Boot problem - Unable to mount root fs on unknown-block(0,0)

Questions about SolydX and SolydK installation.
vacnt
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Boot problem - Unable to mount root fs on unknown-block(0,0)

Postby vacnt » 25 Oct 2015 18:50

I have been getting this Kernel panic problem lately. This problem doesn't happen if
  • I go to grub edit (by pressing e) and then press F10 without making any change.
  • I go to grub edit and exit (ESC), and then press enter to boot.
This problem still happens if
  • I stop the grub timer and wait a bit (from a few seconds to a few minutes) without going into edit, then press enter to boot.
  • I go to grub shell by pressing c and "ls /" shows correct HDD content, and exit (ESC) then press enter to boot.
This only started happening a few months ago maybe after an update. I clean installed a couple of SolydX versions, sometimes it worked fine for a couple of weeks before failing, and other times, it failed to boot right after install.

I have a few computers with the official 64-bit SolydX installed, this problem only affects one of them.

Could it be a faulty SATA controller? How do I debug this?

Code: Select all

[0.343056] ---[ end Kernel panic - not syncing: VFS: Unable to mount root fs on unknown-block(0,0)

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Zill
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Re: Boot problem - Unable to mount root fs on unknown-block(

Postby Zill » 25 Oct 2015 20:33

vacnt: Check if you have sufficient disk space... Open a terminal and post the full output of the following command:

Code: Select all

df -h

vacnt
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Re: Boot problem - Unable to mount root fs on unknown-block(

Postby vacnt » 25 Oct 2015 21:51

Yes, I do have sufficient disk space, only 4% is used. I tried clean installation (disk reformatted) several times, I also used disk manufacturer's utility to zero fill the whole disk multiple times, and ran badblocks destructive write test repeatedly overnight, and the disk passed SMART long test with no bad sectors remapped.

Some articles suggest the 0 in block(0,0) error indicates the kernel cannot detect the storage controller, but I'm still at a loss as to why going into grub edit would make it work.

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Zill
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Re: Boot problem - Unable to mount root fs on unknown-block(

Postby Zill » 25 Oct 2015 22:57

vacnt wrote:Yes, I do have sufficient disk space, only 4% is used.
This is ambiguous. We don't know how your disk is partitioned and so that is why I asked you to post the full output of the "df -h" command.

It may be that only 4% of the total disk space is used but if the root or /boot partition is using almost 100% then this could be the cause of the problem.

vacnt
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Re: Boot problem - Unable to mount root fs on unknown-block(

Postby vacnt » 26 Oct 2015 11:46

OK, I'll get the command output when I have the computer with me. 4% was the highest number in the used space column when I checked.

I'm quite sure that the disk space is fine, the disk is not partitioned, it's formatted with btrfs

Code: Select all

mkfs.btrfs /dev/sda
There're 2 subvolumes which mount to / and /home.

I have the same setup on other computers without any problem.

vacnt
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Joined: 23 Oct 2014 19:24

Re: Boot problem - Unable to mount root fs on unknown-block(

Postby vacnt » 26 Oct 2015 20:44

Here's the "df -h" output

Code: Select all

Filesystem      Size  Used Avail  Use% Mounted on
/dev/sda        150G  7.2G  141G    5% /
udev             10M     0   10M    0% /dev
tmpfs           198M  5.2M  193M    3% /run
tmpfs           495M   92K  495M    1% /dev/shm
tmpfs           5.0M  4.0K  5.0M    1% /run/lock
tmpfs           495M     0  495M    0% /sys/fs/cgroup
/dev/sda        150G  7.2G  141G    5% /home
tmpfs            99M  4.0K   99M    1% /run/user/112
tmpfs            99M  8.0K   99M    1% /run/user/1000

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Zill
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Re: Boot problem - Unable to mount root fs on unknown-block(

Postby Zill » 26 Oct 2015 21:20

vacnt: Thank you for posting the requested output and, as you say, it looks like the problem is not down to a lack of disk space.

Unfortunately, I have no other ideas about what could cause this and, as I have no experience of btrfs, I doubt if I can assist any further on this one.

Hopefully, other users will be along shortly with some other suggestions...

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Arjen Balfoort
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Re: Boot problem - Unable to mount root fs on unknown-block(

Postby Arjen Balfoort » 28 Oct 2015 19:34

Let's try these first:
  1. Boot a live DVD and open a terminal.
  2. Run these commands:

    Code: Select all

    sudo mount /dev/sda1 /mnt
    sudo mount --bind /dev /mnt/dev
    sudo mount --bind /dev/pts /mnt/dev/pts
    sudo mount --bind /proc /mnt/proc
    sudo mount --bind /sys /mnt/sys
    sudo chroot /mnt 
  3. In chroot, run these commands:

    Code: Select all

    update-initramfs -t -u -k all
    update-grub


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vacnt
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Re: Boot problem - Unable to mount root fs on unknown-block(

Postby vacnt » 29 Oct 2015 21:39

I tried
    1. Boot from 201506 Live DVD image
    2. Run the listed mount commands (/dev/sda), chroot, update-initramfs and update-grub
    1. Boot from HDD by pressing e then ESC then enter
    2. Run

      Code: Select all

      sudo update-initramfs -t -u -k all
      sudo update-grub
Results: tried both methods a few times, sometimes first few reboots worked fine before failing, sometimes it failed on first reboot. The symptom is very similar to the reboot after clean installation

Now "e - ESC - enter" doesn't work, I need "e - F10"

It seems that "update-grub" affects the boot process a bit, but it doesn't fix the problem. I may give 201501 iso a try, and also enable debug logging

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Arjen Balfoort
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Re: Boot problem - Unable to mount root fs on unknown-block(

Postby Arjen Balfoort » 29 Oct 2015 21:48

I'm afraid to suggest this but have you considered that the disk might be damaged?


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vacnt
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Re: Boot problem - Unable to mount root fs on unknown-block(

Postby vacnt » 30 Oct 2015 09:39

Yes, when I first saw the problem, the first thing that came to my mind was the disk had gone bad,

so I used disk manufacturer's utility to zero fill the whole disk multiple times, and ran badblocks destructive write test repeatedly overnight, and the disk passed SMART long test with no bad sectors remapped,

so I'm not so sure it's a disk problem, but it could be a storage controller problem as there're websites suggesting block(0,0) error indicates the kernel cannot detect the controller, but if it's a controller problem, I'd expect the computer to fail to load grub sometimes, and OS to be unstable, but I'm not seeing any of these.

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Arjen Balfoort
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Re: Boot problem - Unable to mount root fs on unknown-block(

Postby Arjen Balfoort » 30 Oct 2015 10:16

If you have a spare HD or can lend one that might be a good test.

I'm afraid I'm out of ideas right now :(


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vacnt
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Re: Boot problem - Unable to mount root fs on unknown-block(

Postby vacnt » 01 Nov 2015 18:03

I've tried the 201501 ISO, it works fine. Maybe my storage controller isn't properly supported by the new Initramfs in 201506 ISO?

I also tried adding the extra initramfs graphics modules used by the 201501 installation to the 201506 installation, then ran update-initramfs and update-grub, it didn't fix the problem.
The 201501 installation has the following two lines in /etc/initramfs-tools/modules

Code: Select all

uvesafb mode_option=1024x768-24 mtrr=3 scroll=ywrap
drm
I don't have a spare 2.5 inch HDD, but I can get a 3.5 inch HDD which I can use with a USB enclosure, not sure I'd try that given the working old ISO kind of suggests the hardware is fine (with certain software versions).

Working ISO:
http://downloads.solydxk.nl/solydx/solydx64_201501.iso

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Arjen Balfoort
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Re: Boot problem - Unable to mount root fs on unknown-block(

Postby Arjen Balfoort » 01 Nov 2015 19:19

Ah, that was the configuration needed for the old Plymouth version!
You could try to disable plymouth: remove "splash" from /etc/default/grub and run update-grub.


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vacnt
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Re: Boot problem - Unable to mount root fs on unknown-block(

Postby vacnt » 01 Nov 2015 22:17

I already have splash and quiet removed.
I've also tried rootdelay=180, it doesn't help.


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