From owner-freebsd-fs Sat Apr 27 7:20:35 2002 Delivered-To: freebsd-fs@freebsd.org Received: from internal.mail.telinco.net (internal.mail.telinco.net [212.1.128.4]) by hub.freebsd.org (Postfix) with ESMTP id 2C80237B41B; Sat, 27 Apr 2002 07:20:30 -0700 (PDT) Received: from ppp-dp1-mk-66.access.uk.worldonline.com ([212.74.113.66] helo=vaio.linnet.org) by internal.mail.telinco.net with esmtp (Exim 3.22 #1) id 171T3s-000CBP-00; Sat, 27 Apr 2002 15:20:28 +0100 Received: (from brian@localhost) by vaio.linnet.org (8.9.3/8.9.3) id PAA16666; Sat, 27 Apr 2002 15:27:19 +0100 Date: Sat, 27 Apr 2002 15:27:18 +0100 From: Brian Candler To: "Andrew P. Lentvorski" Cc: freebsd-fs@freebsd.org, freebsd-net@freebsd.org Subject: Re: NFS clearing attribute cache in nfs_open Message-ID: <20020427152718.A16634@linnet.org> References: <20020426181535.B2748@linnet.org> <20020426162442.N8693-100000@mail.allcaps.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii X-Mailer: Mutt 1.0pre3us In-Reply-To: <20020426162442.N8693-100000@mail.allcaps.org> Sender: owner-freebsd-fs@FreeBSD.ORG Precedence: bulk List-ID: List-Archive: (Web Archive) List-Help: (List Instructions) List-Subscribe: List-Unsubscribe: X-Loop: FreeBSD.org On Fri, Apr 26, 2002 at 04:42:48PM -0700, Andrew P. Lentvorski wrote: > > ... Could it safely be made less restrictive, e.g. don't > > clear the cache when opening a file for read? > > In a word, no. Why couldn't the sysadmin be running "make installworld" > on the NFS server while you're running that program? By definition, for > better or worse, NFS is "stateless". The only way in which NFS can know > that your file hasn't changed (been deleted, renamed, etc) is to make that > round trip to the server. Sorry. Sounds fair. I was talking about the _attribute_ cache, but does re-fetching the attributes also tell the client that the _content_ of a file has changed? A version number, perhaps? > If you are really > into clusters with low-latency, you might want to look into something like > NFS V4 (Is anybody working on that on FreeBSD, anymore?), AFS, CODA, or > something more specialized. Those networked filesystems have a > bidrectional characteristic and cached state protocols so that they can > minimize communication. Will do. For a diskless bootup I think I am restricted to either NFS or ramdisk for the root filesystem though. Is it possible to replace the root filesystem with a different one after the system has started? Regards, Brian. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-fs" in the body of the message