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Subject: Swap on flash SSDs
From: Dave Hansen <dave@linux.vnet.ibm.com>
In-Reply-To: <4B2BD55A.10404@sgi.com>
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Date: Fri, 18 Dec 2009 11:28:07 -0800
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To: Mike Travis <travis@sgi.com>
Cc: Christoph Lameter <cl@linux-foundation.org>, Ingo Molnar <mingo@elte.hu>, Rik van Riel <riel@redhat.com>, Andrea Arcangeli <aarcange@redhat.com>, linux-mm@kvack.org, Marcelo Tosatti <mtosatti@redhat.com>, Adam Litke <agl@us.ibm.com>, Avi Kivity <avi@redhat.com>, Izik Eidus <ieidus@redhat.com>, Hugh Dickins <hugh.dickins@tiscali.co.uk>, Nick Piggin <npiggin@suse.de>, Mel Gorman <mel@csn.ul.ie>, Andi Kleen <andi@firstfloor.org>, Benjamin Herrenschmidt <benh@kernel.crashing.org>, KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>, Chris Wright <chrisw@sous-sol.org>, Andrew Morton <akpm@linux-foundation.org>, "Stephen C. Tweedie" <sct@redhat.com>
List-ID: <linux-mm.kvack.org>

On Fri, 2009-12-18 at 11:17 -0800, Mike Travis wrote:
> Interesting discussion about SSD's.  I was under the impression that with
> the finite number of write cycles to an SSD, that unnecessary writes were
> to be avoided?

I'm no expert, but my impression was that this was a problem with other
devices and with "bare" flash, and mostly when writing to the same place
over and over.

Modern, well-made flash SSDs and other flash devices have wear-leveling
built in so that they wear all of the flash cells evenly.  There's still
a discrete number of writes that they can handle over their life, but it
should be high enough that you don't notice.

http://en.wikipedia.org/wiki/Solid-state_drive

-- Dave

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