UNCLASSIFIED Hi all,
Coming in late to this conversation... It seems to me, that data going in to the workstation is ok, to local disk, but data going out, to a NFS share is the slow part. Have you considered adding another NIC to the workstation, and making that new one dedicated to receiving the data, and the primary one, dedicated to deliverying the data to the NFS server, as well as everything else network related. This would eliminate potential contention issues on the wire, and clearly point the finger to where the issue lies. Others have suggested good points for the NFS server to consider... Greg. -----Original Message----- From: tech-boun...@lopsa.org [mailto:tech-boun...@lopsa.org] On Behalf Of Patrick Cable Sent: Friday, 24 September 2010 11:18 AM To: tech@lopsa.org Subject: [lopsa-tech] The FPGA and the NFS mount: A tale of bursty writes I have a device that sends out information at 4.7 Megabytes a second. I have a desktop that receives the data from this device that runs Red Hat Enterprise Linux 5.5. They are on the same switch, a 24-port Juniper EX2200. When I write the data to the desktop on the local filesystem, there's no dropped information. When I write the data to an NFS share, the device reports dropped packets. I have tried playing with the rsize/wsize NFS parameters (8192K seems to be the best value), and values in /proc/sys/net/core/{r,w}mem_{default,max} and increasing the NFS daemon count, as suggested by http://nfs.sourceforge.net/nfs-howto/ar01s05.html. Very similar results across the board. The NFS server also runs RHEL5.5. It's got 11 600gb 15k SAS drives in a hardware RAID6 array. Running 'iftop' on the machine during the data gathering operations, I'll see bursty traffic... that is to say, workstation -> NFS server traffic will be in the high 40mb/sec rate, then slow down, and once it slows down the device I refer to complains of dropped information then it'll speed up again. I find it hard to believe that a machine on the same (recent, gigabit) switch can't write out 4.7MB/sec. Am I wrong? Does anyone have any NFS or TCP tuning recommendations that may be a little more up to date than the NFS howto that was last updated in 2006? I'm really at a loss here. Thank you, more than a lot, in advance.. - Pat _______________________________________________ Tech mailing list Tech@lopsa.org http://lopsa.org/cgi-bin/mailman/listinfo/tech This list provided by the League of Professional System Administrators http://lopsa.org/ IMPORTANT: This email remains the property of the Department of Defence and is subject to the jurisdiction of section 70 of the Crimes Act 1914. If you have received this email in error, you are requested to contact the sender and delete the email. _______________________________________________ Tech mailing list Tech@lopsa.org http://lopsa.org/cgi-bin/mailman/listinfo/tech This list provided by the League of Professional System Administrators http://lopsa.org/
