On Fri, 5 Dec 1997 14:09:33 -0600 (CST) 
 Ty Sarna <tsarna@endicor.com> wrote:

 > hsmfs should also implement the O_NONBLOCK flag. Opening a nonresident
 > file with O_NONBLOCK should return EWOULDBLOCK and start bringing the
 > file in. That way, a program that knows it's going to need data in a
 > bit, but needs to do some calculations first, can start getting the file
 > ready, and parallelize things a bit.

The way NAStore currently works is that blocking is only required if
you read past the portion of the file that has already been restored.

I.e. opening triggers the file restoration, and if 100 bytes have been
restored, and you only want to read the first 10, you can do that.

These "rapid-access" semantics haven't, to my knowledge, caused any
real problems on the Convex systems on which NAStore currently runs.

Jason R. Thorpe                                       thorpej@nas.nasa.gov
NASA Ames Research Center                            Home: +1 408 866 1912
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