I am having issues with read performance on our cluster using NFS ( and also SMB) . Any initial file transfer to the clients seems to be limited to ~40MB/s. This is not a limitation of the underlying array, as I can read the same file on the server at ~160MB/s. Similarly, after the file has been read into memory on the server, the clients can read it at ~100MB/s (this is following a NFS umount and mount on the client). The clients can write to the server at ~90MB/s.
All of this leads me to believe the issue I am experiencing is not directly network or disk related, but rather a factor of the network latency combined with disk request latency, such that the client is not sending enough read requests (fast enough) to keep the server disk busy. I looked into a method to have the client or server NFS perform a read ahead such that it would keep the disk busy and alleviate the latency performance hit I suggest above. Perhaps someone can offer a solution or point me in a different direction as the above may not really be the issue. I have tried adjusting a number of kernel parameters to increase the TCP window size but it has not had any affect. Thanks, Glen I've left out a lot of detail to keep this succinct. I can provide it when necessary. _______________________________________________ Beowulf mailing list, [email protected] To change your subscription (digest mode or unsubscribe) visit http://www.beowulf.org/mailman/listinfo/beowulf
