From owner-freebsd-questions@FreeBSD.ORG Thu Jul 20 13:53:46 2006 Return-Path: X-Original-To: freebsd-questions@freebsd.org 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 6A05416A4DA for ; Thu, 20 Jul 2006 13:53:46 +0000 (UTC) (envelope-from cswiger@mac.com) Received: from pi.codefab.com (pi.codefab.com [199.103.21.227]) by mx1.FreeBSD.org (Postfix) with ESMTP id E1F9443D46 for ; Thu, 20 Jul 2006 13:53:43 +0000 (GMT) (envelope-from cswiger@mac.com) Received: from localhost (localhost [127.0.0.1]) by pi.codefab.com (Postfix) with ESMTP id 587D05C35; Thu, 20 Jul 2006 09:53:43 -0400 (EDT) X-Virus-Scanned: amavisd-new at codefab.com Received: from pi.codefab.com ([127.0.0.1]) by localhost (pi.codefab.com [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id T7Boxc1lW5lk; Thu, 20 Jul 2006 09:53:42 -0400 (EDT) Received: from [192.168.1.251] (pool-68-161-117-245.ny325.east.verizon.net [68.161.117.245]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by pi.codefab.com (Postfix) with ESMTP id 381545C2E; Thu, 20 Jul 2006 09:53:42 -0400 (EDT) Message-ID: <44BF8ADD.5000906@mac.com> Date: Thu, 20 Jul 2006 09:53:33 -0400 From: Chuck Swiger User-Agent: Thunderbird 1.5.0.4 (Windows/20060516) MIME-Version: 1.0 To: Atom Powers References: In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: freebsd-questions Subject: Re: File System for attached storage? X-BeenThere: freebsd-questions@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: User questions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 20 Jul 2006 13:53:46 -0000 Atom Powers wrote: > All the modern storage cabinets have two data ports (mine has two > SCSI320 ports) so they can be attached to two servers. But what kind > of file system can you use that would make that data available to both > servers? > > Splitting the storage in half isn't an option, as that doesn't give > added redundancy. > > I've head of GFS and Coda, but I can't find any information about how > stable these file systems are on FreeBSD 6.x. > > What do/would you use to share a storage device between two servers? There's something in the SCSI and Firewire worlds called "target initiator mode" or "target mode", which lets you have multiple controllers on the same bus without direct conflict. This can be used to treat your laptop as if it were an external hard drive and work on it from another system. Or it can be used to share a tape drive between two machines, at least so long as only one computer is doing stuff at any particular time. Less commonly, it can be used for fault-tolerant hot-standby servers operating from a shared central storage. If you want that kind of thing, or if you want several computers to modify the same disks in parallel, you should look into fibre-channel or maybe iSCSI-based SAN solutions. These usually involve a bespoke filesystem and metadata controller mechanism to keep the filesystem sane-- something like a Qlogic FC-switch, an Apple Xsan, + ADIC StorEdge software, for example. -- -Chuck