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
next prev parent 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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