>>>>> "David" == David Maxwell <david@fundy.ca> writes:

David> This isn't a direct reply, but along these lines, has anyone
David> ever seen a non-volatile RAM PCI card that a driver could
David> create a buffer in to survive system restarts? Seems like a
David> simple enough idea that there would be one out there already...

Yeah, there are, of course, the old prestoserve cards.  I found one in
an old pmax I had, and I lent it to Michael Hitch to experiment with.
At the time, I think it was discussed a little bit, either here or on
port-pmax.

As I understand it (which understanding may be orthogonal to reality),
the prestoserve card was originally used to cache NFS writes.  One of
the ideas thrown around in the discussion I mentioned, though, was
caching all metadata, in addition to NFS writes, on the card.  The
could theoretically give you some really spiffy filesystem
performance.

The presto card I found was a normal DECStation memory module, with a
battery on it.  You put it in the last slot, preferably separated from
other memory by at least one blank slot, and the memory mapping magic
somehow figures out that it's there and not to be used as a normal
memory module.  Or something.

Chris

-- 
-----------------------------------------------------cjones@math.montana.edu
Chris Jones                                          cjones@honors.montana.edu
           Mad scientist at large                    cjones@nervana.montana.edu
"Is this going to be a stand-up programming session, sir, or another bug hunt?"