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Thread: Ubuntu 12.10 File-Systems: Btrfs, EXT4, XFS

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    Default Ubuntu 12.10 File-Systems: Btrfs, EXT4, XFS

    Phoronix: Ubuntu 12.10 File-Systems: Btrfs, EXT4, XFS

    For those curious about the file-system performance of Ubuntu 12.10, here are some benchmarks from Quantal's Linux 3.5 kernel with the EXT4, XFS, and Btrfs file-systems.

    http://www.phoronix.com/vr.php?view=17890

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    Interesting to the btrfs doing very well with threaded I/O does that make it ideal for SSDs?
    Are there stabel fsck tools for btrfs available already?

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    Quote Originally Posted by blackout23 View Post
    Interesting to the btrfs doing very well with threaded I/O does that make it ideal for SSDs?
    Are there stabel fsck tools for btrfs available already?
    BTRFS has an SSD mount option which changes some of the underlying logic. To date, I have not seen a compelling set of benchmark results to call it faster than without the mount option on an SSD.

    There are tools for BTRFS, including fsck. I do not know that I would call them stable (It's a relative term), nor do I believe that fsck is as essential as it was with the previous generation of filesystems.

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    Quote Originally Posted by russofris View Post
    BTRFS has an SSD mount option which changes some of the underlying logic. To date, I have not seen a compelling set of benchmark results to call it faster than without the mount option on an SSD.

    There are tools for BTRFS, including fsck. I do not know that I would call them stable (It's a relative term), nor do I believe that fsck is as essential as it was with the previous generation of filesystems.

    F
    Wasn't the btrfs fsck incompatible with the other ones (ext4 etc) ??

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    Quote Originally Posted by 89c51 View Post
    Wasn't the btrfs fsck incompatible with the other ones (ext4 etc) ??
    Yes. BTRFS and EXT4 are two different file system with completely different architectures, so this is expected.

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    Quote Originally Posted by russofris View Post
    Yes. BTRFS and EXT4 are two different file system with completely different architectures, so this is expected.

    F
    Yes of course thats true but i remember reading that it couldn't be used as the other ones hence you cant just fsck as with an ext4 for example.

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    between the COW and the online checking, there is less need for fsck on btrfs compared to ext3/4. The is a btrfsck since a few months ago:
    https://btrfs.wiki.kernel.org/index.php/Btrfsck
    and also
    https://btrfs.wiki.kernel.org/index.php/Restore
    If you do hit file system errors it is worth getting on the btrfs irc channel. they can help figure out if you have actually hit a bug in btrfs.

    @russofris
    for ext4 you could argue based on features. the main ones being less fragmentation, faster fsck, and more recently metadata checksums https://ext4.wiki.kernel.org/index.p...data_Checksums http://kernelnewbies.org/Linux_3.5#h...a7b417333147f8

    for btrfs you could argue that full checksumming makes the data much more safe. with traditional raid1 if a block differs between the 2 drives you only know that something is wrong (and you only notice when scrubbing), with brtfs 'raid1' you can see which version of the block has the right checksum and you can spot corruption without having to scrub.
    but the counter argument is that much newer code makes it very unsafe. i am sure some people wont consider btrfs safe until they know it has been in wide spread use for 5 years.

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    Quote Originally Posted by ssam View Post
    @russofris
    for ext4 you could argue based on features. the main ones being less fragmentation, faster fsck, and more recently metadata checksums
    Indeed. Unfortunately, I am still stuck with the perf/regression testing, and still have to write a CBA report for the directors. The other option is to wait for our vendor (RHEL or OEL) to adopt the new FS as a default/recommended option and implement it during the next cycle. To give you an example of what enterprise admins are up against, it took me almost 4 years and over 2 million dollars to migrate end-to-end from 1024 to 2048bit SSL. The meeting minutes from the project are available for your viewing.


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    I believe that fsck is as essential as it was with the previous generation of filesystems.

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    Quote Originally Posted by 89c51 View Post
    Wasn't the btrfs fsck incompatible with the other ones (ext4 etc) ??
    Despite users just calling "fsck" fsck is actually a wrapper that checks what filesystem you are running it against it, and then re-calls the appropriate fsck program --> fsck.ext4, fsck.xfs, fsck.resierfs etc. Every filesystem needs its own custom fsck (except maybe ext2 and 3 can use eachothers. but ext4 probably needs its own after all its new features), the only common link is the name and thats just for consistency.


    Ontopic: Im glad to see BTRFS maturing, and gaining speeds. its not as fast as ext4 but I definitely think that its usable in a desktop environment now without too much of a penalty, the only thing that bothers me is the possibility for large fragmentations and the fact that discard isnt enabled by default despite BTRFS detecting if its on an SSD automatically. I have an SSD so the fact discard isnt automatic is a bit of an annoyance, though admittedly fragmentation isnt as big of a deal to me since read's are all 1 universal speed unlike with traditional drives. I just always liked the fact that ext4 was good enough to not need a defragmentor most of the time.

    Side note: Why is Btrfs so good at threaded IO? Like what the f*ck? Thats a huge jump up from ext4 and xfs. Is it because of BTRFS design or what?

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