On 03/11/2016 01:01 PM, Chris Murphy wrote:
On Fri, Mar 11, 2016 at 10:38 AM, Matthew Miller
<mattdm(a)fedoraproject.org> wrote:
> On Fri, Mar 11, 2016 at 10:28:18AM -0700, Chris Murphy wrote:
>> A possible gotcha for Server is if the user installs Docker,
>> docker-storage-setup is installed and its systemd unit enabled. I
>> don't know if it immediately starts also, or only at next boot. But
>> upon running, all free extents in the VG are made into a dm thin pool.
>> I was imprecise when I wrote "On first boot, docker-storage-setup
>> turns those free extents into a thin pool LV." That implies it's an
>> LVM managed thin pool, which it isn't. It's only manageable by
>> dmsetup. This suggests some special handing for Server perhaps. Anyway
>> I found it really non-obvious when suddenly a bunch of free space was
>> gone and I couldn't manage it with LVM tools.
>
> That tool could probably be made smarter.
Sure. Right now it's non-interactive. And it makes sense for Cloud/Atomic.
It has a configuration file that allows limiting it to a VG with a
specific name. Cloud's installer could use that VG name at install
time. And Server installer could use a different VG name. Cockpit
Believe it or not, I think this is actually harder to change than the default
partition layout. The reason being that the default VG name is autodetected
based on hostname.
could offer a way to create a new VG with the proper name (or change
the docker-storage-setup configuration file), and migrate a specific
amount of free extents from the original VG to the new one, and then
docker-storage-setup would in effect take over that VG.
What does docker-storage-setup do if there are multiple VGs on the system? Does
it just pick one and use that, or does it take over them all?
Maybe the configuration should only take up 80% of free extents in a
VG instead of all of it? That could be a good idea anyway because when
the thin pool starts to get nearly used up, it'll start to complain in
logs, but is supposed to get to a point where it'll automatically grow
if there are free extents in the VG, rather than face planting (which
is spectacular BTW).