General Fedora Btrfs ticket is tracked as fedora-btrfs/project#50.

This seems like an aspect of the discussion about homed and user data encryption. Do we need a separate ticket for it?

This is orthogonal to homed, since we can do this without homed today.

This is orthogonal to homed, since we can do this without homed today.

But it seems like it would be better to wait and see how homed plays out? Or, if you think we should do it ASAP, then let's put that to the WG to decide.

The main value for doing it now is making it easier to something like Time Machine for user data, since snapshotting or doing btrfs send of a subvolume is possible.

Maybe some folks could try this layout locally, and see what happens? What are the cons? fedora-btrfs/project#50 has a couple of concerns listed: backup programs and the installer.

@lennart told us a few weeks ago that there's an early idea (perhaps it's "could happen" more than "will happen") of having systemd-homed learn about Btrfs snapshotting for this purpose; it already has subvolume support: A "btrfs" subvolume for each user, also located in /home/.homedir. This provides no encryption, but good quota support.*

Is the idea to have a way to convert from one subvolume regime to another? Just because it's subvolume based doesn't mean it'll "just work" with the systemd-homed way of doing things. Do we really want to do that work? We'd have to plan for that. Or alternative just wait and have one change instead of, in-effect, two changes? And while it's fairly simple to convert from one subvol regime to another (cp -r) it's harder to convert from one snapshot regime to another. We don't have a spec for any of that, it's all very tool specific with a ton of assumptions made by each tool.

And so on...

Seems like this would benefit from a wider discussion - setting the meeting label.

From last week's meeting:

ACTION: Neal to file the bugs he found and get them fixed. Then we can revisit this. Chris to help out too (cmurf, 03:46:54)

Refreshing my memory on this:

• shadow-utils set the home subvolume to be owned by root instead of the new user, need to verify if this is still a problem. If it is, file a bug.

@ngompa looks like you have the action item here.

@ngompa could you provide a status update please?

We discussed this on Tuesday's working group call. It seems that the main advantage of user directories as subvolumes is that, when encrypted, they can be backed up without the need for decryption.

This change is still wanted. The next step is to figure out how to use shadow-utils to do it - if someone wants to help with that, then that would be great.

This might break the trash feature?

We discussed this on Tuesday's working group call. It seems that the main advantage of user directories as subvolumes is that, when encrypted, they can be backed up without the need for decryption.

This change is still wanted. The next step is to figure out how to use shadow-utils to do it - if someone wants to help with that, then that would be great.

@ngompa can you provide a status update on this please? The action item is assigned to you.

It fell off my radar, but it's on my list to investigate and test, especially as a precursor to other interesting work around encryption and easy replication.

We discussed this on Tuesday's working group call. It seems that the main advantage of user directories as subvolumes is that, when encrypted, they can be backed up without the need for decryption.

This doesn't seem like a real advantage to me. When backing up, you surely want to exclude locations like cache directories and trash, and possibly git repos, and possibly container images and virtual machines, etc. Certainly you don't want to back up caches. In practice, my home directory often has 500 GB or more of data that should not be backed up and only about 30 GB of data that does belong in backups.

Looking over the concerns raised in https://pagure.io/fedora-btrfs/project/issue/50, it actually looks like this change would break several popular backup programs. Maybe we should just not do it?