Date: Fri, 22 Sep 2000 23:42:13 -0600 From: Wes Peters <wes@softweyr.com> To: Warner Losh <imp@village.org> Cc: Douglas Swarin <doug@staff.texas.net>, freebsd-hackers@FreeBSD.ORG, kkemp@nwcr.net Subject: Re: Frustration with SCSI system Message-ID: <39CC42B5.42FB21FD@softweyr.com> References: <20000921182405.A82919@staff.texas.net> <20000920125128.F9141@fw.wintelcom.net> <NOEDICFPJKLKIDADMFFNKEIFDAAA.kkemp@nwcr.net> <200009212344.RAA63251@harmony.village.org>
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Warner Losh wrote:
>
> In message <20000921182405.A82919@staff.texas.net> Douglas Swarin writes:
> : Ideally, I would use one of the IDE flash-based drives on the market. One
> : brand is SanDisk, and they take a standard IDE connector and fit into a
> : 3.5" drive bay. You can get them very reasonably priced up to 128MB or
> : so, which is just fine for a boot partition. Since flash drives have no
> : moving parts, mechanical failure is not an issue, and since the root
> : partition is not written to much, the flash will not wear out for a
> : long time (flash cells wear out after about 100,000 writes; the flash
> : drives do load balancing and stuff to ensure that the (many) cells in
> : the drive are written to evenly).
>
> We use these devices heavily at Timing Solutions. Or rather we use
> a IDE <-> CF adapter and haven't had any devices wear out. And some
> of these devices have had rather heavy use. I think that it is closer
> to 1 million writes per cell, but I don't have my spec sheets handy.
The newer devices do 1 million writes per cell. When I left Xylan earlier
this year, some of our early (late '94 or early '95) flash devices were
just beginning to fail. These were development machines that saw a lot
of write cycles, and their home-grown flash filesystem does a pessimal
job of rewriting the same cells over and over again.
> Are you sure that they do write balancing? The indications I have
> from the base chip technology is that they don't. I could have missed
> that in the data sheets. It has been a little while since I looked at
> them, so I might be misremembering. I can't seem to find the data
> sheets I looked at before.
SanDisk does, in the controller chip. Good technology.
--
"Where am I, and what am I doing in this handbasket?"
Wes Peters Softweyr LLC
wes@softweyr.com http://softweyr.com/
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