From: Hannes Dorbath <light@theendofthetunnel.de>
To: Justin Piszcz <jpiszcz@lucidpixels.com>
Cc: Gabor Gombas <gombasg@sztaki.hu>,
linux-ide-arrays@lists.math.uh.edu, xfs@oss.sgi.com,
linux-raid@vger.kernel.org, linux@vger.kernel.org
Subject: Re: Software RAID5 Horrible Write Speed On 3ware Controller!!
Date: Wed, 18 Jul 2007 13:26:11 +0200 [thread overview]
Message-ID: <469DF8D3.8020908@theendofthetunnel.de> (raw)
In-Reply-To: <Pine.LNX.4.64.0707180718000.7659@p34.internal.lan>
On 18.07.2007 13:19, Justin Piszcz wrote:
> For the HW RAID tests (2) at the bottom of the e-mail, no, I did not set
> nr_requests or use the deadline scheduler.
>
> For the SW RAID tests, I applied similar optimizations, I am probably
> not at the latest firmware. The main thing I wanted to use though was
> SW RAID because the card itself offers so many ports, however, with
> write speed being that slow I am not sure its a good idea.
I think what you might be experiencing is that XFS can read su,sw values
from the MD device and will automatically optimize itself, while it
can't do that for the HW RAID device. It is absolutely essential to
align your file system, to prevent implicit reads, needed for parity
calculations.
Set su to the stripe size you have configured in your controller (like
128K) and sw to 9 (for a 10 disk RAID 5 array).
--
Regards,
Hannes Dorbath
next prev parent reply other threads:[~2007-07-18 11:26 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-07-18 10:23 Software RAID5 Horrible Write Speed On 3ware Controller!! Justin Piszcz
2007-07-18 10:49 ` Hannes Dorbath
2007-07-18 16:26 ` Justin Piszcz
2007-07-18 17:18 ` Bryan J. Smith
2007-07-18 10:59 ` Al Boldi
2007-07-18 12:01 ` Justin Piszcz
2007-07-18 11:05 ` Gabor Gombas
2007-07-18 11:19 ` Justin Piszcz
2007-07-18 11:26 ` Hannes Dorbath [this message]
2007-07-18 11:32 ` Justin Piszcz
2007-07-18 11:37 ` Hannes Dorbath
2007-07-18 11:38 ` Justin Piszcz
2007-07-18 12:51 ` Robin Hill
2007-07-18 14:26 ` Gabor Gombas
2007-07-18 11:17 ` Giuseppe Ghibò
2007-07-18 11:20 ` Justin Piszcz
2007-07-18 17:57 ` Bryan J. Smith
2007-07-18 11:26 ` Sander
2007-07-18 11:35 ` Justin Piszcz
2007-07-18 12:09 ` Sander
2007-07-18 12:19 ` Justin Piszcz
2007-07-18 13:32 ` Sander
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