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From: Mirko Benz <mirko.benz@web.de>
To: "Moore, Eric" <Eric.Moore@lsil.com>
Cc: linux-scsi@vger.kernel.org
Subject: Re: SATA on mptsas performance
Date: Wed, 15 Feb 2006 08:52:07 +0100	[thread overview]
Message-ID: <43F2DDA7.7050700@web.de> (raw)
In-Reply-To: <F331B95B72AFFB4B87467BE1C8E9CF5F28A5FF@NAMAIL2.ad.lsil.com>

Hello,

The SAS3442X is connected to the JBOD via a x4 SAS cable.
The JBOD has an LSI SAS Expander chip - no port multiplier.
Disks are Seagate ST3300831AS (300 GB, SATA-I, NCQ)

Does the SAS controller and the SAS expander communicate at 3 Gb when 
accessing SATA disks?
If not it should give 4 * 150 MB/s r/w throughput for this configuration.

I am testing with parallel dd invocations on the raw device e.g.:
dd if=/dev/sdb of=/dev/null bs=32k count=10000 &
...
dd if=/dev/sdl of=/dev/null bs=32k count=10000 &

I have tested with IOMETER but the results are worse.

I will test SATA II disks later. But I assume there is a scheduling 
problem (mapping 10 disks to 4 channels). The CPU load is also very high.

Disks support NCQ but it should have no effect due to sequential access 
of a single application per disk. How to switch on/off NCQ?

Regards,
Mirko


  reply	other threads:[~2006-02-15  7:52 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2006-02-14 16:02 SATA on mptsas performance Moore, Eric
2006-02-15  7:52 ` Mirko Benz [this message]
2006-03-01  3:30   ` Douglas Gilbert
2006-03-01  6:09     ` Jeff Garzik
2006-03-01  8:16       ` Mirko Benz
2006-03-01 17:55     ` Asgeir Eiriksson
  -- strict thread matches above, loose matches on Subject: below --
2006-03-01 16:04 Moore, Eric
2006-02-13 14:01 Mirko Benz

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