Large Files on IA32

Sean Dilda agrajag at
Fri Jul 27 06:32:06 PDT 2001

On Fri, 27 Jul 2001, Brian Macy wrote:

> We have been trying to get support for large files (>2GB) working on
> our PentiumIII cluster running under RedHat 6.2 with a 2.2.x
> kernel.  In particular, most of our parallel programs are MPI
> programs and use MPI-IO (ROMIO) to do parallel I/O.  I'm interested
> if other people have had success with such a set up, and whether
> they'd be interested in sharing experiences.

For LFS support, you will need a special kernel and a special glibc.
Any programs that you wish to use must have _FILE_OFFSET_BITS #define'ed
to be 64.  Anothe rcaveat is that you will probablly want to use lseek
instead of fseek and friends as fseek doesn't handle LFS.

If you wish to have a modified kernel and glibc, you can use the ones we
have on our ftp site.  They are based off of Red Hat Linux 6.2 and as
far as I know should work on a normal Red Hat 6.2 system, although I've
never tried it.  Another option is to just use Scyld Beowulf as LFS
support is included and a few key apps are recompiled in order to work
with LFS.

As for ROMIO, I'm not sure wether having the underlying OS support files
over 2G is enough for ROMIO to work with them.
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