Re: btrfs, ostree, systemd-nspawn creating subvolumes for containers

[Chris Murphy <lists colorremedies com>]

On Thu, Jul 16, 2015 at 6:33 AM, Colin Walters <walters verbum org> wrote:
> On Thu, Jul 16, 2015, at 12:11 AM, Chris Murphy wrote:
> > Hi,
> >
> > Does anyone know off hand what the interaction is between ostree and
> > systemd on btrfs when creating new ostrees and doing rollbacks? I
> > haven't tested this myself yet.
>
> OSTree never itself touches block storage.  So the answer is the same
> for anything in /var - it's untouched between upgrades and rollbacks
> by OSTree itself.
>
> You can't create subvolumes anywhere besides /etc and /var when
> using OSTree.

OK so /etc and /var are completely static and persistent, so booting
new or previous trees use the same /etc and /var.

> https://bugzilla.redhat.com/show_bug.cgi?id=1223467

I don't understand the reason why /var/lib/machines is a subvolume,
which then contains more subvolumes for each container. It's fine to
for systemd to make sure that directory exists but to create it as a
subvolume is specious, I don't see the point.

And whatever creates subvolumes should clean up subvolumes. I don't
thin, it's the responsibility of services to clean up things they
didn't create.

-- 
Chris Murphy