[Beowulf] network filesystem

Robert Latham robl at mcs.anl.gov
Tue Mar 6 08:06:54 PST 2007

On Tue, Mar 06, 2007 at 08:17:32AM +0900, Stu Midgley wrote:
> I can't think of any benchmark you care to mention that a single
> lustre OSS/MDS won't outperform NFS.  

Consider an MPI-IO benchmark where all processes write to different
regions of a file.  This workload is common in scientific
applications, say when all processes need to write an HDF5 element to
a datafile.

Run that benchmark with one processor and you will get great
performance out of Lustre.  Lustre does an excellent job of caching
data amd making single-processor I/O go really really fast.

Run that benchmark with two processors, and the clients will spend a
great deal of time revoking each others extent-based locks and
expiring entries from their caches.  Performance will take a
significant hit, but will increase as you add more processes.

I don't mean to come across as a Lustre hater.  I'm just trying to
keep the discussion honest:  the discussion of the "right" file system
for an application is hard, and lots of factors come into play.


Rob Latham
Mathematics and Computer Science Division    A215 0178 EA2D B059 8CDF
Argonne National Lab, IL USA                 B29D F333 664A 4280 315B

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