[DRBD-user] sync rate only 2,204 (1,220) K/sec?

Peter Sabaini peter at sabaini.at
Thu Oct 5 10:42:10 CEST 2006


On Wednesday 04 October 2006 19:30, Lars Ellenberg wrote:
> / 2006-10-04 18:36:40 +0200
>
> \ Peter Sabaini:
> > > > # hdparm -t /dev/cciss/c0d0
> > > >
> > > > /dev/cciss/c0d0:
> > > >  Timing buffered disk reads:  208 MB in  3.03 seconds =  68.69 MB/sec
> > > >
> > > > It could be better, but its reasonable I think?
>
> well, actually, write performance would be more interesting.
> make sure that the raid is not rebuilding at the same time.
>
> also, the cciss controler likes high values for
>  max-buffers
>  max-epoch-size
>  unplug-watermark

Ok, that helped -- I now get around 23MB/s which is not great but a lot better 
than before :-)

For the record I now use

    sndbuf-size         1M;
    max-buffers      32768;
    max-epoch-size   16384;
    unplug-watermark 32768;

I cant test right now but from an earlier naive test (dd if=/dev/zero 
of=zero.dat bs=1M count=4096) write performance was around 32MB/s for the 
disk device (ext3 on top of lvm), so thats the limiting factor now I guess. 
Any advice on getting more out of that cciss? :-)

Thanks a lot,
peter.


-- 
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 Peter Sabaini
 ARC Seibersdorf research GmbH
 Biomedical Engineering / eHealth systems
 Reininghausstrasse 13/1, 8020 Graz, Austria
 T: +43(0)316 586570-55, F:+43(0)316 586570-12
 peter.sabaini at arcsmed.at, http://www.arcsmed.at/ehs



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