Date: Tue, 15 Dec 1998 10:10:16 -0500 (EST) From: Charles Owens <owensc@enc.edu> To: hackers@FreeBSD.ORG Subject: Re: NFS thoughts Message-ID: <Pine.BSF.3.96.981215092411.2552B-100000@itsdsv2.enc.edu>
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On Mon, 14 Dec 1998, Bernd Walter wrote:
> I saw the same on my private hosts.
> Everythings the same to your case instead that I have a 100MBit FreeBSD Router
> between them. All lines are running Full-Duplex Point-to-Point.
> In my case I have a syslogentry telling me about a server down under some load
> and it took minutes till it says that the server is up again.
> It happend when using NFS3/TCP at this moment I'm using NFS2/UDP and it won't
> hang.
I was at the Usenix LISA conference last week and in one of the
tutorials the issue of NFSv3/TCP stability and interoperability came
up.
One user reported the SGI<->Solaris and even SGI<->SGI NFSv3 mounts
were flakey (with similar symptoms as described here). He eventually
traced the problem to the NFSv3/TCP's use of larger buffersizes.
These result in more intense bursts of network activity which would at
times overrun buffers in his Ethernet switch. He convinced his
network vendor to replace the switch with another with deeper buffers,
and his problem went away!
With the original switch he found that the default 32K read/write
buffer size (as compared to UDP's default of 8K) was too much, but by
limiting it to 16K he was able to get by, but with some reduction in
performance.
Could this be the issue that is plaguing our attempts to use NFSv3
with FreeBSD? Or are there other known defects that are at fault.
I'm guessing that with FreeBSD we'd use the -r and -w options of mount_nfs
to limit the read and write buffer sizes, though the manpage description
isn't quite as informative as what's provided with the Solaris:
rsize=n Set the read buffer size to n bytes.
The default value is 32768 when using
Version 3 of the NFS protocol. When
using Version 2, the default value is
8192.
Does this mount_nfs option from Solaris indeed work the same way as
FreeBSD's -r option?
later,
---
-------------------------------------------------------------------------
Charles N. Owens Email: owensc@enc.edu
http://www.enc.edu/~owensc
Network & Systems Administrator
Information Technology Services "Outside of a dog, a book is a man's
Eastern Nazarene College best friend. Inside of a dog it's
too dark to read." - Groucho Marx
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