Date: Wed, 20 Mar 2002 21:25:09 -0600 (CST) From: Quincey Koziol <koziol@ncsa.uiuc.edu> To: Dag-Erling Smorgrav <des@ofug.org>, freebsd-fs@freebsd.org Subject: Re: Filesystem books? Message-ID: <200203210325.g2L3P9P90443@sleipnir.ncsa.uiuc.edu> In-Reply-To: <xzp4rjc8i6r.fsf@flood.ping.uio.no>
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> Quincey Koziol <koziol@ncsa.uiuc.edu> writes:
> > > This basically looks like strongly typed filesystem - you could build
> > > this on top of any existing filesystem in FreeBSD using extended
> > > attributes and a userland library. Storing it in a single XML file is
> > > IMHO a regression, especially from a performance standpoint. Or did I
> > > miss some crucial point?
> > Sorta, the crucial part of the HDF5 library and file format is that the
> > files and library are designed to be portable between many different types
> > of machines,
>
> ...so you end up with something that sucks equally on all supported
> platforms. Sorry to sound so negative :)
Well, there are some challenges... ;-) Seriously though, our I/O speed is
typically 70-95% of the raw I/O speed on a system - we have spent significant
effort in optimizing our I/O path.
> I'm not sure if I got my point across, BTW - what I'm saying is that
> you can implement HDF (or equivalent functionality, anyway) as a
> userland library that will run on any system that offers POSIX
> filesystem semantics and (non-POSIX) extended attributes, instead of
> reinventing the wheel just to end up with something that will crawl
> like a crippled snail. It might not look as cool on your CV when
> you're done (not enough buzzwords) but it'd be a damn sight more
> useful. The biggest hurdle would be adapting the library to the
> different EA APIs out there.
Hmm, what set of the POSIX filesyetem semantics are you talking about?
Where is the best place to start looking into EA API stuff for FreeBSD?
> That being said, HDF makes a neat interchange format, once you get rid
> of the silly limitations on object size & count.
Hmm, which limitations are you talking about? I'm one of the main
library designers/developers for HDF5 (you are talking about HDF5 right, HDF4
does have a ridiculous number of limitations) and I'm always interested in
useful feedback about our design.
Thanks,
Quincey
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