NFS file server performance

[Jag]

On Mon, 26 Mar 2001, Art Edwards wrote:

> I'm new to Beowulf. I have just gotten a small athalon cluster running
> under Scyld and I was interested in your comments about file transfer.
> I am under the impression that an MPI data transfer does not use NFS. Is 
> this true? Also, Given the bus speed of normal motherboards, does 
> increasing the network speed have a large impact on global performance?

MPI does not use nfs.  nfs is used when you're on a slave node and try
to look at a file in /home.  It uses nfs to make that file (which is
really on the head node) available to the slave node.

The performance increase from increasing network speed depends on what
you are doing.  If your jobs are sending a lot of data over the network
and are having to sit idle while it waits for data to be transfered,
then yes, increasing network speed will improve overal performance.  If
that's not the case, then increasing network speed will probablly speed
up the startup of your programs a little as well as boottime for the
slave nodes, but won't really affect much other than that.


Jag
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