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Fedora 16 To Use Btrfs Filesystem By Default

Posted by timothy on from the taking-a-bold-line dept.

dkd903 writes "According to proposals for Fedora 16, Btrfs will be the default filesystem used in that release. The proposal has been approved by the Fedora Engineering Steering Committee. In Fedora 16, the switch from EXT4 to Btrfs will be a 'simple switch' — it means that major Btrfs features such as RAID and LVM capabilities will not be forced onto users."

50 of 198 comments (clear)

  1. Cool. by Anonymous Coward · · Score: 3, Funny

    Can't wait to turn all my files into butter.

    1. Re:Cool. by jetole · · Score: 5, Insightful

      Turn your files into butter is right. Though I don't use Fedora, I was interested to look into btrfs again when I read this post on slashdot.

      Much to my surprise, directly from the main btrfs wiki: "Note that Btrfs does not yet have a fsck tool that can fix errors. While Btrfs is stable on a stable machine, it is currently possible to corrupt a filesystem irrecoverably if your machine crashes or loses power on disks that don't handle flush requests correctly. This will be fixed when the fsck tool is ready."

      Why would RedHat choose such a file system that does not have basic support for recovery of a file system after a system crashes? This has been an essential part of file systems since the as far back as I can remember.

    2. Re:Cool. by jetole · · Score: 3, Insightful

      "a very small risk"? Have you never had a system crash that you have had to reboot? Have you never had to run fsck to scan and correct a disk? Everyone else I know who uses Linux has done both multiple times. This particular "shiny new toys", as you put it, is not production ready if it does not contain fsck capabilities and according to it's authors it does not. When I say "production ready", I am not referring to whether or not it's stable enough to run a production server farm but I mean whether or not it is capable to handle a Linux desktop system that is not designated for beta testing only. I would be happy to run btrfs when everything is complete but right now the authors of btrfs say that a nessecary component for generic system failure issues is not yet complete.

    3. Re:Cool. by jjohnson · · Score: 3, Insightful

      You get the reliability you select. All you need to do to avoid this issue with brtfs is 1) use ext4 instead, or 2) use a hard disk that doesn't lie about whether or not it's buffering.

      Fedora is not production ready even in the sense of a daily use desktop with data that can't be recovered from backup, even without this problem. It's explicitly a testbed distro, and always has been.

      --
      Anyone who loves or hates any language, platform, or manufacturer, doesn't know what they're talking about.
  2. Re:Btrfs features forced on users? by Denogh · · Score: 3, Informative

    Oh wait... I'm a dummy that can't read.

  3. Rollback system changes by EponymousCustard · · Score: 2

    Does this mean we are a step closer to the possibility of snapshotting system states and rolling back to before a bunch of updates were installed?

    1. Re:Rollback system changes by rwa2 · · Score: 2

      Sure, you can sort of do that with LVM now.

      What doesn't work with LVM, unfortunately, is using snapshots that allow you to "roll forward" if the system updates work out all right and you want to accept the updates into your main volume :-/

    2. Re:Rollback system changes by BrentH · · Score: 4, Informative

      The fact that you don't see how a filesystem integrated snapshot function could make a difference tells me that you've never used anything like that. And your alternative of managing partitions and 'backups' tell me that you certainly have never tried to manage anything like this on a scale beyond your own machines.

      Let me tell you, ZFS-like snapshots are the best improvement to computing since proper multi-user systems. It makes managing file security and integrity so, so much easier, and at almost no cost. (and by ZFS-like I mean with the ease and speed of ZFS, I've not yet seen much numbers on BTRFS performance)

    3. Re:Rollback system changes by EponymousCustard · · Score: 4, Interesting

      Snapshot takes minimal disk space compared to a backup. Plus you would need to backup the entire / tree to rollback changes made by a yum update.

    4. Re:Rollback system changes by Rich0 · · Score: 2

      I believe in btrfs that a snapshot is itself a mountable structure, so in theory all you have to do is do a snapshot called "previous_foo" and then install your changes, and if it doesn't work boot with (real_)root= on your kernel line.

      Not a whole lot needs to actually come together unless you want it all automated. Then again, I run gentoo so my grub.conf is hand-configured anyway. :)

    5. Re:Rollback system changes by Bob+Loblaw · · Score: 3, Insightful

      There was already a yum plugin for this (yum-plugin-fs-shapshot) as far back as F13 as mentioned here: http://fedoraproject.org/wiki/Btrfs_in_Fedora_13

      It will do an automatic btrfs snapshot of affected filesystems before every yum transaction so that you can go back to whatever point you want. Also, since it is partition dependent, you can rollback your system partition and not undo changes you may have made to your home directories if you have those on different partitions.

      btrfs is quite powerful but I have found that the user/GUI tools have not come up to speed yet. I have been using btrfs from my F15 netbook and it seems to have caused no issues so far. However, enabling transparent compression and any tweaking has entailed editing /etc/fstab (never a thing to do lightly) and command lines.

      Hopefully some of the GUI disk management tools will start to make available some of the capabilities of btrfs.

    6. Re:Rollback system changes by grumbel · · Score: 4, Interesting

      Use an incremental backup?

      That would still mean a shitload of data to copy around. The point of copy-on-write snapshots is that the cost of copying your whole file system is essentially zero.

      To make an normal application analogy: Of course you don't really need Undo/Redo, you can just "Save As" your file at any step of the way, but Undo/Redo makes things a hell of a lot more convenient and more importantly it helps you in those situation where you would have considered a "Save As" to be to much work to bother with and thus have no backup to fall back to.

    7. Re:Rollback system changes by TheRaven64 · · Score: 2
      Nexenta does this already. They have an apt-clone utility that wraps apt-get and ZFS snapshots. It takes a snapshot, then does the upgrade. If you don't like it (e.g. stuff breaks), you roll back to the snapshot. If you do, then you just delete the snapshot and continue.

      We've already heard folks shout "layering violation" at basic parts of ZFS itself

      And the person who said this clarified it saying that it wasn't a criticism. It's also wrong. ZFS has very clean layering, it just doesn't put the layers in the same place as System V.

      --
      I am TheRaven on Soylent News
  4. still not using grub2? by drinkypoo · · Score: 3, Interesting

    Summary: We like it when you test new stuff for us, and our customers are clamoring for this filesystem in RHEL, so we're going to let you try it out on Fedora for a while and experience the hiccoughs. And speaking of new stuff, we're going to finally get around to moving up to grub2 like everyone else, which we haven't bothered to implement even though it's much better, and we allegedly like new stuff.

    --
    "You're right," Fisheye says. "I should have set it on 'whip' or 'chop.'"
    1. Re:still not using grub2? by BreezeC · · Score: 2

      Maybe the boss redhat don't like grub2.

    2. Re:still not using grub2? by grasshoppa · · Score: 2, Informative

      Yes, and? I thought it was well known that fedora is the test bed for RHEL.

      --
      Mod me down with all of your hatred and your journey towards the dark side will be complete!
    3. Re:still not using grub2? by drinkypoo · · Score: 2

      Yes, and therefore "When it comes to adopting the newest technologies, Fedora is always at the front among the major Linux distributions" is a dirty lie. It should be "When it comes to convincing fools to beta-test RHEL for us, Fedora is the shiznit!" What does "major Linux distributions" mean, anyway? I'd give that to Gentoo, which often makes functionality available very early.

      Fedora is of course at the forefront of adopting the newest technologies developed by Red Hat. Some of what they have written has been very nice. I don't want to take anything away from them. I only find this blog entry to be an inane piece of marketfluff.

      --
      "You're right," Fisheye says. "I should have set it on 'whip' or 'chop.'"
    4. Re:still not using grub2? by Rich0 · · Score: 4, Informative

      So, I'm a Gentoo Dev and I'd qualify that statement a little. Gentoo tends to make a lot of stuff available very early, but it doesn't tend to go all-in with experimental stuff for the base user experience. The default Gentoo stable experience is legacy Grub, for example. And Gentoo hasn't bought into Unity/Systemd/etc. Although, there is talk of adding systemd to the list, and Chrome OS is a Gentoo-based distro that uses unity - so clearly it can be done.

      Gentoo tends to be about giving users a default experience that is reasonably stable, but making it a lot easier for users to branch out and try different things, while still keeping much of the update automation in place.

      Gentoo tends to be less about the polished desktop experience, so I suspect we'll always lag something like Ubuntu in that regard - at least when it comes to ripping apart everything and trying something new.

    5. Re:still not using grub2? by Rich0 · · Score: 2

      It is, but keep in mind that there are many bleeding edges.

      You could be running bleeding edge postfix, or you could be running bleeding edge sendmail - the distro doesn't care which.

      You could be running bleeding edge KDE or Gnome - again we don't care.

      You could be running the default openrc, or perhaps one day you could be running systemd (right now we care - some would like to change that).

      There is a default experience if you follow the guidebook and don't mess with certain flags/packages/etc. It can be stable or bleeding-edge. However, to do the really exotic stuff you need to go looking.

      The typical experimental user tends to stick with fairly stable stuff for 95% of the system, and go crazy with the other 5%. That lets them do something exotic without having to play whack-a-mole with all the bugs.

  5. mdadm woes begone? by Hylandr · · Score: 2

    I was handed a block of drives that had been in a server recently with software raid and asked to rebuild the array and recover the data. This had been assembled with mdadm. Will this change make such recovery a non issue with snapshots and the like, providing of course the array had been running btrfs?

    - Dan.

    --
    ~ People that think they are better than anyone else for any reason are the cause of all the strife in the world.
    1. Re:mdadm woes begone? by guruevi · · Score: 4, Informative

      Much like ZFS, mdadm will simply be replaced with another set of commands. If a drive crashes and the array is not correctly set up, you will also lose data and it will be a pain in the butt to repair it (I've done ZFS recovery of a corrupted pool, no fun). Again, RAID (or any software checksum based alternative) is not a backup. You should have hourly/daily/weekly snapshots and backups depending on the importance of your data.

      The good thing about ZFS and Btrfs vs RAID is that they fail graciously. Most of the time it will be able to indicate which files are corrupt, allow you to mount read only and at least copy portions of it over so there is some more intelligence built-in than a simple XOR but that's just the progression of technology.

      --
      Custom electronics and digital signage for your business: www.evcircuits.com
    2. Re:mdadm woes begone? by Rich0 · · Score: 3, Interesting

      I think the bigger issue with btrfs vs mdadm and ext4 will just be maturity. Btrfs repair tools just haven't evolved to the same place the other tools are at, but there is no fundamental reason why they won't eventually make it there.

      As you say btrfs has the advantage that it knows something about how the space is used, so if space was just free it could just nuke it and not worry about trying to salvage garbage data. It could also use free space to leverage recovery. And, the concept of COW means that strips are less likely to be in a transitory state of having meaningful data partially overwritten by other meaningful data, since the filesystem would first try to write the stripe over unused space leaving a fully intact backup if it is interrupted and the array is already degraded/etc.

      The last time I tried test-converting an existing ext4 into a btrfs on RAID it paniced, but it has been almost a year now...

  6. Sources for this? by Dan+Dankleton · · Score: 5, Informative

    Surely there could be a better source for this than one blog post (I know, high UID so I must be new here.)

    But linking to something like http://fedoraproject.org/wiki/Features/F16BtrfsDefaultFs or http://thread.gmane.org/gmane.linux.redhat.fedora.devel/149196/focus%3D149215 to lend a little authority might have been nice...

    1. Re:Sources for this? by Lunix+Nutcase · · Score: 3, Insightful

      But how does that drive ad clicks for digitizor if one links to the official source? Silly you.

  7. I wonder if they have a working fsck yet? by Thrakkerzog · · Score: 3, Insightful

    In the long run btrfs will be good to have, especially with solid state drives gaining popularity. Even embedded devices can easily have multi-gigabyte flash chips, and btrfs would be faster and more efficient on these when compared to jffs2 and yaffs.

    1. Re:I wonder if they have a working fsck yet? by Zoidmann · · Score: 4, Informative

      It seems like they haven't: https://btrfs.wiki.kernel.org/index.php/FAQ#When_will_Btrfs_have_a_fsck_like_tool

      Hopefully they know something about it being released soon since making the decision to use it.

    2. Re:I wonder if they have a working fsck yet? by Just+Some+Guy · · Score: 2

      Is there a need an fsck? For example, ZFS doesn't have one and I haven't heard of anybody working on it (or of anybody actually wanting one).

      --
      Dewey, what part of this looks like authorities should be involved?
    3. Re:I wonder if they have a working fsck yet? by cratermoon · · Score: 5, Informative

      It says right here on the btrfs wiki: "While Btrfs is stable on a stable machine, it is currently possible to corrupt a filesystem irrecoverably if your machine crashes or loses power on disks that don't handle flush requests correctly. This will be fixed when the fsck tool is ready. "

      So I'd say yah, that's a pretty important piece to be missing if you're talking about making it the default for a distro, even one as free-wheeling as Fedor.

    4. Re:I wonder if they have a working fsck yet? by bill_mcgonigle · · Score: 5, Interesting

      Is there a need an fsck? For example, ZFS doesn't have one and I haven't heard of anybody working on it (or of anybody actually wanting one).

      Um, yeah, read zfs-discuss. There are helpful folks on there who help people recover their ZFS volumes, but having a tool to do it would be much better.

      fsck for ZFS or btrfs means something different than it does for ext* but it's still needed. I just had a client's new 18TB ZFS zvol go TU when the power failed and the UPS->host communication wasn't properly connected. Fortunately it wasn't very important and the important zvol wasn't active when the power failed.

      btrfs will be better than ZFS for many use cases once the fsck is stable. For others ZFS will remain better, but you better have battery-backed disk cache or a monitored UPS (neither of which are appropriate requirements for large swaths of the Fedora user base).

      --
      My God, it's Full of Source!
      OUTSIDE_IP=$(dig +short my.ip @outsideip.net)
    5. Re:I wonder if they have a working fsck yet? by Mullen · · Score: 3, Informative

      I have seen this issue with other filesystems. It comes from when the hard drives *lie* to the RAID or I/O controller stating that they don't buffer or are not buffering when in reality, they are. It's really frustrating since you can't trust the drives have written out the data.

      --
      Linux O Muerte!
    6. Re:I wonder if they have a working fsck yet? by maskedbishounen · · Score: 3, Insightful

      This. I run btrfs on my home file server and lost a half year of data due to a power outage corrupting the filesystem. Afterwards I was looking around for its fsck utility only to find it does not yet exist. Btrfs may be the way of the future, but as is, it's still too soon.

      --
      "An infinite number of monkeys typing into GNU emacs would never make a good program."
    7. Re:I wonder if they have a working fsck yet? by nairnr · · Score: 2

      Well, ZFS has scrub which goes through and verifies all checksums, for mirror or raidz it repairs and discrepancies so it is fsck like.

  8. Re:But... btrfs isn't stable by MrHanky · · Score: 4, Insightful

    It makes perfect sense. Btrfs won't get stable for RHEL unless it's beta tested in Fedora first.

  9. My experiences with btrfs by Gaygirlie · · Score: 3, Interesting

    For some reason I'm getting really low performance on btrfs, both on a single disk and on raid1 configurations. I have tried with -nodatacow and with and without -compress, but it seems it doesn't have any effect. Also, I have 90 gigabytes of free space on Storage1 but I get drive full error when I try to write there. Rebalancing it didn't fix the issue. The btrfs command-line tool is, well, rather incomplete and somewhat buggy, like e.g. when I query 'btrfs fi df /media/Storage2' -- with Storage2 being the raid1 pool -- it reports the size and usage of the smallest disk on it, not the whole thing. I don't understand why. I also have had some filesystem corruption which caused me to lose quite a bit of data, and again the only way to fix it was rebalancing the whole thing which takes the whole damn day.

    I do understand that it's a filesystem that's still under development, but the tools atleast need a lot more work. They're just too incomplete at the moment. I'm not really sure pushing it as the default filesystem for end-users is a good idea yet.

    1. Re:My experiences with btrfs by arth1 · · Score: 3, Informative

      . The btrfs command-line tool is, well, rather incomplete and somewhat buggy, like e.g. when I query 'btrfs fi df /media/Storage2' -- with Storage2 being the raid1 pool -- it reports the size and usage of the smallest disk on it, not the whole thing. I don't understand why.

      With RAID 1 (simple mirroring), your volume is limited to the smallest of the components. A 40 GB and a 2 TB drive put together yields a 40 GB RAID 1 volume.

    2. Re:My experiences with btrfs by arth1 · · Score: 3, Informative

      With RAID 0 you get twice the amount of the smallest unit.
      Using a 40 GB and an 2 TB HD will give you an 80 GB RAID 0.

    3. Re:My experiences with btrfs by Rich0 · · Score: 2

      Does btrfs actually stripe like this, or does it simply keep a copy on two volumes for RAID1, and spread data around for RAID0?

      You can tell btrfs to even keep two copies on the same volume if you want, I think.

      They call it RAID, but I don't think it is really the same thing. The RAID5-like features and reshaping don't exist yet (the last time I checked). Then again, maybe it supports both modes of operations - if there is one thing about btrs is that it has a million optional features.

  10. What about fsck support? by edeefelt · · Score: 2

    What about fsck support? The last time I checked, btrfs does not support this important feature to allow recovering from hard disk issues.

    1. Re:What about fsck support? by caseih · · Score: 2

      I've ran BtrFS's arch rival, ZFS for years, and I have never ever had to fsck the disk, even after power outages and crashes (yes Solaris crashes rather spectacularly sometimes). In theory a good file system should always be in a consistent state and never require fscking. Of course you could mean trying to fsck a disk when a hard drive starts failing, but I still don't see how that is useful; fscking a failed drive might just stir the data more. I'll settle for being able to pull off as much data as I can, fsck or no fsck.

  11. Re:Is the disk format fixed? by Carewolf · · Score: 2

    Yes, it was officially fixed in 2.6.32 or something like that. They keep adding more features and improving it, but the format is supposed to be fixed by now.

    Anyway. I don't know if default is a good idea, but even Debian offered btrfs as an option when I installed it on my new laptop last month. It is hardly cutting edge anymore ;)

  12. Re:Btrfs features forced on users? by arth1 · · Score: 5, Informative

    Pretty sure default filesystem != mandatory. They're not going to suddenly drop support for ext*.

    No, but you may have to know how to get it.
    If you install from a LiveCD, which is the default method of install, and the only one you'll see unless you dive deep down on the Fedora site, you have to use the file system they give you. You can change partitioning and much else, but not the file system type. If you do, the installation will fail, telling you that you have to use the same file system as the CD image.

    To get an image that lets you choose the file system without erroring out if you do, you have to (at present):
    - Instead of "Download Now", click "More option"
    - Instead of one of the many options listed there, click "All download methods" hidden on the bottom right.
    - Choose one of the packages under "Install Media" section.

    If you don't, you can, at present, choose any file system you want, as long as it's ext4. Presumably, with F16, it will be btrfs.

    This jumping through hoops seems to be deliberate by Fedora to get people to not use the full install DVDs, but install through a LiveCD instead.

    As I need extended metadata support for Samba to support full CIFS compatibility including advanced permissions, there's really only one performance file system to choose: xfs

    Btrfs won't be touching my machines until it's forked away from Oracle.

  13. Availability Notice by mgmartin · · Score: 4, Insightful
    Quoted from man mkfs.btrfs on Fedora 15.

    ...Btrfs is currently under heavy development, and not suitable for any uses other than benchmarking and review.

    That sure limits the uses of a default Fedora installation.

    1. Re:Availability Notice by Gothmolly · · Score: 2

      You do know what Fedora is supposed to be, right ?

      --
      I want to delete my account but Slashdot doesn't allow it.
  14. Hierarchical File System? by drunkahol · · Score: 3, Interesting

    I'd like to see btrfs implement a proper block tiering system. They're doing something for storing "hot" blocks on SSD, but what about giving us the full monty? Where I can rank storage types myself, assigning a different cost to each type. Hotest blocks in RAMdrive (battery backed of course), next step down fast SSD and then slower SSD, followed by Fibre, SAS, SATA and finally tape. Yes tape. Just create snapshots as backups. These blocks then sit there and drift down to tape storage when required.

    Funny how this has all been done before when disks were really slow. I suppose it's the big gap of incredibly fast SSD's (compared to mechanical) that's resurrecting these ideas. With this done, btrfs could be stuck in as a relatively cheap SAN/NAS solution. All done in a big tower case in my loft.

  15. Re:Fedora is essentially RHEL beta by mlts · · Score: 4, Informative

    ZFS still has a lot btrfs doesn't:

    64 bit CRC support so disk corruption is caught.
    RAID 5/6
    Block level deduplication
    Encryption

    ZFS also replaces the LVM layer, making write performance on raid-Z a lot better than a filesystem + LVM layer.

    This isn't to say btrfs is bad, but until dedupe is added, it will be a generation behind the competition.

  16. Re:Fedora is essentially RHEL beta by toby · · Score: 2

    "64 bit CRC"? No. ZFS uses 256 bit checksums for each block.

    Also, ZFS does not implement RAID-5, RAID-6 or any of the conventional RAID modes; but it has "RAID-like" modes (e.g. mirrored vdev, RAID-Z, RAID-Z2).

    --
    you had me at #!
  17. Re:Fedora is essentially RHEL beta by mlts · · Score: 3, Interesting

    Thanks for the correction, as that definitely is a notable difference.

    Now, if we can get a filesystem that supports autotiering (where it knows which array is SSD, which is spindles and places data accordingly due to times accessed), that would be great. Outside of EMC's offerings, I don't know any really available.

  18. Re:This is why I left Red Hat Behind by mu51c10rd · · Score: 2

    The fragmentation already exists. Need a stable, supported release? Use RHEL. Need to use it without the Red Hat strings attached but still have the stability? Use CentOS. Want the hobbyist bleeding edge? Use Fedora.

  19. Re:Btrfs features forced on users? by m50d · · Score: 2
    Just OOI, what's wrong with reiserfs or JFS?

    /currently running FreeBSD for the sake of ZFS, because it's the only way to not lose data when hard disks die.

    --
    I am trolling
  20. Re:Btrfs features forced on users? by bingoUV · · Score: 2

    FYI, Fedora doesn't support jfs. First, you have to pass a kernel argument "jfs" to make fedora even run a JFS / or /boot. Even then, jfs is not presented as option for /, /home or any other mount point.

    I've been using jfs on Fedora by
    1. installing with ext4
    2. boot into it
    3. install jfsutils
    4. backup the files
    5. create a jfs file system
    6. copy files on jfs file system
    7. edit grub.conf and add jfs kernel argument.

    jfs bugs are rejected by bugzilla.

    --
    Bingo Dictionary - Pragmatist, n. A myopic idealist.