[OpenAFS] AFS cache

[Phil.Moore@morganstanley.com]

>>>>> "Alexei" == Alexei Kosut <akosut@stanford.edu> writes:
>>>>> "Derrick" == Derrick J Brashear <shadow@dementia.org> writes:

Alexei> I've also been wondering about this recently, albeit for a
Alexei> different (and less compelling) reason: I regularly transfer
Alexei> ten megabyte files via AFS using the Mac OS X Finder.  On my
Alexei> relatively slow ADSL connection, this can take nearly twenty
Alexei> minutes, but due to the AFS caching behavior, the Finder's
Alexei> progress dialog speeds through the entire file in just a few
Alexei> seconds, then "hangs" near the end until the file is actually
Alexei> copied to the AFS server, leaving me with no indication of how
Alexei> the transfer is actually proceeding.

Alexei> It would be nice if there was some way to make such progress
Alexei> meters more accurately reflect reality, especially if it could
Alexei> be done without compromising the efficiency gains from the AFS
Alexei> cache or by requiring changes to the Finder or other programs.

Derrick> Without fundamental changes to the cache manager I think it's
Derrick> hard to do without bypassing the cache entirely, in which
Derrick> case you write it out, then read it back over the
Derrick> network. Bleah.

I have the same reaction (except I've always spelled it "Blegh" for
some reason :-), however you *could* get what you want, IFF Apple were
to change the Finder's code in a very simple way.

If the Finder were to call fsync() every N bytes (I'd say every MB or
so), then you would get much more useful feedback from the progress
bars, as you would be effectively interleaving the cache and network
writes, from the viewpoint of the Finder.

I'd also say the chances of talking Apple into making this change are
pretty slim, but then, I've never asked Apple to do anything before,
so I'm just cynically assuming they are as stubborn as any commercial
vendor....