From owner-freebsd-questions Sun Jul 18 1:26:18 1999 Delivered-To: freebsd-questions@freebsd.org Received: from mojave.lemis.com (mojave.lemis.com [192.109.197.162]) by hub.freebsd.org (Postfix) with ESMTP id 7E33B14BE0 for ; Sun, 18 Jul 1999 01:26:05 -0700 (PDT) (envelope-from grog@lemis.com) Received: (grog@localhost) by mojave.lemis.com (8.9.3/8.6.12) id KAA00315; Sun, 18 Jul 1999 10:02:54 +0930 (CST) Message-ID: <19990718100214.53907@mojave.lemis.com> Date: Sun, 18 Jul 1999 10:02:14 +0930 From: Greg Lehey To: Walter Hafner Cc: Walter Hafner , questions@FreeBSD.ORG Subject: Re: strange NFS problem References: <14218.4014.47678.998590@hprbg5.informatik.tu-muenchen.de> <19990713112452.U21403@freebie.lemis.com> <14218.63691.589830.15439@hprbg5.informatik.tu-muenchen.de> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii X-Mailer: Mutt 0.89i In-Reply-To: <14218.63691.589830.15439@hprbg5.informatik.tu-muenchen.de>; from Walter Hafner on Tue, Jul 13, 1999 at 10:28:59AM +0200 WWW-Home-Page: http://www.lemis.com/~grog Organization: LEMIS, PO Box 460, Echunga SA 5153, Australia Phone: +61-8-8388-8286 Fax: +61-8-8388-8725 Mobile: +61-41-739-7062 Sender: owner-freebsd-questions@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG On Tuesday, 13 July 1999 at 10:28:59 +0200, Walter Hafner wrote: > Thanks for your help. Here's a little more info to clarify things: > >> On Monday, 12 July 1999 at 17:54:22 +0200, Walter Hafner wrote: >>> Host A: FreeBSD 2.2.8 STABLE, NFS Server >>> Host B: FreeBSD 3.1 RELEASE, NFS Client >>> >>> When I do a >>> >>> mount /mount/w3proj1/export/data >>> >>> on B it hangs forever. When I start mountd with -d on A, it tells me >>> "mount successful" or something similar (don't have the machine at >>> hand.) >> >> Is system B multi-homed? In other words, does it have more than one >> IP address? There's a bug in the system which will cause it to accept >> the mount, but possibly reply with the "other" IP address. This will >> cause a hang which you can only resolve with a reboot. See PR >> kern/9612 for more details. > > "A", the NFS _server_ is multi-homed. It answers to 6 IP-addresses and > about 15 names. Ah. It wasn't quite clear from your description which way round things run. Yes, this still sounds like the same scenario. Note that the DNS doesn't have anything to do with the problem, except to possibly confuse things further. > I know, what you want to say now ("NFS is Bad(tm) for WWW machines"), Well, I won't say that. > I mounted from the DNS-Server CNAME, not from the primary name. As I said, the DNS is not important. The IP addresses are. >>> Never mind. I found the problem (apart from the bogus "2" option in >>> /etc/fstab :-) >>> >>> I didn't mount from the machines "A" record name, but from on of the >>> machines "CNAME"s. The FreeBSD 3.1 mount doesn't seem to like this. >> >> If my reasoning above is correct, I don't think that's the solution, >> unless by changing the name you removed the duplicate IP addresses. > > I don't quite understand, what you mean by "removed the duplicate IP > addresses". All addresses are still valid. I'm no kernel hacker. All I > can say is: it works now. I tried both configurations (mountpoints) and > can repeat the behaviour at any time. The problem appears to be: you do a DNS lookup and get a random IP out of the ones to which the name answers. You send a mount request to this address. The request gets accepted, but the answer comes from the IP address of the interface to the network on which the reply is sent. Since B isn't looking for that, it rejects it and hangs on the original reply. > Looks like the behaviour you describe in 9612. I can especcially verify > this part: > > : Here the mount succeeds on the server side, but the reply contains the > : address 192.109.197.137, not 139.130.136.133, and is thus rejected by > : panic. The mount process hangs in sbwait and is not stoppable. > > But it seems to me, that mounts from the name in the "A" record always > succeed. Remember, it has nothing to do with the names. > If I can be any help in tracking the bug down, I'll help. Thanks, but we've tracked down the problem. The real question is, how do we fix it? I'm looking at that, but I need enough time to investigate. Greg -- Finger grog@lemis.com for PGP public key See complete headers for address and phone numbers To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-questions" in the body of the message