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    SubjectRe: fsync on large files
    "Stephen C. Tweedie" wrote:
    > Linus, this makes very little sense right now: there is an _urgent_
    > need for a journaled filesystem for Linux, and there is an urgent need
    > for a solution which is of production quality. Implementing a new
    > filesystem from scratch is hardly the way to achieve that. The
    > recovery time of ext2 on large filesystems is a real showstopper to
    > many potential applications.

    As someone trying to actually deploy 80+ GB
    RAIDed database servers right now on Linux, I can
    certainly second Stephen's opinion. About the
    *only* problem with ext2 right now is the
    long fsck times. I've attached some measurements
    to show you how serious the problem is.


    ---- from posting to linux-raid

    $ df
    Filesystem 1024-blocks Used Available Capacity Mounted on
    /dev/hda2 7802206 1127480 6270290 15% /
    /dev/md0 85570400 56 81152504 0% /mnt/raid

    # time mount /dev/md0 /mnt/raid
    0.00user 0.25system 0:10.99elapsed 2%CPU (0avgtext+0avgdata
    0inputs+0outputs (94major+12minor)pagefaults 0swaps

    [ That's 11 seconds ]

    To measure fsck performance, since it took about 2 hours
    to actually *fill* the drive to 11% full, I had to resort
    to extrapolation. Here are my hard results.

    % Disk full Data blocks Time
    5% 3881184 5m35s (335s)
    7% 6015252 7m33s (453s)
    11% 8961576 9m59s (599s)

    The data consisted of numerous copies of /usr/doc from
    RedHat, therefore it's a fairly representative mix of
    small files.

    Extrapolating using an *extremely dodgy* linear
    approximation gives the following estimates:

    50% 40m (2400s)
    90% 66m40s (4000s)


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