Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!sdd.hp.com!think.com!hsdndev!cmcl2!kramden.acf.nyu.edu!brnstnd
From: brnstnd@kramden.acf.nyu.edu (Dan Bernstein)
Newsgroups: comp.unix.wizards
Subject: Re:  Re:  Another reason I hate NFS: Silent data loss!
Message-ID: <16703.Jun1903.07.1091@kramden.acf.nyu.edu>
Date: 19 Jun 91 03:07:10 GMT
References: <27226@adm.brl.mil>
Organization: IR
Lines: 22

In article <27226@adm.brl.mil> mike@BRL.MIL ( Mike Muuss) writes:
> NFS is designed as a reliable protocol.  I have pounded more than 250
> NFS requests/sec against a fileserver, and no data loss.

In this case the 20 requests came in under 1/50 of a second (somewhat
smaller, I think, but I don't have good measuring tools). I can't
sustain this load from one Sun, but a single burst was enough to lose
data.

> Things you
> should check are the number of retransmit's you authorized in /etc/fstab,

If the number of retransmits runs out, the writing process ``should''
get an error. Otherwise the implementation is (obviously) buggy.

> the error logs on both machines (run NFSSTAT), "netstat -s",

Nope. As far as I can tell, the loss was completely silent. I'm working
on a test program to exercise the problem thoroughly; I'll post it when
it's done.

---Dan