-----Original Message-----
From: linux-raid-owner@vger.kernel.org [mailto:linux-raid-
owner@vger.kernel.org] On Behalf Of Justin Piszcz
Sent: Monday, December 22, 2008 7:59 AM
To: linux-raid@vger.kernel.org
Cc: smartmontools-support@lists.sourceforge.net
Subject: Spread Spectrum (SSC) Enable or Disable?

Besides the power supply/surge/etc with a lot of drives-- I have read:

http://www.wrightthisway.com/Articles/cat_reviews.html
"As I mentioned earlier, the enclosure will definitely handle drives
using Spread Spectrum Clocking (SSC), an increasingly common feature
that helps reduce electromagnetic interference, especially between
drives in close proximity with each others, such as you might have in

a

RAID setup, so that is a definite plus here."

With 16-24 disks-- if they are close together, it sounds like a good
idea to use Spread Spectrum Clocking?
Does anyone here with a large-ish raid array use this?

Any enterprise-insiders care to comment?

Justin.
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I know for a fact that Xyratex supports SSC on SOME of their enclosures.
However,
there is a caveat to be aware of ... some RAID
controllers/firmware/enclosure combinations
have problems "seeing" disks that have SSC enabled.  Don't just turn
this on unless you
verify with the enclosure manufacturer that they support SSC for your
desired combination.

David