[systemd-devel] Topics for the Linux Storage, Filesystem & MM Summit

Lennart Poettering lennart at poettering.net
Thu Feb 27 16:16:00 PST 2014

On Thu, 27.02.14 17:06, Chris Murphy (lists at colorremedies.com) wrote:

> On Feb 27, 2014, at 4:09 PM, Lennart Poettering <lennart at poettering.net> wrote:
> > - uuids for btrfs subvols
> btrfs subvol show <pathtosubvolume>
> It will show the subvol uuid, and if it's a snapshot it will also show
> the parent uuid. If you mean partitiontypeGUID so we have some idea
> what the purpose of these subvolumes is, like the unique
> partitiontypeGUID for home? Could be useful. Certainly there could be
> some additional metadata for tracking the relationship between many
> subvolumes as well as purpose.

Oh, sorry, yeah, i meant subvolume *type* UUIDs, indeed. i.e. like
the partition type UUIDs that GPT exposes for every partition. 

And yupp, this is about discovering automatically where to mount what
when just looking at a btrfs volume. 

> Possibly a snapshot family, that describes multiple subvolumes; and
> then use that information for a systemd mount job, it would make fstab
> mostly obsolete.

Instead of supporting too much flexibility I'd try to focus on
collecting the subvolumes by a simple rule, for example: just take the
first subvolumes with the right type uuids, or just take the oldest or
the newest ones, or so...

Anyway, sorry for the confusion!


Lennart Poettering, Red Hat

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