lkml.org 
[lkml]   [2006]   [Jan]   [22]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    From
    SubjectRe: soft update vs journaling?
    -----BEGIN PGP SIGNED MESSAGE-----
    Hash: SHA1



    Jan Engelhardt wrote:
    >>Unfortunately, journaling uses a chunk of space. Imagine a journal on a
    >>USB flash stick of 128M; a typical ReiserFS journal is 32 megabytes!
    >>Sure it could be done in 8 or 4 or so; or (in one of my file system
    >>designs) a static 16KiB block could reference dynamicly allocated
    >>journal space, allowing the system to sacrifice performance and shrink
    >>the journal when more space is needed. Either way, slow media like
    >>floppies will suffer, HARD; and flash devices will see a lot of
    >>write/erase all over the journal area, causing wear on that spot.
    >
    >
    > - Smallest reiserfs3 journal size is 513 blocks - some 2 megabytes,
    > which would be ok with me for a 128meg drive.
    > Most of the time you need vfat anyway for your flashstick to make
    > useful use of it on Windows.
    >
    > - reiser4's journal is even smaller than reiser3's with a new fresh
    > filesystem - same goes for jfs and xfs (below 1 megabyte IIRC)
    >

    Nice, but does not solve. . .

    > - I would not use a journalling filesystem at all on media that degrades
    > faster as harddisks (flash drives, CD-RWs/DVD-RWs/RAMs).
    > There are specially-crafted filesystems for that, mostly jffs and udf.
    >

    Yes. They'll degrade very, very fast. This is where Soft Update would
    have an advantage. Another issue here is we can't just slap a journal
    onto vfat, for all those flash devices that we want to share with Windows.

    > - You really need a hell of a power fluctuation to get a disk crippled.
    > Just powering off (and potentially on after a few milliseconds) did
    > (in my cases) just stop a disk write whereever it happened to be,
    > and that seemed easily correctable.

    Yeah, I never said you could cripple a disk with power problems. You
    COULD destroy a NAND in a flash device by nuking the thing with
    10000000000000 writes to the same area.

    >
    >
    > Jan Engelhardt

    - --
    All content of all messages exchanged herein are left in the
    Public Domain, unless otherwise explicitly stated.

    Creative brains are a valuable, limited resource. They shouldn't be
    wasted on re-inventing the wheel when there are so many fascinating
    new problems waiting out there.
    -- Eric Steven Raymond
    -----BEGIN PGP SIGNATURE-----
    Version: GnuPG v1.4.2 (GNU/Linux)
    Comment: Using GnuPG with Thunderbird - http://enigmail.mozdev.org

    iD8DBQFD09GOhDd4aOud5P8RAr1lAJ9fGMSJOd4QALc4nCbx+jDLgTlijwCbBM94
    r60oZO/x2Q0xEWeF9sp9Vz8=
    =63vo
    -----END PGP SIGNATURE-----
    -
    To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
    the body of a message to majordomo@vger.kernel.org
    More majordomo info at http://vger.kernel.org/majordomo-info.html
    Please read the FAQ at http://www.tux.org/lkml/

    \
     
     \ /
      Last update: 2006-01-22 19:43    [W:0.024 / U:1.160 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site