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Old 08-31-2012, 05:35 AM
Andrei POPESCU
 
Default Stuff from /bin, /sbin, /lib depending on /usr/lib libraries

On Vi, 31 aug 12, 06:39:19, Serge wrote:
>
> For example if filesystem is supposed to be network-mounted, and network is
> brought by the user, which logs into GNOME session and manually selects wifi
> connection in nm-applet, initramfs still does not help there, since you
> can't put entire gnome session into initramfs anyway.

Which filesystem would that be? If the network is supposed to be
"brought" by the user you already need /usr /home and probably /var
mounted just to let the user log in, so I doubt something like the above
works today.

Kind regards,
Andrei
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Old 08-31-2012, 06:53 AM
Thomas Goirand
 
Default Stuff from /bin, /sbin, /lib depending on /usr/lib libraries

On 08/30/2012 02:04 PM, Ben Hutchings wrote:
> And I suppose Marco must remove all /usr dependencies from everything
> that installs a udev hook too?
>
Why not? Is the only argument against that is that upstream
took such decision, and that the work to be done is too big?

Thomas


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Old 08-31-2012, 08:59 AM
Simon McVittie
 
Default Stuff from /bin, /sbin, /lib depending on /usr/lib libraries

On 31/08/12 04:39, Serge wrote:
> thus it reduces flexibility, breaking use cases, that were working before.

Please name them. "The ability to mount my /usr requires user
interaction via a UI in /usr" doesn't count, because it has never
worked, and is logically impossible.

> For example if filesystem is supposed to be network-mounted, and network is
> brought by the user, which logs into GNOME session and manually selects wifi
> connection in nm-applet, initramfs still does not help there, since you
> can't put entire gnome session into initramfs anyway.

If user interaction is required before you can mount enough filesystems
to interact with the user, then your configuration can't work; but
that's not a regression, because it can't work now either. Debian is
pretty flexible, but we can't do the impossible.

If a filesystem is not on the critical path to boot to the point where
you can get the prerequisites for mounting filesystems, you don't need
to mount it from the initramfs. (For instance, /srv isn't needed until
later.)

S


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Old 08-31-2012, 09:26 AM
Thomas Goirand
 
Default Stuff from /bin, /sbin, /lib depending on /usr/lib libraries

On 08/31/2012 11:39 AM, Serge wrote:
> Many (most?) major successes in IT history were about inventing a good
> standard communication interface to do things. IBM PC was successful
> because it could be assembled from standard easily accessible components,
> and was easy to upgrade by just replacing those components with newer
> ones. That worked so good because there were standard interfaces for
> devices (ISA, PCI, AGP, etc).
>

This is quite off topic, but I don't think that's the reason. The reason why
the PC platform won was because both Comodore and Atari failed because
of stupid decisions. They were largely superior platforms at the time (both
software and hardware) though, and a way cheaper.

> I suggest:
> 1. Define (implicitly or explicitly) where we would allow to mount subroot
> filesystems from (that decision mainly affects /usr and partially /var,
> /home and others) and what tools are needed to do that.
> 2. Make sure that all the tools from #1 are on / partition.
> 3. Make sure that everything required for `root` user to login (and do basic
> stuff, i.e. move files, read logs and edit scripts) is on / partition.
> 4. Don't move anything else around — unless it fixes something,
> it will just add more bugs and more problems for users

You don't need to suggest that, it has been rules inside Debian for years,
and I believe (almost) everyone understands it.

It's just that some would like to change these rules, and others are
resisting.

Thomas


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Old 08-31-2012, 09:39 AM
Thomas Goirand
 
Default Stuff from /bin, /sbin, /lib depending on /usr/lib libraries

On 08/31/2012 03:39 AM, Steve Langasek wrote:
> It only requires us to ensure /usr is mounted before
> init is started.
>

Which I don't think is a good idea.

> - /usr on a separate filesystem without the use of an initramfs: not
> supported... and no discernable user demand for this.
>

Well, let's say I have a big crash, and I want to recover, and I
need to access /etc/lvm/archive in a single user, with of course
my /usr in a bad state, and I wouldn't be able to mount it for
various reasons. Let's say, an HDD crash, which is very common.

If I need to have /usr mounted before init starts, then I'm more
or less dead, and I'll have to get a recovery CD / USB.

If I don't need /usr, everything is fine, I can boot into single
user mode, and repair.

Guess which situation I prefer?

Now, you tell me: what are the advantage of requiring having
everything in /usr exactly? I really don't get what the advantage is.

On 08/31/2012 03:39 AM, Steve Langasek wrote:
> However, I struggled to formulate a concrete
> scenario where losing support for that last configuration would actually
> make a difference.
>

You must have not read some of my posts then.

> No one in the various threads on debian-devel has presented such a scenario.
> They've all been arguing the straw man that "/usr as a separate fs is not
> supported", which is not what's on the table.
>

Ditto. We did give concrete examples were recovery would be
harder with things in /usr rather than in /.

Also, please make the point into why having stuff in /usr is
to be preferred. Or is it that the *only* argument that you
have is that we are polluted by RedHat crap? If so, why
shouldn't we consider switching to an alternative of udev
like mdev, if its development goes on the right direction,
for Jessie?

Thomas


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Old 08-31-2012, 09:53 AM
Timo Juhani Lindfors
 
Default Stuff from /bin, /sbin, /lib depending on /usr/lib libraries

Thomas Goirand <zigo@debian.org> writes:
> If I need to have /usr mounted before init starts, then I'm more
> or less dead, and I'll have to get a recovery CD / USB.

Not completely. Just boot with break=premount and read /etc/lvm from the
initramfs shell. I've done this several times. The cool part is that you
can also start networking and netcat stuff to/from the machine that
needs to be recovered.


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Old 08-31-2012, 09:57 AM
John Paul Adrian Glaubitz
 
Default Stuff from /bin, /sbin, /lib depending on /usr/lib libraries

On Aug 31, 2012, at 11:26 AM, Thomas Goirand <zigo@debian.org> wrote:

> On 08/31/2012 11:39 AM, Serge wrote:
>> Many (most?) major successes in IT history were about inventing a good
>> standard communication interface to do things. IBM PC was successful
>> because it could be assembled from standard easily accessible components,
>> and was easy to upgrade by just replacing those components with newer
>> ones. That worked so good because there were standard interfaces for
>> devices (ISA, PCI, AGP, etc).
>>
>
> This is quite off topic, but I don't think that's the reason. The reason why
> the PC platform won was because both Comodore and Atari failed because
> of stupid decisions. They were largely superior platforms at the time (both
> software and hardware) though, and a way cheaper.

Yes . Commodore died because their management was utter crap.

They basically killed every successful product they had (like the A500) and replaced them with ones that didn't sell well.

Plus they were stupid enough to let a huge business deal with Sun break who wanted to license Amigas as low-end Unix workstations.

Adrian

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Old 08-31-2012, 10:55 AM
Riku Voipio
 
Default Stuff from /bin, /sbin, /lib depending on /usr/lib libraries

On Fri, Aug 31, 2012 at 05:39:14PM +0800, Thomas Goirand wrote:
> On 08/31/2012 03:39 AM, Steve Langasek wrote:
> > - /usr on a separate filesystem without the use of an initramfs: not
> > supported... and no discernable user demand for this.

> Well, let's say I have a big crash, and I want to recover, and I
> need to access /etc/lvm/archive in a single user, with of course
> my /usr in a bad state, and I wouldn't be able to mount it for
> various reasons. Let's say, an HDD crash, which is very common.

> If I need to have /usr mounted before init starts, then I'm more
> or less dead, and I'll have to get a recovery CD / USB.

How is that different from having a botched / or /boot ? Why do you
think having a separate /usr will make / less prone to HD crashes?
You have / on RAID5 while /usr isn't?

Anyways maintaining a good recovery CD / USB is more worthwile than
keeping supporting a hard drive partitioning scheme that doesn't really
add value for users anymore.

> Now, you tell me: what are the advantage of requiring having
> everything in /usr exactly? I really don't get what the advantage is.

The main advantage is that we wouldn't be having this mail thread.

As there would be no need to ensure there is no dependencies from
/{lib,bin,sbin} to /usr, we wouldn't have the maintainer overhead
and chatter on debian-devel of trying to fix those issues.

Riku


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Old 08-31-2012, 11:33 AM
 
Default Stuff from /bin, /sbin, /lib depending on /usr/lib libraries

On Aug 31, Thomas Goirand <zigo@debian.org> wrote:

> If I need to have /usr mounted before init starts, then I'm more
> or less dead, and I'll have to get a recovery CD / USB.
If this is a concern to you, you can install the grml-rescueboot
package and/or a similar on-disk rescue image which will provide you
with a complete rescue environment.

> If I don't need /usr, everything is fine, I can boot into single
> user mode, and repair.
In some case you can, in some others you cannot.
But if you have a complete bootable rescue environment, which if
slightly tuned is going to be as big as one or two initramfs (IOW,
trivially small), then you are safe against any kind of crashes.

> Now, you tell me: what are the advantage of requiring having
> everything in /usr exactly? I really don't get what the advantage is.
I am not going to argue about this again right now.

--
ciao,
Marco
 
Old 08-31-2012, 02:57 PM
Thomas Goirand
 
Default Stuff from /bin, /sbin, /lib depending on /usr/lib libraries

On 08/31/2012 06:55 PM, Riku Voipio wrote:
> How is that different from having a botched / or /boot ? Why do you
> think having a separate /usr will make / less prone to HD crashes?
> You have / on RAID5 while /usr isn't?
>

Typically, I have / on 2 small RAID1 partitions making the array on the
first
2 HDD (1 or 2 gigs), and /usr on a LVM on a much, much larger RAID array
(I use mostly software RAID1 and RAID10, but in some cases, much bigger
hardware RAID5). So yes, that's my usual server setup.

Also, / is a partition on which almost nothing is read or written, while
the others (eg: /usr, /var, /tmp, swap) are a lot more I/O intensive.
Which means that / is less prone to failure. Often, the 2nd RAID
array gets degraded, but / isn't. So it does make a lot of sense to
setup things this way, and yes, / is less prone to HD crashes this
way (I'm talking from 10 years of experience running about 100
servers this way, so it's not just theory, it's very practical experience).

> Anyways maintaining a good recovery CD / USB is more worthwile than
> keeping supporting a hard drive partitioning scheme that doesn't really
> add value for users anymore.
>

It does add value, as per above.

I'll keep in mind Marco's suggestion of grml-rescueboot which I didn't
know and try in the next following days, it looks cool!

Thomas


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