btrfs problem 12.04

[Petter Adsen]

On Wed, 28 Oct 2015 11:38:12 +0100
Johnny Rosenberg <gurus.knugum at gmail.com> wrote:

> My desktop computer, with Ubuntu 14.04, failed on me today, it just refuses
> to start. I think I tried at least 40 times. I suspect the graphics card,
> but never mind. So I went down to the… whatever it's called in Englist, a
> place outside my apartment for storing things that are not used regularly,
> in this case located in the cellar, and found my old laptop with Ubuntu
> 12.04. It's been a long time since I used it, so I didn't even remember if
> it works, but here I am now, typing this email with it.
> 
> Anyway, I have a USB HDD for backups and so on I wanted to bring the latest
> versions of all my documents back to this old laptop, mostly ODF files. The
> problem is that the USB disk is formatted as btrfs, which indeed is
> supported by Ubuntu 12.04 as well, but I get an error message that it can't
> be mounted. It asks me to do ”dmesg | tail” and here's the result:
> 
> ~$ dmesg | tail
> [ 2087.311210] sd 4:0:0:0: [sdb] No Caching mode page found
> [ 2087.311216] sd 4:0:0:0: [sdb] Assuming drive cache: write through
> [ 2087.327918] sdb: sdb1
> [ 2087.332476] sd 4:0:0:0: [sdb] No Caching mode page found
> [ 2087.332482] sd 4:0:0:0: [sdb] Assuming drive cache: write through
> [ 2087.332487] sd 4:0:0:0: [sdb] Attached SCSI disk
> [ 2087.929468] device label Backup 2000 devid 1 transid 1253 /dev/sdb1
> [ 2087.930331] btrfs: disk space caching is enabled
> [ 2087.930337] BTRFS: couldn't mount because of unsupported optional
> features (60).
> [ 2087.948115] btrfs: open_ctree failed
> ~$
> 
> So it seems like it ”couldn't mount because of unsupported optional
> features”.
> How can I install support for those ”optional features” on Ubuntu 12.04? I
> really need those files…
> I'm reasonably sure the disk isn't encrypted.
> I'm not very keen on upgrading to Ubuntu 14.04 at the moment since I now at
> least have something that kind of works…

You would need a newer kernel that has support for the btrfs features
that are missing from the 12.04 kernel.

https://wiki.ubuntu.com/Kernel/LTSEnablementStack

Petter

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