Date: Thu, 10 Oct 2002 16:35:46 +0200 (CEST) From: "Hartmann, O." <ohartman@klima.physik.uni-mainz.de> To: Bill Moran <wmoran@potentialtech.com> Cc: freebsd-questions@freebsd.org, <freebsd-stable@freebsd.org> Subject: Re: NFS server not respnding! Message-ID: <20021010163107.P68233-100000@klima.physik.uni-mainz.de> In-Reply-To: <3DA58751.1020902@potentialtech.com>
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On Thu, 10 Oct 2002, Bill Moran wrote: Hello Bill. :>Hartmann, O. wrote: :>> Dear Sirs. :>> :>> Using FreeBSD 4.6.2-pl2 and FreeBSD 4.7-RC2 on our server system (one 4.7-RC :>> experimental system) and utilizing AMD for mounting home space and other :>> services via TCP protocol results in :>> :>> nfs server 134.93.180.216:/usr/homes: not responding :>> nfs server 134.93.180.216:/usr/homes: is alive again :>> :>> very often, when load of the appropriate client is very high. That happens :>> when on our number crunching systems utilization of CPU time is high or :>> many users try copy from and to via SAMBA to the main NFS server system. :> :>Yup. Happens because either the server or the network is swamped and some :>NFS packets are not being responded to as quickly as the client expects. :> :>Other than being annoying, it's not really a major problem. Well, it seems to _be_ a major problem due to breaking copy actions from Windows clients over SAMBA when NFS server is not respondig. I still __use__ TCP for the NFS connections, especially for all AMD mounts. Since tcp has been choosen as the main protocoll, those problems occur. I think something has to be changed to make all clients waiting a little bit for the server. The only real tweak would be to swap over to GigaBit LAN within our server system room to avoid the traffice bottleneck between the serving systems (we have a really misconfigured network and it makes it really hard to deal with a suitable topology - at the moment all traffic goes twice through our FreeBSD/PicoBSD filtering bridge). Thanks. :> :>> This happens under heavy load and, when only a few users are on the systems, :>> but it happens very often while :>> :>> - copying big files/datas from PC systems via SAMBA :>> - whenever a number crunching job runs on a different server :>> and on another server a job for copying data has been started, :>> the influences to a completely different system, in this case the main :>> NFS server, is significant. :>> :>> FreeBSD offers a lot of kernel stuff tunig the system's performance, :>> especially for NFS etc (also sysctl changeable kernel varibales). :>> Can anyone help with tuned parameters or give hints how to :>> investigate problems? :> :>Search the mailing list archives. This was discussed some months back, :>and someone provided info on which knobs to tweak to make the messages :>go away, along with the possible pitfalls of tweaking those knobs. :> :>> What's about the fact running AMD/NFS over TCP instead of UDP? UDP :>> seems to give the benefit of speed, while TCP seems to be more :>> reliable and secure from the point of view from the network. :> :>I don't think switching to TCP will stop this. To my knowledge, TCP :>connections only improve reliability over sketchy connections (such :>as WANs) My experience with NFS/TCP has been that it doesn't really :>improve reliability that much either (although we were dealing with :>an _extremely_ flakey wireless WAN - nothing was reliable) :> :>-- :>Bill Moran :>Potential Technologies :>http://www.potentialtech.com :> :> -- MfG O. Hartmann ohartman@klima.physik.uni-mainz.de ------------------------------------------------------------------ IT-Administration des Institutes fuer Physik der Atmosphaere (IPA) ------------------------------------------------------------------ Johannes Gutenberg Universitaet Mainz Becherweg 21 55099 Mainz Tel: +496131/3924662 (Maschinenraum) Tel: +496131/3924144 (Buero) FAX: +496131/3923532 To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-stable" in the body of the message
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