From owner-freebsd-questions Fri Oct 18 11:46:30 2002 Delivered-To: freebsd-questions@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id A605037B401 for ; Fri, 18 Oct 2002 11:46:28 -0700 (PDT) Received: from mail.atomz.com (MAIL.ATOMZ.COM [64.41.153.19]) by mx1.FreeBSD.org (Postfix) with ESMTP id 6280443EAF for ; Fri, 18 Oct 2002 11:46:28 -0700 (PDT) (envelope-from mike@atomz.com) Received: from mthompson.atomz.com (unknown [208.131.120.194]) by mail.atomz.com (Postfix) with ESMTP id 453C13075B for ; Fri, 18 Oct 2002 11:54:39 -0700 (PDT) Message-Id: <4.3.2.7.2.20021018114625.00c974a0@pop.atomz.com> X-Sender: mike@pop.atomz.com X-Mailer: QUALCOMM Windows Eudora Version 4.3.2 Date: Fri, 18 Oct 2002 11:46:59 -0700 To: freebsd-questions@FreeBSD.ORG From: Mike Thompson Subject: Multiple FreeBSD SCSI Hosts Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii"; format=flowed Sender: owner-freebsd-questions@FreeBSD.ORG Precedence: bulk List-ID: List-Archive: (Web Archive) List-Help: (List Instructions) List-Subscribe: List-Unsubscribe: X-Loop: FreeBSD.ORG 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 | +-----+-----+ +---+--+---+ +-----+-----+ | | | | +---------------+ +---------------+ There would be two FreeBSD systems with the primary server mounting the external SCSI storage read-write and the secondary server mounting the external SCSI storage read-only. Each server would have non-shared /, /usr and /var partitions on local drives. In a fail over situation, I would manually power down the primary server and re-mount the SCSI storage read-write on the secondary server to continue operation. My questions about this are as follows: 1. Do the FreeBSD SCSI drivers support such a configuration by implementing the SCSI RESERVE/RELEASE commands to lock access to the SCSI bus? If so, which drivers for which specific SCSI adapters? 2. Many external raid controllers describe themselves as host dual capability. Is the type of configuration they are describing? 3. Will the secondary server still experience a corrupted file system because of write caching by the primary server? If so, would it be possible to configure the primary server to write through the cache? 4. Are there any FreeBSD specific projects or ports that would make such a dual host SCSI configuration easier to configure or maintain? 5. What am I overlooking in such a configuration? 6. Are there alternatives to this type of scenario that may work better for FreeBSD? 7. Finally, are there resources already on the web that would answer these questions for me? I would be very much interested in hearing if other people have attempted such a configuration with FreeBSD servers and their experience. Also, specific hardware recommendations would be helpful. Thanks, Mike Thompson mike@atomz.com To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-questions" in the body of the message