First of all, good luck, I think you'll need it.

Not sure on sRAM but I don't think any moving parts based hard disk is gonna
cut it. For one there's the 100G the other thing is that PC hard disks (the
more shock resistant laptop drives may be better) don't like running when
they're not level (or at least used too). I'm not sure how sensitive the
latest drives are (of course you won't find a recent drive <2Gb) but not
long ago as little as 5 degrees of slope could screw an IDE drive.

Unless 100G is a misprint I think about the only option is solid state.
Sandisk (www.sandisk.com) make a few solid state mini storage products.

They have solid state hard drives ranging from 32Mb-440Mb in 2.5" form
factor. They also have compact flash cards the size of a matchbook in from
4-96Mb. Both are PCMCIA and ATA compliant and

However they are probably not suitable due to the following:
1) Rewrites
        Both products list data reliability as < 1 non-recoverable error in
10 to the 14 bits read. On a 160Mb drive this would allow approx. 77000
rewrites before a single bit failure is expected. Along with this is the
problem of bad blocks however I believe they have implemented some sort of
hardware bad block table (can't really remeber, check the specs, in any case
I've seen info on dealing with the bad blocks and it didn't look too
hideously hard. Also, I think this was mainly to do with bad blocks present
at manufacturing).

2) Vibration
        You mention the product will see 100+G of shock and vibration. This
could be a big problem. Keep in mind these are both completely solid state
so unless there poorly manufactured they *should* be typical of other solid
state devices. In terms of shock, you're fine. They are rated for 2000G max.
of shock while operating (exactly the same if not operating suprise
surprise). However they are only rated at 15G peak to peak max. vibration
and so you may have problems here. Granted this could be due to their
manufacturing. But If a solid state flash drive can only take 15G then I
can't see why a solid state SRAM will take significantly more.

----- Original Message -----
From: William K. Borsum <borsum@DASCOR.COM>
Subject: IDE or Memory Card use for high speed data storage
> Greetings:
> I've been following the PIC to FDC conversations a bit, and have a related
> question:
>
> I have an application where I need to log data at the rate of up to 200
> K-bytes per second, to a depth of 120-160 Mega-bytes.
> Part of the problem is that it is memory is broken up into a series of
ring
> buffers that are sequentially  over-written till an event occurs, so flash
> or eeProm with a short finite life--or holes in the memory because of bad
> blocks--won't work.
<SNIP>
>Oh yes--environment sees shock and vibration to
> 100+ G's, and the whole thing needs to fit in a can about 3.5" in
diameter.
<SNIP>
>William K. Borsum, P.E.
>OEM Dataloggers and Instrumentation Systems
><borsum@dascor.com> & <www.dascor.com>