From: Norbert Paschedag (noe_at_physik.unizh.ch)
Date: Thu Dec 06 2007 - 13:21:45 CET
Date: Thu, 6 Dec 2007 13:21:45 +0100 (CET) From: Norbert Paschedag <noe@physik.unizh.ch> Message-ID: <Pine.LNX.4.64.0712061321110.6336@hesse.math.tu-berlin.de> Subject: Re: [suse-sles-e] Very high MD latencies with SLES10 SP1.
On Thu, 6 Dec 2007, Dr J Pelan wrote:
>
> On Wed, 5 Dec 2007, Norbert Paschedag wrote:
>
> > The sd devices alone show normal timings, it seems the MD device that's
> > causing these latencies. Any idea which parameter to change here ? Any
> > caveats regarding MD RAID1 that I missed ?
>
> I suspect you are correct. I can't make any claims without hard numbers
> but I certainly sense that there has been a drop in the 'responsiveness'
> of the system during md disk activity. I first thought this was due to a
> driver issue but I have seen this on a couple of different machines.
> I did switch to the deadline IO scheduler which may have helped.
I tried that already and it did help only marginally.
I also tried various other I/O-related settings, without success so far.
Norbert
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