Re: hard disk performance on Allnet 6500 (like Thecus N2100)
On Mon, Sep 24, 2007 at 07:54:37PM +0200, Martin Michlmayr wrote:
> * Oliver Kiddle <okiddle@yahoo.co.uk> [2007-07-11 11:27]:
> > After installing Debian, I've found that the disc speed as reported by
> > hdparm has gone down. Before, I was getting:
> ...
> > Whereas now I get:
> > Timing cached reads: 60 MB in 2.00 seconds = 29.95 MB/sec
> > Timing buffered disk reads: 60 MB in 3.07 seconds = 19.53 MB/sec
>
> Apologies for not answering your message back in July. Paul Fryer
> recently made me aware of that problem again and I looked at it today.
> First of all, I see about the same peformance as you do. Second, I
> tried two tests with 2.6.22 to see what might make a difference but I
> couldn't increase the performance:
>
> - First, I reverted that R_ERR on DMA activate FIS errata fix which
> you noticed in dmesg. Reverting this fix does not increase
> performance.
>
> - Second, I applied Intel's IOP patches from SourceForge but again
> they didn't help.
>
> So I'm not quite sure why Debian with a modern kernel is much slower
> to whatever Thecus' firmware was using. If anyone else has any good
> ideas I'd love to hear them.
I believe a bug was found at some point in hdparm that caused it to
generate incorrect test values (of by a factor of 2 as far as I
remember). This would cause comparing the results between old (broken)
and new (fixed) versions of hdparm to look as if things had suddenly
gotten much worse.
Maybe that is what is the case here.
--
Len Sorensen
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