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#1 2013-09-11 23:03:12

STUART
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From: Seattle, WA
Registered: 2010-08-19
Posts: 42
Website

[SOLVED] grub "unknown filesystem" error for big partition layout

Last night / this morning I copied the root and swap partitions of an Arch Linux installation (stushiba) I had on an old Toshiba hard drive, as well as the "system reserved" and other partitions of a Windows 8 install (stuzate) on another 500GB hard drive, onto a new 2TB Western Digital hard drive using Gparted via an external Arch environment I run off of a microSD card + adapter (sturling).

After doing so, I installed GRUB to the new drive to the best of my ability, but when I try to boot the system with just that drive, this is what I see:

GRUB loading.
Welcome to GRUB!

error: unknown filesystem.
Entering rescue mode...
grub rescue>

Running ls doesn't find anything:

grub rescue> ls
(hd0) (hd0,msdos4) (hd0,msdos3) (hd0,msdos2) (hd0,msdos1)
grub rescue> ls (hd0,msdos4)
(hd0,msdos4): Filesystem is unknown.
grub rescue> ls (hd0,msdos3)
(hd0,msdos3): Filesystem is unknown.
grub rescue> ls (hd0,msdos2)
(hd0,msdos2): Filesystem is unknown.
grub rescue> ls (hd0,msdos1)
(hd0,msdos1): Filesystem is unknown.

The system should be on (hd0,msdos3) - it's ext4, and, if I insert the old Toshiba hard disk to the system and select that as my boot device in BIOS, it boots from the partition on the old drive's grub menu, into the partition in the new drive (because they have the same UUID), so the partition's definitely readable/bootable. (I've tried both regenerating the grub menu and installing grub from this boot scenario, with no change.)

(That said, if I enter a console on my system with a working GRUB installation and do an ls on that partition, I get more "unrecognized filesystem" messages.)

Once the new partition had loaded, I ran

sudo grub-mkconfig -o /boot/grub/grub.cfg

and rebooted, but GRUB was still broken.

I tried fixing this by rebooting into the latest installation media, with only the new hard drive plugged in, and running

mount /dev/sda3 /mnt
arch-chroot /mnt
modprobe dm-mod
grub-install --recheck /dev/sda

But that still hasn't fixed anything: I still get the "error: unknown filesystem." message whenever I try to do anything in GRUB.

My /boot/grub/grub.cfg: http://sprunge.us/RMeD

Help!

Last edited by STUART (2013-09-12 01:55:16)

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#2 2013-09-11 23:31:26

cfr
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From: Cymru
Registered: 2011-11-27
Posts: 6,104

Re: [SOLVED] grub "unknown filesystem" error for big partition layout

Please post the output of lsblk -f and of fdisk -l /dev/sdX where X is the appropriate drive letter e.g. /dev/sda if that is the new disk.


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#3 2013-09-11 23:41:45

STUART
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From: Seattle, WA
Registered: 2010-08-19
Posts: 42
Website

Re: [SOLVED] grub "unknown filesystem" error for big partition layout

This is the output when running from sturling (neither partition booted).

/dev/sda is the new disk, /dev/sdb is the microSD card I'm running the system off of, and /dev/sdc is the old disk.

[stuart@sturling ~]$ sudo lsblk -f
NAME   FSTYPE LABEL           UUID                                 MOUNTPOINT
sda                                                                
├─sda1 ntfs   System Reserved F24C78CE4C788EDB                     
├─sda2 ntfs                   F68C7D338C7CF00B                     
├─sda3 ext4   stushiba        1c8533ed-4a3c-4a4c-907b-682bd2313492 
└─sda4 swap                   97c30b3e-f763-437b-aa71-0378bef4c017 
sdb                                                                
├─sdb1 vfat   savfat          A13A-D130                            /vfat
└─sdb2 ext4   saroot          7434b70f-7028-4a8d-ad78-a4975a98e1a6 /
sdc                                                                
├─sdc1 ext4   stushiba        1c8533ed-4a3c-4a4c-907b-682bd2313492 
└─sdc2 swap                   97c30b3e-f763-437b-aa71-0378bef4c017 
sr0                                                                
[stuart@sturling ~]$ sudo fdisk -l /dev/sda

Disk /dev/sda: 2000.4 GB, 2000365289472 bytes, 3906963456 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk label type: dos
Disk identifier: 0x0005f107

   Device Boot      Start         End      Blocks   Id  System
/dev/sda1            2048      718847      358400    7  HPFS/NTFS/exFAT
/dev/sda2          718848  1937063935   968172544    7  HPFS/NTFS/exFAT
/dev/sda3      1937063936  3873409023   968172544   83  Linux
/dev/sda4      3873409024  3906963455    16777216   82  Linux swap / Solaris
[stuart@sturling ~]$ sudo fdisk -l /dev/sdb

Disk /dev/sdb: 31.9 GB, 31914983424 bytes, 62333952 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk label type: dos
Disk identifier: 0x000c314b

   Device Boot      Start         End      Blocks   Id  System
/dev/sdb1            2048     8390655     4194304    c  W95 FAT32 (LBA)
/dev/sdb2   *     8390656    62333951    26971648   83  Linux
[stuart@sturling ~]$ sudo fdisk -l /dev/sdc

Disk /dev/sdc: 100.0 GB, 100030242816 bytes, 195371568 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk label type: dos
Disk identifier: 0x8bef8bef

   Device Boot      Start         End      Blocks   Id  System
/dev/sdc1            2048   178593791    89295872   83  Linux
/dev/sdc2       178593792   195371007     8388608   82  Linux swap / Solaris

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#4 2013-09-11 23:55:38

cfr
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From: Cymru
Registered: 2011-11-27
Posts: 6,104

Re: [SOLVED] grub "unknown filesystem" error for big partition layout

Did you modprobe dm-mod before arch-chrooting to install grub to disk? I notice the instructions in the wiki include this but you don't mention it.


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#5 2013-09-12 00:13:36

STUART
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From: Seattle, WA
Registered: 2010-08-19
Posts: 42
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Re: [SOLVED] grub "unknown filesystem" error for big partition layout

I modprobed dm-mod after chrooting.

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#6 2013-09-12 00:15:39

cfr
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From: Cymru
Registered: 2011-11-27
Posts: 6,104

Re: [SOLVED] grub "unknown filesystem" error for big partition layout

That will only work if the kernel on the live media you used matches the installed kernel. Did it? If you modprobe before chrooting, it doesn't need to match - that's why the wiki specifies the order it does.


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#7 2013-09-12 00:22:44

STUART
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From: Seattle, WA
Registered: 2010-08-19
Posts: 42
Website

Re: [SOLVED] grub "unknown filesystem" error for big partition layout

Where does the wiki specify that order? https://wiki.archlinux.org/index.php/GRUB only specifies to do the modprobe first, then the grub-install. It doesn't actually mention chrooting at all.

Also, if there were a kernel issue, wouldn't I be seeing some kind of error?

Also, if this were the issue, wouldn't doing the grub-install from inside the booted environment (which I have done) have fixed it?

Last edited by STUART (2013-09-12 00:23:50)

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#8 2013-09-12 00:42:52

cfr
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From: Cymru
Registered: 2011-11-27
Posts: 6,104

Re: [SOLVED] grub "unknown filesystem" error for big partition layout

STUART wrote:

Where does the wiki specify that order? https://wiki.archlinux.org/index.php/GRUB only specifies to do the modprobe first, then the grub-install. It doesn't actually mention chrooting at all.

I thought it would say it in the installation guide (where the chroot is relevant) but it only seems to say this in the case of EFI booting (where modprobe efivars must be done prior to arch-chroot).

Also, if there were a kernel issue, wouldn't I be seeing some kind of error?

modprobe won't give an error - it will just silently fail. Not sure about grub-install.

Also, if this were the issue, wouldn't doing the grub-install from inside the booted environment (which I have done) have fixed it?

Yes, it should.


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#9 2013-09-12 01:54:09

STUART
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From: Seattle, WA
Registered: 2010-08-19
Posts: 42
Website

Re: [SOLVED] grub "unknown filesystem" error for big partition layout

Reading around, apparently the base GRUB searcher has issues finding ext* partitions after a large NTFS partition. Re-installing with this command set up the system so it could boot itself:

sudo grub-install --recheck --disk-module=native /dev/sda

However, this still presented some issues:

  1. Several failed attempts at finding the partition with all the incorrect modules had to come before the correct module could find it.

  2. When the menu was finally presented, it seems my keyboard didn't work.

  3. The menu wasn't at my native resolution (of course, I'm not sure it ever was.)

I'm working on alternate formulations of the install that will make it work now.

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#10 2013-09-12 02:06:11

cfr
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From: Cymru
Registered: 2011-11-27
Posts: 6,104

Re: [SOLVED] grub "unknown filesystem" error for big partition layout

For stuff like resolution, see /etc/default/grub (and the wiki which explains the options there).


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