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Fedora 17 Moves Forward With Unified File-System

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  • Fedora 17 Moves Forward With Unified File-System

    Phoronix: Fedora 17 Moves Forward With Unified File-System

    Fedora 17 is moving forward with plans whereby the entire base operating system will live within /usr by condensing several common directories that have been long-standing to Linux distributions...

    http://www.phoronix.com/vr.php?view=MTA0OTY

  • #2
    Why move / -> /usr? Why not /usr -> / with /usr becoming a symlink to /?

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    • #3
      Originally posted by Aquous View Post
      Why move / -> /usr? Why not /usr -> / with /usr becoming a symlink to /?
      Agreed. +1

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      • #4
        Originally posted by Aquous View Post
        Why move / -> /usr? Why not /usr -> / with /usr becoming a symlink to /?
        Because /usr includes a lot of folders that aren't in /.

        /usr/games
        /usr/libexec
        /usr/local
        /usr/share
        /usr/src
        /usr/x86_64-pc-linux-gnu

        etc

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        • #5
          src, share, local, and include are the normal ones that I see, not sure about games and libexec. In any event, do you spend a lot of time in / where a few extra directories would really bother you? Now that the stuff in /usr will only be in /usr, the grouping will be pretty arbitrary compared to what's sitting directly in /.

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          • #6
            Originally posted by roland View Post
            src, share, local, and include are the normal ones that I see, not sure about games and libexec. In any event, do you spend a lot of time in / where a few extra directories would really bother you? Now that the stuff in /usr will only be in /usr, the grouping will be pretty arbitrary compared to what's sitting directly in /.
            That's not the point. The point is that the directories in / that are being merged into /usr already exist in /usr.

            The same is not true in the other direction -- as I just showed.

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            • #7
              The unified file-system is a good idea and a step into the right direction and I'm looking forward to see the change in a lot more distributions.
              Btw., does someone know what happened to gobolinux? Unfortunately the project seems to be dead. While their file-system structure was certainly controversial, it was a consequent and interesting re-layout imho.

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              • #8
                I think the goal is simply to make /[s]bin and /usr/[s]bin equivalent. You could achieve the same by moving the folders from /usr to /, but you would still need symlinks for compatibility (thus, /usr would remain), so there's really no point.

                Also, see the page linked in the article:

                Myth #11: Instead of merging / into /usr it would make a lot more sense to merge /usr into /.

                Fact: This would make the separation between vendor-supplied OS resources and machine-specific even worse, thus making OS snapshots and network/container sharing of it much harder and non-atomic, and clutter the root file system with a multitude of new directories.
                Last edited by Nobu; 01-27-2012, 03:47 PM.

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                • #9
                  The idea is you could mount an entire new distro onto /usr very easily or use snapshotting from btrfs to allow easier rollbacks

                  If you read the arguments for this you'll see that it's very thought out

                  http://www.freedesktop.org/wiki/Soft...ForTheUsrMerge

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                  • #10
                    Myth #11: Instead of merging / into /usr it would make a lot more sense to merge /usr into /.
                    Fact: This would make the separation between vendor-supplied OS resources and machine-specific even worse, thus making OS snapshots and network/container sharing of it much harder and non-atomic, and clutter the root file system with a multitude of new directories.
                    I suggest that people at least TRY to read the FAQ.

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                    • #11
                      Folks please at least read the explanation before suggesting or complaining.

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                      • #12
                        Unified File-System

                        This seems to make a lot of sense, and I hope it works out well, and is adopted by all Linux distro's.

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                        • #13
                          I was initially against this and I felt that not enough consideration was being given to why they were split in the first place. I have now read this and hastily switched sides.

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                          • #14
                            I've read the freedeskop wiki, I've read the 'explanation' about small disks and what not.
                            The historical justification for a /bin, /sbin and /lib separate from /usr no longer applies today. (More on the historical justification for the split, by Rob Landley) They were split off to have selected tools on a faster hard disk (which was small, because it was more expensive) and to contain all the tools necessary to mount the slower /usr partition. Today, a separate /usr partition already must be mounted by the initramfs during early boot, thus making the justification for a split-off moot. In addition a lot of tools in /bin and /sbin in the status quo already lost the ability to run without a pre-mounted /usr. There is no valid reason anymore to have the operating system spread over multiple hierarchies, it lost its purpose.
                            I don't ever heard of that being the reason for the split. Faster slower disks? The 'explanation' actually puts it as
                            "Ken and Dennis leaked their OS into the equivalent of home because an RK05 disk pack on the PDP-11 was too small"
                            Which makes some sense I suppose, and may be true back then, but found more adequate meaning later. I'm sure everybody has forgotten abou the 'FHS' but it does still exist. This what it has to say about /bin.
                            Chapter 3. The Root Filesystem
                            Purpose

                            The contents of the root filesystem must be adequate to boot, restore, recover, and/or repair the system.

                            To boot a system, enough must be present on the root partition to mount other filesystems. This includes utilities, configuration, boot loader information, and other essential start-up data. /usr, /opt, and /var are designed such that they may be located on other partitions or filesystems.

                            To enable recovery and/or repair of a system, those utilities needed by an experienced maintainer to diagnose and reconstruct a damaged system must be present on the root filesystem.

                            To restore a system, those utilities needed to restore from system backups (on floppy, tape, etc.) must be present on the root filesystem.
                            No myth here, a mere 'fact' if you may call the FHS that. And it makes sense. Yes, an initramfs can fulfil this task. But I guess the sloppyness of fedora would mean the initramfs would grow to 450mb in a few years time ..

                            Myth #9: The /usr split is useful to have a minimal rescue system on the root file system, and the rest of the OS on /usr.

                            Fact: On Fedora the root directory contains ~450MB already. This hasn't been minimal since a long time, and due to today's complex storage and networking technologies it's unrealistic to ever reduce this again. In fact, since the introduction of initrds to Linux the initrd took over the role as minimal rescue system that requires only a working boot loader to be started, but not a full file system.
                            So because fedora's / is ~450MB it is fact that it hasn't been minimal? On my gentoo server it's about
                            Code:
                            du -d 1 -h / -x
                            16K     /lost+found
                            4.0K    /home
                            4.0K    /opt
                            22M     /lib64
                            4.0K    /var
                            11M     /sbin
                            16M     /boot
                            4.0K    /mnt
                            0       /dev
                            2.6M    /lib32
                            0       /sys
                            4.0K    /media
                            11M     /bin
                            13M     /etc
                            4.0K    /usr
                            108K    /chroot
                            0       /proc
                            11M     /root
                            4.0K    /tmp
                            86M     /
                            So that's about 75MB (/root has some stuff i need to move). Actually, 68MB as /etc contains a .git tree worth 7MB. Pretty reasonable and minimal. And it can do everything it is supposed to do to recover my system. So this says more about fedora, than about linux in general, or is gentoo the only one that keeps it as it should?

                            And I do actually have an initramfs, it contains mdadm to bring up my raid1 and raid5's since it is no longer supported to have the kernel do it.

                            Myth #10: The status quo of a split /usr with mounting it without initrd is perfectly well supported right now and works.

                            Fact: A split /usr without involvement of an initrd mounting it before jumping into the root file system hasn't worked correctly since a long time.
                            Lie. Sure, in fedora it doesn't work, probably not in ubuntu either. But on my gentoo box, it works perfectly fine, to recover and repair the system of course, which what this split is for!! Even if my initramfs fails and i only have the kernel, I can still boot from half my raid1 and still repair my system!


                            So all in all, this move seems more like 'Fedora's / is a mess and isn't properly split as it should, lets just move everything to /usr and where it should be anyway, and do our own thing.'

                            I'm surprised nobody mentioned the FHS in the 'explanation' mailing-list thread. Also, I'm supprised the mentioning of /usr/local and /opt. As far as I understood, from the FHS obviously, is that /usr/local where applications that where installed locally on the host, say if /usr where on nfs. /opt was for 3rd party (closed src) applications and other 'add-ons'. I can actually even see an /opt/local, if /opt would have been an nfs share, but 1 system would be allowed to install a specific 3rd party package.
                            Last edited by oliver; 01-27-2012, 06:19 PM.

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                            • #15
                              And the other guys...

                              What do Debian and SUSE people think of this?

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