Date: Fri, 13 Sep 2002 16:58:00 -0500 From: Steve Fettig <lists@stevenfettig.com> To: net@freebsd.org Subject: Network Transfer Speed Issues - Tweaks/Advice? Message-ID: <DEC874D3-C763-11D6-9524-00039384AB84@stevenfettig.com>
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Hi, I already asked this one in questions thinking that I should try there before hitting the net list. Since I haven't received any responses, I was hoping someone here might have a clue. I recently set up an NFS server to run daily backups on. The server was built using an old P150 w/ 90 MB of ram and a 6GB hard drive. (All servers in this experiment are set up using FBSD 4.6.2 and the client is a Mac PowerBook G4 running Mac OS X.) Attached to it is an external SCSI hard drive enclosure with 4 47GB SCSI drives running off an AHA-2490UW SCSI adapter. I am getting really odd performance when doing an NFS transfer (I also get odd performance out of scp) from the machine I am trying to back up. I will get a burst of 20Mbps for about 30 seconds, then it will ramp down to 1 Mbps for about 2 minutes, ramp backup to 20 Mbps, then back down to 1 Mbps and so on. It take absolutely forever to do any high volume transfer at this rate. I originally thought it was a faulty NIC, so I swapped out my 3Com 509B Fast Etherlink card for an Intel Pro 10/100 card. The switch between cards and also between PCI slots has made no difference. When I run the same setup on a PIII 1GHz machine, the results are completely different. I get average transfer rates of 20-40 Mbps between the client and server using the same ethernet hardware. I have also set up another test on a dual PII-450 and have the same luck as with the PIII 1 GHz machine. This is using the same network cables and adapters, but between faster machines. I don't have any other services other than NFS running on the old P150, so I don't understand what would be the root of the problem. Is there something I can tweak in the kernel config that would help me attain higher, consistent throughput or am I out of luck with the older machine? (By the way, soft updates are enabled on all of the machines. MaxUsers is set to 0 on the P150 and to 128 on the PIII 1 GHz, but from what I have read in the Handbook, setting MaxUsers to 0 only helps the system decide what is best given the current configuration.) If needed I can also attach my current kernel config... Thanks, Steve To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-net" in the body of the message
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