektorów/ścieżkę: 63, cylindrów: 38913, w sumie sektorów: 625142448
Jednostka = sektorów, czyli 1 * 512 = 512 bajtów
Rozmiar sektora (logiczny/fizyczny) w bajtach: 512 / 512
Rozmiar we/wy (minimalny/optymalny) w bajtach: 512 / 512
Identyfikator dysku: 0xaad13451

Urządzenie Rozruch   Początek      Koniec   Bloków   ID  System
/dev/sda1   *          63      401624      200781    7  HPFS/NTFS/exFAT
/dev/sda2          417690   105277325    52429818    7  HPFS/NTFS/exFAT
/dev/sda3       105290071   594198527   244454228+   f  W95 Rozsz. (LBA)
/dev/sda4       594199552   625142447    15471448   12  Compaq diagnostics
/dev/sda5       517100220   594198527    38549154    7  HPFS/NTFS/exFAT
/dev/sda6       105290073   165276719    29993323+  83  Linux
/dev/sda7       165276783   165533759      128488+  83  Linux
/dev/sda8       165533823   517100219   175783198+  83  Linux

Wpisy w tablicy partycji nie są w tej kolejności, co na dysku

fdisk -l after messing with partitions:

ubuntu@ubuntu:~$ sudo fdisk -l

Disk /dev/sda: 320.1 GB, 320072933376 bytes
255 heads, 63 sectors/track, 38913 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Disk identifier: 0xaad13451

   Device Boot      Start         End      Blocks   Id  System
/dev/sda1   *           1          25      200781    7  HPFS/NTFS
/dev/sda2              27        6554    52429818    7  HPFS/NTFS
/dev/sda3            8480       38913   244461105    f  W95 Ext'd (LBA)
/dev/sda5            8481       12214    29993355   83  Linux
/dev/sda6           12215       12230      128488+  83  Linux
/dev/sda7           12231       38913   214331169   83  Linux

According to this, I've changed /boot/grub/menu.lst and /etc/fstab. Here's how menu.lst looks like:

# general configuration:
timeout   5
default   0
color light-blue/black light-cyan/blue

# (0) Arch Linux
title  Arch Linux
root   (hd0,4)
kernel /vmlinuz-linux root=/dev/sda6 ro
initrd /initramfs-linux.img

# (1) Arch Linux
title  Arch Linux Fallback
root   (hd0,4)
kernel /vmlinuz-linux root=/dev/sda6 ro
initrd /initramfs-linux-fallback.img

# (2) Windows
title Windows 7
rootnoverify (hd0,0)
makeactive
chainloader +1

(hd0,4) should point to /dev/sda5 (well, there's root partition) and /dev/sda6 points to /boot, so I think I didn't make any mistake here.

Here's fstab:

devpts                 /dev/pts      devpts    defaults            0      0
shm                    /dev/shm      tmpfs     nodev,nosuid        0      0

/dev/sda5 / ext4 defaults 0 1
/dev/sda6 /boot ext4 defaults 0 1
/dev/sda7 /home ext4 defaults,user_xattr 0 1
/dev/sda2 /mnt/windows ntfs-3g gid=users,fmask=113,dmask=002 0 0

I hope this explains my situation a bit more clearly.

Last edited by ravicious (2011-08-22 00:44:42)

falconindy · 2011-08-22 00:55:24

ravicious wrote:

When I use LiveCD and browse root, isn't /dev supposed to be populated?

/dev should be mounted for the live environment. Unless you decided to mount another instance on devtmpfs on /path/to/arch-install/dev, I'm not sure why you'd expect it to be there.

Seems that you've physically moved the /boot partition on the disk. You'll probably need to reinstall grub to the MBR to make sure it knows how to get to /boot and /.

Last edited by falconindy (2011-08-22 00:55:39)

ravicious · 2011-08-22 01:04:44

falconindy wrote:

Seems that you've physically moved the /boot partition on the disk. You'll probably need to reinstall grub to the MBR to make sure it knows how to get to /boot and /.

So all I have to do now is to run `grub-install /dev/sda` as a root, right? Is it safe to do this right now? My memories with installing grub to the mbr are quite bad... At this moment it's rather impossible for me to do a full system backup, I have only my media backed up on my other computer, losing my current Arch installation would be pretty painful.

Last edited by ravicious (2011-08-22 01:05:07)

falconindy · 2011-08-22 01:16:16

You'd want to ignore the current device map as well and make sure to target the right root directory... It's been a while, but if my memory serves me:

grub-install --root-directory=/path/to/arch-install --recheck /dev/sda

Of course, make sure /boot is mounted in the right place as well.

ravicious · 2011-08-22 08:52:08

grub is working, here's what I have done, step by step:

Mounted /boot partition at /media/boot

Ran grub-install:

grub-install --root-directory=/media/boot --recheck /dev/sda

grub created a boot directory under /media/boot/boot, so I ran grub-install once again:
```
grub-install --root-directory=/media --recheck /dev/sda
```
Rebooted my laptop

Window boots without any problems, booting to Arch gives me error 15. I'll try to figure something out, but I don't see what could possibly be wrong.

BTW, now I see that I could simply do this:

mount /dev/sda5 /mnt/main
mount /dev/sda6 /mnt/main/boot
grub-install --root-directory=/mnt/main /dev/sda

Is it diffrent from having /boot under /media/boot?

Edit:

I'll try to reinstall grub using command from the second method.

Edit2:

Apparently I had to change my menu.lst file to something like this:

# (0) Arch Linux
title  Arch Linux
root   (hd0,5)
kernel /vmlinuz-linux root=/dev/sda5 ro
initrd /initramfs-linux.img

Just to remember: `root` should point to /boot partition, `kernel [...] root=` should point to / (root).

Last edited by ravicious (2011-08-22 09:38:54)

Arch Linux

#1 2011-08-22 00:01:31

[SOLVED] Empty /dev directory, GRUB error 15

#2 2011-08-22 00:14:13

Re: [SOLVED] Empty /dev directory, GRUB error 15

#3 2011-08-22 00:38:31

Re: [SOLVED] Empty /dev directory, GRUB error 15

#4 2011-08-22 00:55:24

Re: [SOLVED] Empty /dev directory, GRUB error 15

#5 2011-08-22 01:04:44

Re: [SOLVED] Empty /dev directory, GRUB error 15

#6 2011-08-22 01:16:16

Re: [SOLVED] Empty /dev directory, GRUB error 15

#7 2011-08-22 08:52:08

Re: [SOLVED] Empty /dev directory, GRUB error 15

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