btrfs problem 12.04

Johnny Rosenberg gurus.knugum at
Wed Oct 28 10:38:12 UTC 2015

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
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…


Johnny Rosenberg
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