From owner-freebsd-current@FreeBSD.ORG Thu Aug 28 02:31:25 2003 Return-Path: Delivered-To: freebsd-current@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id E596B16A4BF for ; Thu, 28 Aug 2003 02:31:25 -0700 (PDT) Received: from heron.mail.pas.earthlink.net (heron.mail.pas.earthlink.net [207.217.120.189]) by mx1.FreeBSD.org (Postfix) with ESMTP id 3E7F443FEC for ; Thu, 28 Aug 2003 02:31:25 -0700 (PDT) (envelope-from tlambert2@mindspring.com) Received: from user-2ivfk56.dialup.mindspring.com ([165.247.208.166] helo=mindspring.com) by heron.mail.pas.earthlink.net with asmtp (SSLv3:RC4-MD5:128) (Exim 3.33 #1) id 19sJ7j-0004NY-00; Thu, 28 Aug 2003 02:31:24 -0700 Message-ID: <3F4DCBB1.2BDA25AC@mindspring.com> Date: Thu, 28 Aug 2003 02:30:25 -0700 From: Terry Lambert X-Mailer: Mozilla 4.79 [en] (Win98; U) X-Accept-Language: en MIME-Version: 1.0 To: Jason Stone References: <20030827211535.N3417@walter> Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit X-ELNK-Trace: b1a02af9316fbb217a47c185c03b154d40683398e744b8a4c1925dc0754e423c99362a17e85478b0666fa475841a1c7a350badd9bab72f9c350badd9bab72f9c cc: freebsd-current@freebsd.org Subject: Re: nfs tranfers hang in state getblck or nfsread X-BeenThere: freebsd-current@freebsd.org X-Mailman-Version: 2.1.1 Precedence: list List-Id: Discussions about the use of FreeBSD-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 28 Aug 2003 09:31:26 -0000 Jason Stone wrote: > I'm also seeing a similar problem - I have a cluster of high-volume > mailservers delivering mail over nfs to maildirs on a netapp. The cluster > was all 4-stable, but I decided to mix a couple of 5.1 boxes in to see how > they would do. > > The 5.1 boxes accepted and queued mail as well as the 4-stable boxes, but > delivering the mail into the maildirs over nfs, I kept seeing those > short-lived hangs, and so the queues started to back up as the boxes were > accepting mail faster than they could deliver it. > > My mounts are all nfsv3 over udp. UDP has problems, if you lose any packets at all. The problem is that the packet reassembly buffer stays full until you retry, and the retry is out of band, for packets larger than the MTU size. What happens when you drop the read and write size low enough that the data and headers fit in a single UDP packet (e.g. according to "tcpdump")? Does it "suddenly" become more reliable? -- Terry