From owner-freebsd-scsi Fri Oct 18 15:41:24 2002 Delivered-To: freebsd-scsi@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 11E6437B401 for ; Fri, 18 Oct 2002 15:41:23 -0700 (PDT) Received: from rootlabs.com (root.org [67.118.192.226]) by mx1.FreeBSD.org (Postfix) with SMTP id A73F443EA9 for ; Fri, 18 Oct 2002 15:41:22 -0700 (PDT) (envelope-from nate@rootlabs.com) Received: (qmail 47510 invoked by uid 1000); 18 Oct 2002 22:41:24 -0000 Date: Fri, 18 Oct 2002 15:41:24 -0700 (PDT) From: Nate Lawson To: Joerg Wunsch Cc: freebsd-scsi@freebsd.org Subject: Re: Multiple FreeBSD SCSI Hosts In-Reply-To: <200210182012.g9IKCHoI059995@uriah.heep.sax.de> Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-freebsd-scsi@FreeBSD.ORG Precedence: bulk List-ID: List-Archive: (Web Archive) List-Help: (List Instructions) List-Subscribe: List-Unsubscribe: X-Loop: FreeBSD.org On Fri, 18 Oct 2002, Joerg Wunsch wrote: > Mike Thompson wrote: > > > I'm interested in setting up two FreeBSD systems in a very simple > > clustering type configuration around centralized external SCSI storage > > devices for hardware redundancy. The specific configuration I'm thinking > > about is shown in the simple diagram below: > > > > +-----------+ +----------+ +-----------+ > > | FreeBSD | | | | FreeBSD | > > | Host 1 | | External | | Host 2 | > > | (primary) | | SCSI | |(secondary)| > > | | |RAID/DRIVE| | | > > | SCSI r/w | | | | SCSI r/o | > > +-----+-----+ +---+--+---+ +-----+-----+ > > | | | | > > +---------------+ +---------------+ > > Btw., we run it at a customer's site with two Sun servers, and > experience shows this is fairly fragile. It frequently causes > SCSI bus problems, like bus resets and lockups. > > We did it for that customer because they didn't want to spend the > money on a full-featured cluster solution. We wouldn't do it again, > at least not with parallel SCSI. (SCSI over fibre channel presumably > doesn't cause the class of problems we're seeing there.) What are you trying to achieve? If you are trying to have apps on two boxes sharing data via this method (say a webserver cluster), you're going to end up with consistency problems from the FILE SYSTEM. SCSI is not the problem -- multiple initiators have been around forever. The only way this would work is if both mounted the drive R/O or you use a filesystem that is aware of this type of scenario (i.e. joerg mentioning GFS). -Nate To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-scsi" in the body of the message