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Debian still having trouble with merged /usr

lwn.net

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Re: Debian still having trouble with merged /usr

#241

Post by JoshTriplett »

ssl232 wrote: post #43
pabs3 wrote: post #36

Earlier quoted context omitted.

There is a comment on the LWN article about that: https://lwn.net/Articles/890306/ > First, technical challenges: HURD tried to move from /usr to / and had quite a bit more trouble with it, and that trouble warned against trying it on a larger scale. It's much easier to move from / to /usr than from /usr to / ; fewer things break. > Second, consolidation: moving into /usr gives us a single directory containing all fi…

The A/B system upgrade idea is intriguing. And kinda painfully obvious, in hindsight. Why don't the distros that have merged /usr do that already?

The latest version of systemd has a tool for doing exactly that.

Re: Debian still having trouble with merged /usr

#242

Post by nitrogen »

felixgallo wrote: post #221
PaulDavisThe1st wrote: post #203

Earlier quoted context omitted.

Rob Landley doesn't agree: http://lists.busybox.net/pipermail/busybox/2010-December/074...

Peace to Rob, but disagree with his recollection and the motivation. This was a very active topic in the early commercial Unix days as POSIX etc. were being formulated. It was very common to keep a tar backup of / and to separate out your /usr mount not because you didn't have space on /, but because you wanted to be able to lose/upgrade/etc. / without impacting /usr, and perhaps to move/copy /usr to another machine.…

Both recollections can be correct. Sometimes an idea that starts for one reason is kept for different reasons.

Re: Debian still having trouble with merged /usr

#243

Post by PaulDavisThe1st »

felixgallo wrote: post #221
PaulDavisThe1st wrote: post #203

Earlier quoted context omitted.

Rob Landley doesn't agree: http://lists.busybox.net/pipermail/busybox/2010-December/074...

Peace to Rob, but disagree with his recollection and the motivation. This was a very active topic in the early commercial Unix days as POSIX etc. were being formulated. It was very common to keep a tar backup of / and to separate out your /usr mount not because you didn't have space on /, but because you wanted to be able to lose/upgrade/etc. / without impacting /usr, and perhaps to move/copy /usr to another machine.…

I started using Unix (as a sysadmin and systems programmer) in about 1986, and my recollection is closer to Rob's.

1. Never used tar(1) for backups till much later, always dump(1),

2. Never wanted to separate backups or upgrades of / and /usr, but always wanted and needed to do that for /usr/local and wherever we put home dirs in those days (which I don't recall right now).

3. The / and /usr thing was definitely explained to me in terms of disk space, more by comparison with the VMS system I was also managing which had 1MB drives. But I was too late to have "been there".

Re: Debian still having trouble with merged /usr

#244

Post by slim »

hyperdimension wrote: post #215
Beltalowda wrote: post #188

Earlier quoted context omitted.

> It is because on old Unix systems there frequently wasn't enough space to store /usr on the root disk. It was really a single system in 1971 that kicked off this trend. Originally /usr was for user files, like /home is today (do you'd have /usr/dmr, /usr/ken, etc.) / and /usr were two physical disks, and at some point the / disk (a 1 or 2MB disk IIRC) was full to they put some things from /bin in /usr/bin as a hack…

Is that also where /usr/share got its name for application data? Data that's shared among the rest of the users, as opposed to in their respective homedirs?

I think /usr/share is linux specific. so much later

Re: Debian still having trouble with merged /usr

#245

Post by nitrogen »

IntelMiner wrote: post #231
nyuszika7h wrote: post #219

Earlier quoted context omitted.

This one is relatively maintained, for example: https://github.com/pyroscope/pyrocore

Last release was all the way back in 2017?

I'd be perfectly happy to use software whose last release was in 1987 if it gets the job done and I can isolate it from the network.

Re: Debian still having trouble with merged /usr

#246

Post by zh3 »

rektide wrote: post #225
zh3 wrote: post #198

I've always liked the /usr distinction, with systems set up so they will at least boot without /usr mounted (at an absolutely minimum, a statically linked /bin/sh is enough to get a command prompt). This is particularly valuable for setups where a large number of PCs can mount /usr read-only from a remote server (we run quite a number of diskless x86 amd ARM systems like this).

Bind mount your small system's /usr to /lower, mount your bigger /upper, and use overlayfs to combine them. Looking forward ro some blog posts discussing how to support this use case; it's a good one. I think usr-merge is so much more managable though that it's totally worth doing.

Must admit I'm surprised there don't seem to be more users out there doing exactly this. Makes installing a new program for everyone instant (put it in /usr, now available to all) while allowing personal customisations with the ability to reset the system to a pristine state in a second. Esp. combined with diskless, the computer hardware becomes irrelevant/disposable - just grab a fresh one, boot the same image and carry on (or boot your personal image at a hot desk).

Re: Debian still having trouble with merged /usr

#247

Post by nitrogen »

mwcampbell wrote: post #103
andrepd wrote: post #96

Earlier quoted context omitted.

Not only is that impractical (how can you reliably filter blindness before birth? I suppose you could test babies eyesight at birth and kill them if they're blind?), but what about the people who get blind during their lives? They are the vast majority of cases of blindness! It seems very odd to propose that the solution to a problem is to liquidate all people who suffer from that problem.

Fair points. Sometimes it just seems like it's futile to advocate for accommodations everywhere. I should be thoroughly used to it by now, though.

Everywhere? Probably not. Enough to live a fulfilling life? Absolutely. Everyone deserves that much.

Re: Debian still having trouble with merged /usr

#249

Post by bigbillheck »

PaulDavisThe1st wrote: post #205
mwcampbell wrote: post #116

Earlier quoted context omitted.

One can only be exposed to so much backlash from seemingly reasonable people before wondering if they're actually right.

"Seemingly reasonable" is a poor place to start. It's somehow similar to the way so many of us expect actually evil people to somehow come with horns or other evil-indicating visual accessories. The reality is that evil people wear suits, and jeans, and shorts and hats and look just like the non-evil people. So it is with "reasonable". The fact that someone can phrase their objections to accessibility that doesn't ma…

I saw a bit of rhetoric a while back about how it's not "disabled people and non-disabled people", it's really "disabled people and not-currently-disabled people."

Between spending several months on crutches ten-ish years ago and helping care for several elderly relatives, I'm a believer.

Re: Debian still having trouble with merged /usr

#250

Post by mcguire »

nickcw wrote: post #89

Just in case anyone is wondering why we had (or used to have) /bin and /sbin directories as well as /usr/bin /usr/sbin here is my understanding of it. It is because on old Unix systems there frequently wasn't enough space to store /usr on the root disk. Therefore /usr was a separate disk which might not be available during boot. This meant that you needed to put all the binaries you needed for boot in /bin and /sbin…

Old Unix guy here: That is my understanding as well.

But then the question becomes, why not get rid of /usr?

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