Mailinglist Archive: opensuse-factory (710 mails)

[Peter Linnell <mrdocs@xxxxxxxxxxxx>]

On 06/20/2011 01:38 PM, Susanne Oberhauser wrote:
> Jos Poortvliet <jos@xxxxxxxxxxxx> writes:
>
> > systemd does not support a separate /usr partition. This was a
> > decision of the devs - according to them there are lots of weird
> > corner cases with /usr on a separate partition and you shouldn't want
> > it.
> >
> > See: http://freedesktop.org/wiki/Software/systemd/separate-usr-is-broken
>
> If I'm reading that right, it *does* support a separate /usr, it's just
> some other players in the boot process don't any more.
>
>
> Wrt 'nobody needs a separate /usr', This guy is just uninformed, that's
> not bad and probably not his fault.  Possibly like most of us he started
> using Linux on his desktop and he's never seen more complex setups?
>
> Let me pick a few examples (from non-netbook worlds), examples that I've
> chosen because A) such uses are feeding almost every large Linux
> distribution and because B) these uses are key in what sets SUSE apart.
>
> First, having a separate, read-only mountable /usr partition allows
> diskless high performance computing clusters and data centers to share a
> networked /usr.
>
> If you have >2000 blades in your data centre, then you don't want to
> have someone replace a failed hard disk in one of them every single day.
> Which for 2000 machines is what you get: just one hard disk failure a
> day, if you're lucky.
>
> So you want the blades diskless.  And then on your storage system (where
> 1GB is a tad more expensive than at home) you have no interest to
> replicate the very identical /usr 2000 times for each of them.  You want
> /usr shared.
>
>
> Another use is massive parallell virtualisations, which share /usr as
> ramdisk in the very same physical RAM on one machine.  2000 Linux
> machines on 32CPUs, /usr on a ram disk that per guest just needs 500k.
> IBM did that on mainframe linux years ago, with several thousand snappy
> guests on a single machine.  That's how some some web hosters provide
> "your own dedicated Linux web server": One mainframe with several
> thousand virtualized Linux guests is *much* cheaper than a compute
> centre with several thousand physical 'dedicated machines'.
>
>
> Now I hear someone shout "corner cases!", and "server problem, not my
> problem!".
>
> Well.
>
> SUSE is the distribution with the most consistent "same environment from
> the appliance via desktop to the mainframe" story, since 1999.  We could
> do that because of the build server, which built the same Linux on
> sparc, aplpha, ppc, mips (!), x86. x86_64 and itanic.
>
> This philosophy of the very same Linux on any size hardware allows the
> young talented Linux netbook users of today to become professional Linux
> engineers later.  It also allows companies to just scale up the hardware
> and find the same environment and the same tools.  It allows to develop
> things on a netbook or laptop and then benefit from them on the 16-node
> server.
>
> It's a Good Thing.
>
>
> And: Everybody, high performance clusters, web farm hosters, desktop /
> netbook users wants a fast boot, the real objective of this discussion.
>
>
> And last not least I'm pretty sure that the problems systemd reveals (as
> per your link above) can be fixed.
>
>
>
> For /usr to be network mountable (diskless HPC cluster), you need to set
> up network before you mount /usr.  Whther / is an initrd for that
> purpose doesn't matter.
>
>
> I like the idea of cleaning up the udev rules and stuff that break a
> separate, read-only mountable /usr.
>
> To me it always was cool to have the same professional and versatile
> Linux on my laptop that I also used on the mainframe.
>
> So can we please focus an solving the problems that break a separate r/o
> /usr, instead of bashing on distinguished, experienced engineers that
> help us keep openSUSE the premier choice for *all* Linux uses, not just
> tabloid PCs?
>
>
> S.

I've not wanted to add to this lengthy thread, but the above is exactly
the world where openSUSE and SLES both are very competitive and it works
much as Suzanne has described.

http://www.top500.org/stats/list/35/os

Peter




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