Date: Tue, 8 May 2007 19:21:07 GMT From: Seraphi<seraphi.lord@gmail.com> To: freebsd-gnats-submit@FreeBSD.org Subject: amd64/112528: NFS over TCP under load hangs with "impossible packet length" Message-ID: <200705081921.l48JL7gO030815@www.freebsd.org> Resent-Message-ID: <200705081930.l48JU6ZT007773@freefall.freebsd.org>
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>Number: 112528 >Category: amd64 >Synopsis: NFS over TCP under load hangs with "impossible packet length" >Confidential: no >Severity: serious >Priority: high >Responsible: freebsd-amd64 >State: open >Quarter: >Keywords: >Date-Required: >Class: sw-bug >Submitter-Id: current-users >Arrival-Date: Tue May 08 19:30:05 GMT 2007 >Closed-Date: >Last-Modified: >Originator: Seraphi >Release: 6.2-RELEASE-p4 >Organization: >Environment: FreeBSD nfsclient05.domain.com 6.2-RELEASE-p4 FreeBSD 6.2-RELEASE-p4 #0: Tue May 8 13:59:19 EDT 2007 admin@nfsclient05.domain.com:/usr/obj/usr/src/sys/MYKERN_62_05042007 amd64 >Description: NFS over UDP will hang under load and throw the following errors to syslog: May 8 14:36:55 nfsclient05 kernel: impossible packet length (13050202) from nfs server 192.168.101.12:/store22 May 8 14:36:56 nfsclient05 kernel: impossible packet length (1669907873) from nfs server 192.168.101.12:/store22 May 8 14:37:01 nfsclient05 kernel: impossible packet length (46381) from nfs server 192.168.101.12:/store22 I have tried many mount options, but here is one set that will have this problem: 192.168.101.12:/store22 /s22 nfs ro,-i,-b,-3,-T,-r=16384,-w=16384 0 0 To get the error to occur, I simply copy a multi-gig file from NFS to a local drive. It happens very frequently. I have only tried this on gigabit networks. The error goes away if I use UDP, which is what I am using until this is fixed. I have tried this on FreeBSD 6.1 as well and had the same problem. I have also tried a different NFS server running a different OS on a different network with a different configuration on different hardware. It did not help. I have tried updating with freebsd-update but the status is unchanged. >How-To-Repeat: Put an NFS client and server on a gigabit network. Mount the server using TCP: 192.168.101.12:/store22 /s22 nfs ro,-i,-b,-3,-T,-r=16384,-w=16384 0 0 Copy a large file (1GB+) from the NFS mount to a local drive. Do this a couple of times, then check /var/log/messages >Fix: Use UDP: 192.168.101.12:/store22 /s22 nfs ro,-i,-b,-3,-U,-r=16384,-w=16384 0 0 >Release-Note: >Audit-Trail: >Unformatted:
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