From owner-freebsd-hackers Thu Oct 10 10:28:39 2002 Delivered-To: freebsd-hackers@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 1EE9137B401 for ; Thu, 10 Oct 2002 10:28:38 -0700 (PDT) Received: from dan.emsphone.com (dan.emsphone.com [199.67.51.101]) by mx1.FreeBSD.org (Postfix) with ESMTP id 7CF9943EA9 for ; Thu, 10 Oct 2002 10:28:36 -0700 (PDT) (envelope-from dan@dan.emsphone.com) Received: (from dan@localhost) by dan.emsphone.com (8.12.6/8.12.5) id g9AHSa37027306; Thu, 10 Oct 2002 12:28:36 -0500 (CDT) (envelope-from dan) Date: Thu, 10 Oct 2002 12:28:35 -0500 From: Dan Nelson To: Attila Nagy Cc: hackers@FreeBSD.ORG Subject: Re: Sharing a SCSI bus between some computers Message-ID: <20021010172835.GA24603@dan.emsphone.com> References: Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-OS: FreeBSD 5.0-CURRENT X-message-flag: Outlook Error User-Agent: Mutt/1.5.1i Sender: owner-freebsd-hackers@FreeBSD.ORG Precedence: bulk List-ID: List-Archive: (Web Archive) List-Help: (List Instructions) List-Subscribe: List-Unsubscribe: X-Loop: FreeBSD.ORG In the last episode (Oct 10), Attila Nagy said: > Due to the lack of enough "networking power" I started to think about > alternatives. > [ snip pic of SCSI RAID with 3 servers hanging off it ] > > The question is: what will happen if BOX3 mounts the filesystem from > the SCSI BOX RW and BOX[1-2] mount it RO? > > In the case BOX[1-2] it is only necessary to read from the array, > nothing more. As long as BOX3 never writes data, you're okay. The problem is that BOX1/2 don't know when BOX3 has invalidated their cached data by writing to the disk. What you want is a shared-storage filesystem, and there is no such thing for FreeBSD. Considering you can get a gigabit ethernet NIC for under $50 and a D-Link 4-port gigabit switch for $300, you might just want to plug the RAID into BOX3, and have BOX1/2 NFS-mount it. -- Dan Nelson dnelson@allantgroup.com To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message