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I have the following problem:

I can't figure out, how to create a snapshot of a btrfs volume residing on a crypted disk.

This is the setup:

/dev/sdb is a 1TB USB 3 disk. it has a partition /dev/sdb1, which fills the whole space.

This partition was overwritten with random data before creating a luks device with

cryptsetup luksFormat -v -y -c aes-xts-plain64 -s 512 /dev/sdb1

it was then opened with

cryptsetup luksOpen /dev/sdb1 platte

and a filesystem was created via

mkfs.btrfs -L MuPla /dev/mapper/platte

/dev/mapper/platte mounts nicely, i was able to fill it with files last night.

At this point i wanted to make a snapshot to be able to track file changes. Here comes the problem:

btrfs device scan

does not list the filesystem.

Neither 

btrfs subvolume snapshot /dev/mapper/platte snap-2014-11-10

nor 

btrfs subvolume snapshot /run/media/mymountpoint snap-2014-11-10

work Could you help me with that?

Thanks in advance.

Stephan Richter
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  • Error output & logs would have been too helpful, wouldn't they? A "It doesn't work" without any information would have been better :-) – Wolfgang Nov 09 '16 at 19:24
  • Hm, this question has been asked 2 years ago. I don't have logs from back then and even I can't remember how I finally circumvented the problem. But I think, if I have had any output or relevant logs, I would have posted them. In other words: I don't think an actual error occurred; I believe there was a bug which just made btrfs subvolume return an empty set. – Stephan Richter Nov 10 '16 at 15:49

0 Answers0