Date: Sat, 18 Jan 2003 14:52:28 -0800 From: Lars Eggert <larse@ISI.EDU> To: Terry Lambert <tlambert2@mindspring.com> Cc: Scott Mitchell <scott.mitchell@mail.com>, Jay Sern Liew <jay@americanhorizonsbank.com>, freebsd-hackers@FreeBSD.ORG Subject: Re: 5400RPM|7200RPM Cable bottleneck? Message-ID: <3E29DAAC.5040707@isi.edu> In-Reply-To: <3E29D4D2.47A5E909@mindspring.com> References: <1042849118.3e289d5ee4458@webmail.americanhorizonsbank.com> <20030118105015.GB783@fishballoon.dyndns.org> <3E2998FD.1010904@isi.edu> <3E29D4D2.47A5E909@mindspring.com>
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This is a cryptographically signed message in MIME format. --------------ms060002010406070302020008 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit On 1/18/2003 2:27 PM, Terry Lambert wrote: > Lars Eggert wrote: > >>I've tried NFS mounting ISI servers at home over PPTP over a cable modem >>connection, and it's painfully slow - much slower than the bandwidth of >>the cable pipe. NFS isn't well tuned for high-RTT environments (in my >>case, 20ms). > > The up-channel speed on a cable modem is usually in the > neighborhood of 1.5 times the amount of bandwidth needed > for just the ACKs for the data coming down the down-channel; > that leaves very little bandwidth left over for NFS requests > to the server, particularly if there are a lot of data > transfers taking place from the server to the client (client > reads). If you are doing any level of data transfers from > the client to the server (client writes), you should expect > your performance to go to hell. Both uplink and downlink bandwidths are nowhere near saturation - it's the underlying RPC that make NFS inherently slow over WAN links. Lars -- Lars Eggert <larse@isi.edu> USC Information Sciences Institute --------------ms060002010406070302020008 Content-Type: application/x-pkcs7-signature; name="smime.p7s" Content-Transfer-Encoding: base64 Content-Disposition: attachment; filename="smime.p7s" Content-Description: S/MIME Cryptographic Signature MIAGCSqGSIb3DQEHAqCAMIACAQExCzAJBgUrDgMCGgUAMIAGCSqGSIb3DQEHAQAAoIIJtjCC AzgwggKhoAMCAQICEGZFcrfMdPXPY3ZFhNAukQEwDQYJKoZIhvcNAQEEBQAwgdExCzAJBgNV BAYTAlpBMRUwEwYDVQQIEwxXZXN0ZXJuIENhcGUxEjAQBgNVBAcTCUNhcGUgVG93bjEaMBgG A1UEChMRVGhhd3RlIENvbnN1bHRpbmcxKDAmBgNVBAsTH0NlcnRpZmljYXRpb24gU2Vydmlj ZXMgRGl2aXNpb24xJDAiBgNVBAMTG1RoYXd0ZSBQZXJzb25hbCBGcmVlbWFpbCBDQTErMCkG CSqGSIb3DQEJARYccGVyc29uYWwtZnJlZW1haWxAdGhhd3RlLmNvbTAeFw0wMDA4MzAwMDAw MDBaFw0wNDA4MjcyMzU5NTlaMIGSMQswCQYDVQQGEwJaQTEVMBMGA1UECBMMV2VzdGVybiBD YXBlMRIwEAYDVQQHEwlDYXBlIFRvd24xDzANBgNVBAoTBlRoYXd0ZTEdMBsGA1UECxMUQ2Vy dGlmaWNhdGUgU2VydmljZXMxKDAmBgNVBAMTH1BlcnNvbmFsIEZyZWVtYWlsIFJTQSAyMDAw 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