Linked by Thom Holwerda on Mon 30th Jan 2012 20:39 UTC
General Unix Finally something really interesting to talk about. If you've used UNIX or any of its derivatives, you've probably wondered why there's /bin, /sbin, /usr/bin, /usr/sbin in the file system. You may even have a rationalisation for the existence of each and every one of these directories. The thing is, though - all these rationalisations were thought up after these directories were created. As it turns out, the real reasoning is pretty damn straightforward.
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RE[2]: why not / instead of /usr
by phoenix on Mon 30th Jan 2012 21:32 UTC in reply to "RE: why not / instead of /usr"
Member since:

Uhm, why would snapshotting / be any harder than snapshotting /usr? Snapshots happen at the filesystem level, and if everything else is a separate filesystem (/home, /var, yadda yadda) then / is a filesystem all to itself ... so why would snapshotting it be hard?

And if you want to talk about polluting the / directory, have a look at all the virtual filesystems that need mountpoints. Just have a look at the output of "mount" on a Linux system these days. There's a good 8 or so virtual filesystems that all need mountpoints in / (/proc, /sys, /dev, various tmpfs, etc).

Edited 2012-01-30 21:33 UTC

Reply Parent Score: 2

Aristocracies Member since:

You're not understanding the problem domain here, this is more about maintaining a collection of machines that all share the same set of binaries at the same patch level, etc. Snapshotting and sharing / includes things such as /etc and potentially /var which would have to be excluded in a lot of cases since they're not generic enough to want to share across machines. There's plenty of situations where you will want to maintain the binaries separate from the configuration, such as hosting scenarios.

But hey, you know, no one working on Solaris or Fedora or anything has put any thought into this at all and they're just doing it for kicks really.

Edited 2012-01-30 21:41 UTC

Reply Parent Score: 1

phoenix Member since:

I understand the problem domain perfectly. I support over 3000 diskless Linux stations as my day job. And every day I fight with the asinine Linux directory structure (coming from a FreeBSD background where things make sense).

We share out / via NFS, including /etc. And /usr, /var, /home are also shared via NFS. And other filesystems.

If you're going to amalgamate directories, then leaving / with a bunch of empty directories and symlinks is not the way to do it.

I've read all the mailing list threads about this project, and all of the reasonings given boil down to "this is how we're doing it, deal with it". There's no actual, good, solid, evidence-based reasons given.

Yes, Linux filesystem hierarchy is a mess. But this doesn't do anything to help fix that.

Reply Parent Score: 1