Date: Fri, 18 Oct 2002 15:41:24 -0700 (PDT) From: Nate Lawson <nate@root.org> To: Joerg Wunsch <joerg_wunsch@uriah.heep.sax.de> Cc: freebsd-scsi@freebsd.org Subject: Re: Multiple FreeBSD SCSI Hosts Message-ID: <Pine.BSF.4.21.0210181535160.47484-100000@root.org> In-Reply-To: <200210182012.g9IKCHoI059995@uriah.heep.sax.de>
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On Fri, 18 Oct 2002, Joerg Wunsch wrote: > Mike Thompson <mike@atomz.com> 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
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