From owner-freebsd-hackers@FreeBSD.ORG  Mon Apr 30 05:09:47 2012
Return-Path: <owner-freebsd-hackers@FreeBSD.ORG>
Delivered-To: freebsd-hackers@freebsd.org
Received: from mx1.freebsd.org (mx1.freebsd.org [69.147.83.52])
	by hub.freebsd.org (Postfix) with ESMTP id 7862A1065673
	for <freebsd-hackers@freebsd.org>; Mon, 30 Apr 2012 05:09:47 +0000 (UTC)
	(envelope-from wojtek@wojtek.tensor.gdynia.pl)
Received: from wojtek.tensor.gdynia.pl (wojtek.tensor.gdynia.pl [89.206.35.99])
	by mx1.freebsd.org (Postfix) with ESMTP id D54AD8FC0C
	for <freebsd-hackers@freebsd.org>; Mon, 30 Apr 2012 05:09:46 +0000 (UTC)
Received: from wojtek.tensor.gdynia.pl (localhost [127.0.0.1])
	by wojtek.tensor.gdynia.pl (8.14.5/8.14.5) with ESMTP id q3U59iTp030264;
	Mon, 30 Apr 2012 07:09:44 +0200 (CEST)
	(envelope-from wojtek@wojtek.tensor.gdynia.pl)
Received: from localhost (wojtek@localhost)
	by wojtek.tensor.gdynia.pl (8.14.5/8.14.5/Submit) with ESMTP id
	q3U59hg5030261; Mon, 30 Apr 2012 07:09:44 +0200 (CEST)
	(envelope-from wojtek@wojtek.tensor.gdynia.pl)
Date: Mon, 30 Apr 2012 07:09:43 +0200 (CEST)
From: Wojciech Puchar <wojtek@wojtek.tensor.gdynia.pl>
To: Rick Macklem <rmacklem@uoguelph.ca>
In-Reply-To: <1715805628.104139.1335733226336.JavaMail.root@erie.cs.uoguelph.ca>
Message-ID: <alpine.BSF.2.00.1204300708060.30254@wojtek.tensor.gdynia.pl>
References: <1715805628.104139.1335733226336.JavaMail.root@erie.cs.uoguelph.ca>
User-Agent: Alpine 2.00 (BSF 1167 2008-08-23)
MIME-Version: 1.0
Content-Type: TEXT/PLAIN; charset=US-ASCII; format=flowed
X-Greylist: Sender passed SPF test, not delayed by milter-greylist-4.2.7
	(wojtek.tensor.gdynia.pl [127.0.0.1]);
	Mon, 30 Apr 2012 07:09:44 +0200 (CEST)
Cc: freebsd-hackers@freebsd.org
Subject: Re: NFS - slow
X-BeenThere: freebsd-hackers@freebsd.org
X-Mailman-Version: 2.1.5
Precedence: list
List-Id: Technical Discussions relating to FreeBSD
	<freebsd-hackers.freebsd.org>
List-Unsubscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-hackers>, 
	<mailto:freebsd-hackers-request@freebsd.org?subject=unsubscribe>
List-Archive: <http://lists.freebsd.org/pipermail/freebsd-hackers>
List-Post: <mailto:freebsd-hackers@freebsd.org>
List-Help: <mailto:freebsd-hackers-request@freebsd.org?subject=help>
List-Subscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-hackers>,
	<mailto:freebsd-hackers-request@freebsd.org?subject=subscribe>
X-List-Received-Date: Mon, 30 Apr 2012 05:09:47 -0000

> the server is required to do that. (ie. Make sure the data is stored on
> stable storage, so it can't be lost if the server crashes/reboots.)
> Expensive NFS servers can use non-volatile RAM to speed this up, but a generic
> FreeBSD box can't do that.
>
> Some clients (I believe ESXi is one of these) requests FILE_SYNC all the
> time, but all clients will do so sooner or later.
>
> If you are exporting ZFS volumes and don't mind violating the NFS RFCs
> and risking data loss, there is a ZFS option that helps. I don't use
> ZFS, but I think the option is (sync=disabled) or something like that.
> (ZFS folks can help out, if you want that.) Even using vfs.nfsrv.async=1
> breaks the above.


thank you for answering. i don't use or plan to use ZFS. and i am aware of 
this NFS "feature" but i don't understand - even with syncs disabled, why 
writes are not clustered. i always see 32kB writes in systat


when running unfsd from ports it doesn't have that problem and works 
FASTER than kernel nfs.