Date: Fri, 19 May 2006 10:35:10 -0700 From: "marty fouts" <mf.danger@gmail.com> To: "Jim Thompson" <jim@netgate.com> Cc: gnn@freebsd.org, freebsd-small@freebsd.org Subject: Re: Flash File Systems or Translation Layers? Message-ID: <9f7850090605191035n746eec0etb2546dd5e15e5ccf@mail.gmail.com> In-Reply-To: <EC0C34CD-EE21-4FCA-ACEE-23B63EEFA9DE@netgate.com> References: <m2bqtwoena.wl%gnn@neville-neil.com> <446BBE65.50104@FreeBSD.org> <9f7850090605171746p5ff4dbefq46211ce93aafc116@mail.gmail.com> <446C2380.6020000@FreeBSD.org> <A2451718-0B8F-4BF2-9466-F6EDC6DC212B@netgate.com> <9f7850090605181006m56c38a56lcc7037beaf6b6fa@mail.gmail.com> <2159F853-C89E-4032-9931-56F4B7D214C0@netgate.com> <9f7850090605181118o30b71b94mca294b2195e9ae1e@mail.gmail.com> <EC0C34CD-EE21-4FCA-ACEE-23B63EEFA9DE@netgate.com>
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On 5/18/06, Jim Thompson <jim@netgate.com> wrote: > Your >=3D 64MB requirement also tends to 'signal' why you prefer NAND > flash, as its much less > expensive than NOR flash in similar densities. Still, this "64MB" > requirement makes for an expensive board. TS7250, quantity 1, with 128mb NAND is < $200 US. That's hardly expensive. It's one of the cheapest ARM based development board that I'm aware of. > > Agreed. But I think that NAND and NOR are enough different that they > > need to be supported differently. > > Perhaps, thought I will allow that JFFS2 can deal with both, and a > good FTL would be able to 'hide' most of > the details. Here we have to agree to disagree. My experience with JFFS2 suggests that while it can "deal" with NAND, it doesn't do so very well. I also don't believe that a single FTL works well to cover the range of differences between NOR and NAND. I'd rather have a separate FTL for each, that concentrates on doing a good job for that kind of flash.
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