Kernel panic - unable to mount root fs

Bugs
1

Can no longer boot Rockstor due to kernel panic
4.10.6-1.el7.elrepo.x86_64

will still boot using kernel: 4.8.7-1.el7.elrepo.x86_64

Any advice would be appreciated.

Error screen states:
Kernel panic - not syncing : VFS : Unable to mount root fs on unknown-block(0,0)

2

A bit more data would help …
your setup
if you can connect a screen and show what error is being spit out …

“can’t mount fs” is a very broad problem …

3

My apologies tomasz.

Am operating a HP N40L Server

Screenshot of error attached.

IMG_4698.JPG2016Ă—1512 1.01 MB

4

I would advise to search the internets for “prepare_namespace” and “mount_block_root” but those 2 spots seems to be pretty bad …

  1. I hope that this is not a main FS that it’s craping out on.
  2. pointless to say: “backups ?”

I’m not sure I’ve made this clear before but alto N40L is a cheap and cheerful system to run (power consumption wise) that is a complete crap generating errors and sending people data to data heaven :slight_smile: You may not know it but fact you’re not using ECC ram means you are asking for it … I’m not jumping down on you … it’s simply impossible to expect anybody trying to be serious about data storage to know this somehow contradicting fact - but ECC ram is a must in storage systems … 95% of problem are eliminated by having ECC …

As an explanation here - all modern “advanced” filesystems keep a large hierarchy / structures / trees in RAM to accelerate operations and keep data syncing optimal (zfs, btrfs, xfs) … down side is that is you get an error in ram … it may confuse algorithms operating on this data and next time it will sync to hard storage you might as well end up with large array or random 0 and 1 :frowning:

1 Like
5

Thanks for the advice Tomasz - am learning a lot.

The odd thing here is that in using the previous kernel (4.8.7-1.el7.elrepo.x86_64)

  • the system boots and operates perfectly…
6

Closing the loop on this one.

I got this resolved via:

sudo yum remove kernel-4.10.6-1.el7.elrepo.x86_64
yum install yum-utils
yum-complete-transaction --cleanup-only

This then allowed a re-install of the kernel via:
yum update

back up and running.

3 Likes
7

Cool. So after cleanly removal and reinstall of the 4.10 kernel, you are able to boot into it again?

8

Which sound plausible - “prepare namespace” might mean that headers / modules / kernel got out of sync …

9

I also had this issue - thank you so much for posting it. Given that there now appears to be 3 of us - is this a bug?