On Fri, Jul 04, 2008 at 08:41:26AM +0200, Jens Beyer wrote:
>
> Hi,
>
> I have encountered a strange performance problem during some
> hardware evaluation tests:
>
> I am running a benchmark to measure especially random read/write
> I/O on an raid device and found that (under some circumstances)
> the performance of Random Read I/O is inverse proportional to the
> size of the tested XFS filesystem.
>
> In numbers this means that on a 100GB partition I get a throughput
> of ~25 MB/s and on the same hardware at 1TB FS size only 18 MB/s
> (and at 2+ TB like 14 MB/s) (absolute values depend on options,
> kernel version and are for random read i/o at 8k test block size).
Of course - as the filesystem size grows, so does the amount of
each disk in use so the average seek distance increases and hence
read I/Os take longer.
Cheers,
Dave.
--
Dave Chinner
dchinner@xxxxxxxxx
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