Chris Jones writes:
> 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.

As far as I understand it, presto doesn't just `cache NFS writes'. It
actually caches all synchronous writes to the local disk (which writes
from the NFS server daemon are, to comply with the NFSv2 spec).
Metadata writes happen to be synchronous too, so they get a speedup as
well.

I'm fairly certain that a certain site I used to work at (hi simonb! :)
even puts presto in their DECsystem 5000/260 ORACLE servers, because
that gets about 5% performance increase, and on those systems every %
counts (because there's no faster pmax boxen ;-)