Proposal for a new I/O library design
Alastair Reid
alastair@reid-consulting-uk.ltd.uk
Tue, 29 Jul 2003 01:20:41 +0100
> If it's not possible to provide a guarantee of File identity then we
> should probably drop the whole idea of File values.
I haven't been following in enough detail to know if File values are a good
idea or not but it's maybe worth mentioning that if you're NFS, there's no
way to test file identity. IIRC, the problem is that a machine might
nfs-export overlapping parts of its filesystem so you might have two names
for the same file.
--
Alastair Reif
ps (At least in FreeBSD) mmapping an NFS-mounted file can also lead to
unhappiness. If you mmap the same NFS-mounted file multiple times, you can
end up with multiple copies of the same page which leads to chaos when you
start writing to the pages. (At least, that was the conclusion we came to
when trying to understand why libelf produced incorrect results when used
with NFS-mounted files if compiled with mmapping turned on but produced
correct results for NFS-mounted files with mmapping turned off and with local
files (mmapping on or off).