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Old 07-02-2012, 07:00 PM
Les Mikesell
 
Default Question about storage for virtualisation

On Mon, Jul 2, 2012 at 1:42 PM, Stephen Harris <lists@spuddy.org> wrote:
>
> I'm just saying that I don't see it causing any true pain.
>

It may not - but it is always annoying to me when committees get
together and move arbitrary things around just because they can. And
even more so when they want to turn Linux, whose success is clearly
based on the unix design into something that is not like unix.

--
Les Mikesell
lesmikesell@gmail.com
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Old 07-02-2012, 07:08 PM
Gordon Messmer
 
Default Question about storage for virtualisation

On 07/02/2012 11:18 AM, Les Mikesell wrote:
> You aren't done booting until you complete the init scripts for
> runlevel 1.

You may not have noticed, but there is no longer any such thing. Red
Hat's init system never booted *through* runlevel 1, the way that some
other Unix systems did.

Even on older Red Hat systems, /usr is mounted before the runlevel 1
scripts run. It's mounted in rc.sysinit. By your logic, you aren't
done booting until you have both / and /usr mounted, so there's no value
in separating them.

> Having to have an extra copy of the kernel on yet another
> device to even get started seems wrong from a minimalist approach, and
> the need for sufficient ram for an initrd even more so. And you
> really should be able to mount /usr via nfs while retaining
> independent boot/diagnostic capability.

No part of the merge requires and additional copy of the kernel or
initrd, and I'm not sure where your confusion on the subject originates.

Prior to the merge, you could not reliably mount /usr from NFS, since it
might not match the libraries in /. Merging / in to /usr actually makes
an NFS root filesystem a supported configuration, which was not
previously the case.

Twice in this message, you've actually argued *for* merging the two
without realizing it.
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Old 07-02-2012, 07:25 PM
Les Mikesell
 
Default Question about storage for virtualisation

On Mon, Jul 2, 2012 at 2:08 PM, Gordon Messmer <yinyang@eburg.com> wrote:
>
>> You aren't done booting until you complete the init scripts for
>> runlevel 1.
>
> You may not have noticed, but there is no longer any such thing. Red
> Hat's init system never booted *through* runlevel 1, the way that some
> other Unix systems did.

Yes, I noticed - and didn't see the point in that either. Why copy
the runlevel 'look' of sysV if you aren't going to take advantage of
it?

> Even on older Red Hat systems, /usr is mounted before the runlevel 1
> scripts run. It's mounted in rc.sysinit. By your logic, you aren't
> done booting until you have both / and /usr mounted, so there's no value
> in separating them.

Right. It was broken before. Which is mostly why I don't have a lot
of faith in the next round of changes either.

> Prior to the merge, you could not reliably mount /usr from NFS, since it
> might not match the libraries in /. Merging / in to /usr actually makes
> an NFS root filesystem a supported configuration, which was not
> previously the case.
>
> Twice in this message, you've actually argued *for* merging the two
> without realizing it.

I was arguing against the broken ways that the layout has diverged
from the unix design concepts more than any specific thing. If this
is going to make everything work again, great. This time for sure...

--
Les Mikesell
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Old 07-02-2012, 07:35 PM
Gordon Messmer
 
Default Question about storage for virtualisation

On 07/02/2012 12:00 PM, Les Mikesell wrote:
> It may not - but it is always annoying to me when committees get
> together and move arbitrary things around just because they can.

The change wasn't made just because someone could. It was made to
improve software and script portability, to make and NFS-mounted /usr a
supported configuration, and to allow yum to take system snapshots so
that it can roll back upgrades in the future. All of those required the
merge.

http://www.freedesktop.org/wiki/Software/systemd/TheCaseForTheUsrMerge


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Old 07-03-2012, 11:57 AM
"William L. Maltby"
 
Default Question about storage for virtualisation

On Mon, 2012-07-02 at 15:48 +0200, Tilman Schmidt wrote:
> Am 01.07.2012 07:40, schrieb Les Mikesell:
> [distinction between /bin and /usr/bin]
> > The concept really comes from the original unix, which back in the
> > day, often had really tiny boot disks and might mount everything else
> > over the network or use different drive types to hold the larger /usr
> > space.
>
> The separation predates Unix networking. IIRC /usr/bin was
> already there on Unix Version 7 on the PDP-11, before Ethernet
> was even invented.
>

You are correct. I used to create and mail the tapes out with the
software releases to the government and colleges. Ran V6/V7 on Dec
PDP-11, early PC-compatible stuff (maybe System II used? Can't recall
for sure), 5B5/3B20 (AT&T designed hardware used when System III & V
came available, IIRC) ... when a big HD was 10MB (or even 5MB) and
memory was 64K and processors where 8086, 80186, 80286, ...

Everything was small, highly unreliable compared to today. HDs were
sliced up to try and ensure minimal damage when the inevitable crash
occurred. Backup process recommended was "Tower of Hanoi" strategy on
tape (which were also limited in size). A thing called "speed" was
non-existent compared to today. So another reason for slicing was to
reduce fsck times.

The internet was not yet invented, but uucp and related provided
"networking" capability.

I gave a one day class to some *very* smart folks at DARPA and you know
what happened next - "internet".

Bill

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Old 07-03-2012, 06:30 PM
Nate Duehr
 
Default Question about storage for virtualisation

Appreciate all the discussion, folks.

Got some boxes that have some separate / and /usr, since we're a /usr/local religion shop. (GRIN...) Someone long long ago, in a galaxy far, far away picked /usr as the split point, instead of /usr/local itself. So...

Layers 8 and 9 of the OSI model, bite again... Religion and Politics.

Guess we'll be moving to /opt or /usr/local being the separate mountpoint. I'm sure this will be a happy internal discussion... hahaha...

Nate
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