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Fedora Logical Volume Manager Benchmarks

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  • phoronix
    started a topic Fedora Logical Volume Manager Benchmarks

    Fedora Logical Volume Manager Benchmarks

    Phoronix: Fedora Logical Volume Manager Benchmarks

    Last month when publishing Fedora 15 vs. Ubuntu 11.04 benchmarks in some of the disk workloads the Fedora Linux release was behind that of Ubuntu Natty Narwhal. Some users speculated in our forums that SELinux was to blame, but later tests show SELinux does not cause a huge performance impact. With Security Enhanced Linux not to blame, some wondered if Fedora's use of LVM, the Logical Volume Manager, by default was the cause.

    http://www.phoronix.com/vr.php?view=16190

  • mercutio
    replied
    Originally posted by Kari18
    not using barriers = I don't care about data = fedora is unfit for every even slightly serious setup.
    I don't think fedora has ever meant to have been for serious setups. It's more a distribution to try things out, before putting into RHEL.

    Leave a comment:


  • Zapitron
    replied
    Another weird LVM speedup

    I stumbled upon another weird case where someone saw LVM be faster than directly using partitions. Turned out the LVM overhead (or maybe just the tester's whims) made a 1TB disk become slightly less than 1TB and apparently that allowed XFS (without inode64 mount option) keep inodes closer to their data. Life can be full of surprises.

    Michael's tests were with ext4, though. And it's more of a size thing than an LVM thing, but if using LVM changes your sizing habits, then some performance differences could seem LVM-related...

    Leave a comment:


  • liam
    replied
    Originally posted by energyman View Post
    >EXT4-fs (dm-1): mounted filesystem with ordered data mode

    is the mount message from ext4. Filesystem, underlying device, mount options.

    Nothing from lvm.
    That's my point: the message should be from LVM since it is doing the management of said device.
    Per this message, https://bugzilla.kernel.org/show_bug.cgi?id=9554#c0, syslog should report if barrier's are enabled but not supported by lvm.
    I don't see the message, q.e.d., error not ocuring.
    Do you have any link to documentation, or command I can run, that would say otherwise?

    Leave a comment:


  • energyman
    replied
    >EXT4-fs (dm-1): mounted filesystem with ordered data mode

    is the mount message from ext4. Filesystem, underlying device, mount options.

    Nothing from lvm.

    Leave a comment:


  • liam
    replied
    Originally posted by energyman View Post
    you are looking at the wrong stuff. Even if ext4 tries to use barriers if lvm does not support them you are SOL.



    which will do nothing, if lvm does not support barriers.
    Unless I'm mistaken that WAS the lvm message (EXT4-fs) since lvm is the one who would be responsible for the device management (hence dm).
    If you can find some documentation that shows otherwise and where I should look I would appreciate it.

    Leave a comment:


  • energyman
    replied
    Originally posted by liam View Post
    I don't care what the article said, I'm telling you what the fedora site said. I trust the guys who wrote this stuff more than Michael, in this case, especially since I haven't been able to find any evidence that fedora disables barriers at any level.
    For the record, this F15 laptop says
    Code:
    EXT4-fs (dm-1): mounted filesystem with ordered data mode
    you are looking at the wrong stuff. Even if ext4 tries to use barriers if lvm does not support them you are SOL.

    Originally posted by gilboa View Post
    Does anyone has any type of official link stating that Fedora 15 indeed doesn't support write barriers on ext4 over LVM?
    (I have no problems remounting ext4 with mount / -o remount,barrier; by default ext4 is mounted in ordered mode)

    - Gilboa
    which will do nothing, if lvm does not support barriers.

    Leave a comment:


  • gilboa
    replied
    Does anyone has any type of official link stating that Fedora 15 indeed doesn't support write barriers on ext4 over LVM?
    (I have no problems remounting ext4 with mount / -o remount,barrier; by default ext4 is mounted in ordered mode)

    - Gilboa
    Last edited by gilboa; 07-04-2011, 03:19 AM.

    Leave a comment:


  • liam
    replied
    Originally posted by chithanh View Post
    I wonder why the article then claims thatA check of dmesg should decide the matter.
    I don't care what the article said, I'm telling you what the fedora site said. I trust the guys who wrote this stuff more than Michael, in this case, especially since I haven't been able to find any evidence that fedora disables barriers at any level.
    For the record, this F15 laptop says
    Code:
    EXT4-fs (dm-1): mounted filesystem with ordered data mode

    Leave a comment:


  • yesterday
    replied
    What a typical phoronix thread. An unsubstaniated comment about a distribution accepted as fact to fuel nerdrage

    Leave a comment:

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