From owner-freebsd-current@FreeBSD.ORG Tue Mar 25 18:54:28 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 1023C37B404 for ; Tue, 25 Mar 2003 18:54:28 -0800 (PST) Received: from puffin.mail.pas.earthlink.net (puffin.mail.pas.earthlink.net [207.217.120.139]) by mx1.FreeBSD.org (Postfix) with ESMTP id 41AF843F93 for ; Tue, 25 Mar 2003 18:54:27 -0800 (PST) (envelope-from tlambert2@mindspring.com) Received: from pool0212.cvx21-bradley.dialup.earthlink.net ([209.179.192.212] helo=mindspring.com) by puffin.mail.pas.earthlink.net with asmtp (SSLv3:RC4-MD5:128) (Exim 3.33 #1) id 18y13W-0002gx-00; Tue, 25 Mar 2003 18:54:23 -0800 Message-ID: <3E81160B.E5406C60@mindspring.com> Date: Tue, 25 Mar 2003 18:52:59 -0800 From: Terry Lambert X-Mailer: Mozilla 4.79 [en] (Win98; U) X-Accept-Language: en MIME-Version: 1.0 To: Ian Dowse References: <200303260034.aa92057@salmon.maths.tcd.ie> Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit X-ELNK-Trace: b1a02af9316fbb217a47c185c03b154d40683398e744b8a465f495f30fd86d5121c6c9889e50269a3ca473d225a0f487350badd9bab72f9c350badd9bab72f9c X-Spam-Status: No, hits=-21.8 required=5.0 tests=AWL,EMAIL_ATTRIBUTION,QUOTED_EMAIL_TEXT, RCVD_IN_OSIRUSOFT_COM,RCVD_IN_UNCONFIRMED_DSBL,REFERENCES, REPLY_WITH_QUOTES autolearn=ham version=2.50 X-Spam-Level: X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) cc: current@freebsd.org Subject: [Re: NFS -current 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: Wed, 26 Mar 2003 02:54:29 -0000 X-List-Received-Date: Wed, 26 Mar 2003 02:54:29 -0000 Ian Dowse wrote: > In message <20030325210152.GA12565@argv.de>, Patric Mrawek writes: > >On several clients (-DP1, -DP2, 4-stable) mounting a nfs-share > >(mount_nfs -i -U -3 server:/nfs /mnt) and then copying data from that > >share to the local disk (find -x -d /mnt | cpio -pdumv /local) results > >in lost NFS-mount. > > > >client kernel: nfs server server:/nfs: not responding 10 > 9 > > I'm not sure what you mean by a "lost" mount. Do all further accesses > to the filesystem hang? > > It is normal enough to get the above 'not responding' errors > occasionally on a busy fileserver, but only if they are almost > immediately followed by 'is alive again' messages. Particularly when using UDP with a "rsize" or "wsize" larger than the MTU, which Linux people do all the time. As you are using UDP... "If you hear hoofbeats, look for horses first, not zebras". This is arguably a bug in the FreeBSD UDP packet reassembly code not throwing away packets through ageing. There's a DOS attack you can use against FreeBSD against UDP protocols with larger than MTU packets, knowing this. But I think it's more arguably a bug in people using UDP in a wrong-headed way, in order to try and get a window size larger that the MTU, without using a sliding window protocol like TCP instead, which is designed to handle this much more gracefully. -- Terry