[Beowulf] MPI and Redhat9 NFS slow down
joachim at ccrl-nece.de
Tue Aug 24 00:34:39 PDT 2004
Jack Chen wrote:
> I have tried to mount the drive using different parameters (rw,soft
> and rw,hard,bg,intr,noac) and increased the nfsd daemon from 8 to 16
> on the NSF server, but nothing change.
MPI-IO (are you doing this?) via NFS is generally not for large amounts
of I/O. Two things:
- you need to mount with the noac option to ensure a certain degree of
consistency between nodes
- increasing the NFS block size to 8kB can increase performance.
> If you have any idea on what is going on, please help!
First, you should determine the I/O performance that can be achieved for
the different NFS mounted directories with a tool like bonnie and see
what magnitude of performance you can expect. Than you need to see what
the application is actually doing for I/O.
And check the ethernet configuration - it might also be a full/half
duplex problem between those nodes.
You also might consider using a more appropiate (parallel) file system
Joachim Worringen - NEC C&C research lab St.Augustin
fon +49-2241-9252.20 - fax .99 - http://www.ccrl-nece.de
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