On Wed, Jan 19, 2022, at 6:38 AM, Neal Gompa wrote:
On Wed, Jan 19, 2022 at 6:05 AM Casey Jao via devel
<devel(a)lists.fedoraproject.org> wrote:
>
> Doesn't rpm-ostree already provide transactional, image-based updates without the
use of filesystem snapshots? In addition, roofs snapshots are only really useful if they
are coordinated with bootloader management, which is already built into rpm-ostree but not
yet written for a hypothetical btrfs-based atomic os updater.
I think the bigger value would be around being able to use filesystem
snapshots with /var.
Right. In the ostree model the idea is all user data (except config files in /etc) are in
/var. So if you want to back up all machine-local state (including your home directories,
container storage, libvirt VMs, etc.), you just need one filesystem to save.
It could make sense to save a snapshot of /var before performing major OS upgrades. But
they're not strictly related. (As an aside: personally, I think snapshots have mostly
just obscure use cases versus backup systems)
I would agree with Casey though in that the opposite case of trying to snapshot /usr (and
then boot it) outside of ostree's control is likely to confuse ostree at best at least
today.