bugGNU GRUB - Bugs: bug #35667, error: unknown filesystem. grub...


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bug #35667: error: unknown filesystem. grub rescue> after Ubuntu 11.10 install

Submitter:  Tranas Spietis <tranas>
Submitted:  Wed 29 Feb 2012 02:59:20 PM UTC
Category:  Booting Severity:  Major
Priority:  5 - Normal Item Group:  Software Error
Status:  Invalid Privacy:  Public
Assigned to:  None Originator Name:  Cannonical
Open/Closed:  Closed Release:  other
Release:  Reproducibility:  Every Time
Planned Release:  None

( Jump to the original submission )

Sun 03 Jun 2012 12:51:38 PM UTC, comment #11: 

The reporter failed to provide the requested info (output of "ls -l" and whether grub-fstest and grub-probe work), instead supplying loads of irrelevant unrequested info. Since there is a plausible explanation (BIOS limit) and workaround (--disk-module), closing the bug report.

Vladimir Serbinenko <phcoder>
Project Administrator
Sun 04 Mar 2012 01:19:57 AM UTC, comment #10: 

The storage controller isn't a problem either. Possible source of problem is BIOS, not controller. Which filesystem is it? Do grub-fstest and grub-probe work?

Vladimir Serbinenko <phcoder>
Project Administrator
Thu 01 Mar 2012 03:31:43 AM UTC, comment #9: 

Belarc reports the storage controller on this machine to be an
Intel 82801CAM Utra ATA Storage controller-248A
SIW shows the same controller

From the Intel® 82801CA I/O Controller Hub 3-S: Datasheet -
• Integrated IDE controller supports Ultra ATA100/66/33

From the ATA-ATAPI-6 documentation-

• standard
ATA/ATAPI-6, ATA-6, Ultra ATA/100
• transfer modes
UDMA 5, aka UDMA/100
• maximum disk size
128 PiB (144 PB)
• features
48-bit LBA, Device Configuration Overlay (DCO), Automatic Acoustic Management (AAM)

Tranas Spietis <tranas>
Wed 29 Feb 2012 07:04:43 PM UTC, comment #8: 

None of software you mentioned uses BIOS for accessing disks

Vladimir Serbinenko <phcoder>
Project Administrator
Wed 29 Feb 2012 06:59:51 PM UTC, comment #7: 

Seems the issue is the inability of Grub2 to access the files.

Read the output of root@PartedMagic:~# fdisk -l

All the following have no issue accessing the full 250 GB drive -

Linux Terminal
Acronis True Image
Acronis Disk Director

NONE throw an error: unknown filesystem. Grub2 does.

Tranas Spietis <tranas>
Wed 29 Feb 2012 06:23:04 PM UTC, comment #6: 

Some BIOS are limited to some particular disk size, usually 128GiB. You can check this by booting into a working GRUB (e.g. on external storage and issuing ls -l and compare reported disk size with real one)

Vladimir Serbinenko <phcoder>
Project Administrator
Wed 29 Feb 2012 06:20:11 PM UTC, comment #5: 

I would also point out, that this particular machine has used Acronis TrueImage v8.0 build 937 since it was released - and Acronis has no issues with the BIOS. As I understand it, Acronis is essentially Linux code - rewrites the MBR when creating and restoring partition images from within Windows. Gparted from withing PartedMagic also has no issues resizing, formatting, setting flags or designating the boot partition - be it linux, swap or ntfs. 

Possibly something that Cannonical does with Grub2??

Tranas Spietis <tranas>
Wed 29 Feb 2012 06:03:38 PM UTC, comment #4: 

Possibly you can direct me on how to determine if this particular BIOS is "buggy"?

There is only 1 later BIOS version -
2.10 - but the update does not appear to apply to boot
- (New) Support IBM 11bg Wireless LAN Mini PCI Adapter.

Property Value
BIOS Version 1IET70WW (2.09 )
Firmware Version 77.0
BIOS Date 08/08/2005
BIOS Size 1024 KB
BIOS Starting Segment DC00h
DMI Version 2.31
Characteristics - supports PCI
- supports PC Card (PCMCIA)
- supports Plug-and-Play
- supports APM
- upgradeable (Flash) BIOS
- allows BIOS shadowing
- ESCD support is available
- supports booting from CD-ROM
- supports selectable boot
- supports booting from PC Card (PCMCIA)
- supports Enhanced Disk Drive specification
- supports INT 13 3.5-inch/720K floppy services
- supports INT 05 print-screen
- supports INT 09 and 8042 keyboard services
- supports INT 14 serial services
- supports INT 17 printer services
- supports INT 10 CGA/Mono video services
- supports ACPI
- supports AGP
- supports booting from LS-120
- BIOS Boot Specification supported

Tranas Spietis <tranas>
Wed 29 Feb 2012 04:41:58 PM UTC, comment #3: 

Yes, it is default but it's unsuitable for some buggy BIOSes.

Vladimir Serbinenko <phcoder>
Project Administrator
Wed 29 Feb 2012 03:33:20 PM UTC, comment #2: 

No, I have not.

Thought that the MBR was easiest/most convential setup.

Seems to be the default in most cases.

Tranas Spietis <tranas>
Wed 29 Feb 2012 03:11:55 PM UTC, comment #1: 

Have you tried making a separate /boot at the beginning of the disk?

Vladimir Serbinenko <phcoder>
Project Administrator
Wed 29 Feb 2012 02:59:20 PM UTC, original submission:  

error after a fresh dual boot install of Ubuntu 11.10 on a WinXP Thinkpad laptop - fixboot+fixmbr will repair MBR and allow windows to boot.

Single disk, no raid.

Used boot-repair-disk
Executed the 1 click recommended repair
Executed the "Purge and reinstall" option
neither resolves the issue

Filed bug report

repartitioned disk with 4 primary partitions - repeat install of Ubuntu 11.10 - same error message

Used RescaTux
Executed Restore Grub
Executed Update Grub
neither resolves the issue


PartedMagic has no problem reading the Linux partition [sda3]
fully functional from RAM

Welcome - Parted Magic (Linux 3.1.6-pmagic)

root@PartedMagic:~# fdisk -l

Disk /dev/sda: 250.1 GB, 250059350016 bytes
255 heads, 63 sectors/track, 30401 cylinders, total 488397168 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 identifier: 0x9d6525c0

   Device Boot      Start         End      Blocks   Id  System
/dev/sda1   *          63    31449599    15724768+   7  HPFS/NTFS/exFAT
/dev/sda2        31449600   465317999   216934200    7  HPFS/NTFS/exFAT
/dev/sda3       465318000   486289439    10485720   83  Linux
/dev/sda4       486291456   488396799     1052672   82  Linux swap

From the grub rescue prompt:

error: unknown filesystem.
grub rescue> set
grub rescue> insmod normal
error: unknown filesystem.
grub rescue> ls /boot
error: unknown filesystem.
grub rescue> insmod linux
error: unknown filesystem.
grub rescue> set prefix=(hd0,3)/boot/grub
grub rescue> set
grub rescue> set root=(hd0,3)
grub rescue> set
grub rescue> insmod normal
error: unknown filesystem.
grub rescue> ls /boot
error: unknown filesystem.
grub rescue> insmod linux
error: unknown filesystem.
grub rescue> insmod (hd0,3)/usr/lib/grub/i386-pc/normal.mod
error: unknown filesystem.

Using PartedMagic -

/media/sda3/boot/grub contains
normal.mod [104.2KB]
/media/sda3/boot/ contains [among others]

Assistance in resolving this issue would be appreciated.

Tranas Spietis <tranas>


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    Follow 3 latest changes.

    Date Changed by Updated Field Previous Value => Replaced by
    2012-06-03 phcoder StatusNone Invalid
        Open/ClosedOpen Closed
    2012-02-29 tranas Carbon-Copy- Added tranas

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