[Mageia-dev] Please test: initscripts+systemd in updates_testing

Colin Guthrie mageia at colin.guthr.ie
Wed Nov 2 13:02:20 CET 2011

'Twas brillig, and Johnny A. Solbu at 02/11/11 02:49 did gyre and gimble:
>>> Since you have read the reference, you didn't notice that the
>>> option of separate partitions is _not_ precluded ?

> Some of the answers I got here suggested otherwize. if /usr needs to
> be mounted in order for the system to boot normally. Then have
> systemd mount it.
> I do see that there might be some problems involved in solving it.

That's catch-22 problem. systemd uses various bits to detect this disk
subsystems, including encryption, lvm, raid, etc. etc. layers. That
means for systemd to deal gracefully with /usr being on a separate mount
mount, it must ensure that all of those tools (and of course systemd
itself) and are located outside of /usr and this is the whole point that
is being made. For various setups etc. you need to move a whole bunch of
stuff to / to cope with this. Rather than doing that, the suggest is
instead to move that stuff to the initramfs.

This has several advantages. It means that the vast bulk of the
applications installed can live inside a single tree - /usr. This means
that the /usr tree can be MUCH more useful than currently - it can be
exported over NFS/SAN/whatever and shared on multiple machines, mounted
read only. Much less hassle to administer one install than 5000. It also
aids snapshotting (at the filesystem level). which also makes backups
more robust etc. etc. The benefits just flow from here.

So the argument is that it will not be systemd's job to do it because
systemd very much *wants* to live inside /usr.

So the job of mounting /usr is in the initramfs. After that, systemd
does everything. It's a nice and clean separation.

But this list really isn't the place for this discussion. We are not
upstream systemd. If you want to discuss it further, please take it to
the systemd list, and let's end this thread which has gone massively off



Colin Guthrie

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