Message-ID: <442037D2.7060109@comcast.net>
Date: Tue, 21 Mar 2006 12:28:50 -0500
From: John Richard Moser <nigelenki@comcast.net>
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To: David Vrabel <dvrabel@cantab.net>
CC: linux-kernel@vger.kernel.org
Subject: Re: Lifetime of flash memory
References: <44203179.3090606@comcast.net> <44203468.9060806@cantab.net>
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David Vrabel wrote:
> John Richard Moser wrote:
>> The question I have is, is this really significant?  I have heard quoted
>> that flash memory typically handles something like 3x10^18 writes;
> 
> That's like, uh, 13 orders of magnitudes out...
> 

Yeah I did more searching, it looks like that was a mass overstatement.
 There was one company that did claim to have developed flash memory
with that size (I think it was 3.8x10^18) but it looks like typical
drives are 1.0x10^6 with an on-chip wear-leveling algorithm.  Assuming
the drive is like 256 megs with 64k blocks, that's still 129 years at
one write per second.

Bigger drives of course level over larger area and lifetime increases
linearly.  My 512M drive should last 260 years in that scheme; a 4 gig
iPod Nano would last 2080 years; and a 30GiB flash-based hard disk in a
Samsung laptop on a single control chip doing the wear leveling over
multiple NAND chips would last 15600 years.

In theory anyway.  And assuming one write on one block per one second on
average for the duration.  (obviously the iPod nano sustains many times
less than that and will last hundreds of thousands of years in normal
usage).


> David Vrabel
> 

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