Am Samstag, 27. April 2019, 21:35:18 CEST schrieb Dave Howorth:
On Sat, 27 Apr 2019 20:06:38 +0200 Christian Boltz
> Am Samstag, 27. April 2019, 09:40:03 CEST schrieb Axel Braun:
> > I updated TW this morning, and now it looks like this (shortened):
> > # | Typ | before# | Date | Space |
> > Descript.
> > -----+--------+---------+--------------------+------------+-------
> > ---- -- 0 | single | | | |
> > current 549* | single | | Sa 30 Mär 21:17:16 | 21,11 MiB
That gives some insghts:
- Still 549 is mounted!
Yes, of course.
When using the "usual"/"traditional" setup, you can think of the
additional snapshots as "backups" that are done before and after
installing packages etc. As every good backup, they are hopefully
superfluous and get thrown away sooner or later ;-)
The snapshot that gets used will only change if you use "snapper
rollback". (And I guess you used "snapper rollback" in the past,
because otherwise you'd have #1 instead of #549 mounted at /.)
This confuses me. Surely if any snapshot is in use it will be the
latest one after the last zypper action? Otherwise, it doesn't
correspond to my idea of what yast or zypper do. How can the running
system precede the latest changes?
The "current" snapshots is always the newest, even if the other
snapshots have a higher number.
What would happen if I rolled back
to snapshot 549? Shouldn't that be an older, different state?
Nothing, because you would rollback from 549 to 549.
I'll try to explain it with traditional filesystems.
Let's say you have an ext4 on /dev/sda1 as your / partition.
Before running zypper, you do a backup/snapshot:
dd if=/dev/sda1 of=/dev/sda2
(Of course dd isn't the usual way to do backups, but it's close to what
taking a snapshot does, at least as long as you ignore the required disk
Now you run zypper dup and reboot. Your system still boots from
/dev/sda1, and that partition has all the new packages you just
Does that make it clear?
Now translate that back to btrfs:
/dev/sda1 -> snapshot 549 (current, including the updated packages)
/dev/sda2 -> one of the 573..583 snapshots (with the old packages)
version of this is on
(which I abused ;-) for a btrfs talk in my LUG recently - thanks
Maybe you should, it helps to understand btrfs and snapshots ;-)
also the option to use transactional updates
But IIRC, using Tx updates is not a good idea?
It depends on your usecase.
IMHO the biggest problem with transactional updates is that you need to
reboot after installing a package, which can be very annoying if you
need an additional program quickly. Actually that's the only reason why
I decided against using transactional updates on my laptop.
["superfluous" snapshots when YaST doesn't do any changes]
I agree that the pre-snapshot has to be taken
'pre' otherwise there's
no point. But if the yast session is abandoned surely the correct
action to take is to remove the pre snapshot, not create an
essentially unchanged after snapshot as well?
That would also be an option, but probably  isn't much easier than
not creating the pre snapshot at all - my guess is that every YaST
module would have to be touched to implement this.
That said - if
you want to get rid of these superfluous snapshots,
feel free to open a bugreport - I'd say it's a valid bug ;-)
Does that mean you agree with me?
I'm "just" saying that it's not the most critical bug we have, and that
fixing it will need quite some time.
Nevertheless, feel free to open a bugreport ;-)
 I don't know the YaST code, therefore I can only guess
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