Arch Linux

Hy Ginsberg

Member

From: Massachusetts

Registered: 2008-08-22

Posts: 74

Website

Can't mount root device after ext4 conversion

Ugh.  I just converted my root filesystem from ext3 to ext4 (by remounting it readonly in single user mode, running fsck.ext3 on it to make sure it was clean, then running tune2fs to turn on a bunch of ext4 features, and finally running fsck.ext4 on it).  All seemingly went well.  I rebooted.  I got the dreaded:

mount: mounting /dev/sda8 on /new_root failed: No such device
ERROR: Failed to mount the real root device.
Bailing out, you are own your own.  Good luck.

I've tried various flavors of the mount command by hand, including

mount -t ext4 /dev/sda8 /new_root
mount /dev/sda8 /new_root
mount /dev/sda8 /

to no avail (with the "-t ext4" option I get "No such device", without it I get "No such file or directory").

So, do I have to start over from scratch and reinstall the whole system over again, or might there still be hope for resurrection?  Or is there something in between that might save me from a full install of everything?

Thanks for any help.

- Hy

Update: I just tried

mount -t ext3 /dev/sda8 /new_root

and got:

EXT3-fs (sda8): error: couldn't mount because of unsupported optional features (40)
mount: mounting /dev/sda8 on /new_root failed: Invalid argument

Update: And maybe there's some possible help here: I have a separate boot partition that I created yesterday that I haven't been able to boot from (couldn't get GRUB to recognize it -- see https://bbs.archlinux.org/viewtopic.php?id=120867), but it's still ext3 and I am able to mount it.  So it has kernel images.

Last edited by Hy Ginsberg (2011-06-15 14:38:33)

andrewthomas

Member

Registered: 2010-05-08

Posts: 52

Re: Can't mount root device after ext4 conversion

Are you using an initrd?  You may have to regenerate it in a chroot to get it to include support for ext4.

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ewaller

Administrator

From: Pasadena, CA

Registered: 2009-07-13

Posts: 20,353

Re: Can't mount root device after ext4 conversion

Are you using UUIDs to identify your partitions?  Any chance a UUID changes when you change file systems (I don't know, but you could check that)

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kishd

Member

Registered: 2006-06-14

Posts: 401

Re: Can't mount root device after ext4 conversion

Don't know if this is still needed but I had to add the following kernel parameter "rootfstype=ext4" a long time ago when I converted to ext4.

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Hy Ginsberg

Member

From: Massachusetts

Registered: 2008-08-22

Posts: 74

Website

Re: Can't mount root device after ext4 conversion

Thanks for all the responses.  I was not using an initrd, and I was not using UUIDs to identify partitions.  The kernel parameter might have helped, but it's too late to try -- in the end I had to reinstall from scratch.

Last edited by Hy Ginsberg (2011-06-29 13:02:43)