Date: Sun, 15 Sep 2002 20:21:34 -0400 From: Bill Moran <wmoran@potentialtech.com> To: Michael Ritchie <michaeljritchie@bigpond.com> Cc: questions@freebsd.org Subject: Re: SAMBA throughput increases when NIC bandwidth is decreased Message-ID: <3D85240E.5020904@potentialtech.com> References: <5.1.1.6.0.20020915183202.00b94808@mail.bigpond.com> <5.1.1.6.0.20020916071224.00b9e1e0@mail.bigpond.com>
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Keep the mailing list in the loop, please. Michael Ritchie wrote: > At 09:29 AM 15/09/2002 -0400, you wrote: > >> Michael Ritchie wrote: >> >>> I am running SAMBA 2.24 on a FreeBSD 4.6.2 box, a 1GHz PIII with >>> 256MB RAM and a nice big, fast scsi hard drive. My problem is that I >>> cannot get a decent amount of bandwidth out of it. I have tried >>> adjusting the smb.conf file, based on SPEED.TXT, but I still cannot >>> draw more than 300 or 400 k bytes/second out of it. I tried scaling >>> its ethernet switch port down from 100MBPS full duplex to 10half, and >>> the speed more than tripled -- up to 1200 kbytes / second. I can't >>> explain this --- help?? >>> I have also tried a variety of NICs, from 3com etherlink 905b to >>> Intel EtherExpress Pro100 and a D-Link card. All exhibit similar >>> behaviour, although not to the extent of the 3com. >> >> Sounds like a problem with the switch and/or autonegotiation. >> Set the switch back to 100mbs and check "ifconfig" on FreeBSD to ensure >> it is negotiating the correct speed/duplex. You may have to manually >> set it if it doesn't detect correctly. Bunged autonegotiation will cause >> lousy speeds. >> Verify that your wiring is up to spec! Out of spec wiring will cause >> higher speed transmission to have lots of problems. >> If all else fails, try a different port on the switch and see if the >> problem disappears. If that fails, try a different switch. > > Ok, I've checked ifconfig, and it says (at both ends) that the NIC is > negotiating a 100meg full duplex connection. Also brought up a telnet > session to the switch (a Cisco 2950). Also tried a 3com SuperStack II > switch, same problem. The cabling is up to spec -- it was installed > last week and I have the test results here in my hand -- it surpassed > Category 6 requirements. Have you established whether it's a Samba problem, FreeBSD problem, or network problem? Try some FTPs from one machine to the other and see if the problem exists with FTP as well. If so, that eliminates Samba as the culpret. Try setting net.inet.tcp.delayed_ack => 0 via sysctl. I don't think this is the problem, as I've never seen it cause the magnitude of slowdown that you're experiencing, but it's worth a try. Beyond that, I'm rather stumped. Your first message seems to show the hardware as the suspect (since you saw greater problems with the 3com card than with other cards) Perhaps check your interrupts for conflicts, or other hardware irregularities. More FreeBSD specific, use netstat to monitor the network while testing things. See if you're running out of mbufs, or perhaps you need to crank up net.inet.tcp.sendspace & net.inet.tcp.recvspace. These are all guesses and ideas on how to further isolate the problem. -- Bill Moran Potential Technologies http://www.potentialtech.com To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-questions" in the body of the message
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