From owner-freebsd-hackers@FreeBSD.ORG Wed Nov 9 21:25:35 2005 Return-Path: X-Original-To: freebsd-hackers@freebsd.org 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 33FCD16A41F; Wed, 9 Nov 2005 21:25:35 +0000 (GMT) (envelope-from djh@nebcorp.com) Received: from ratchet.nebcorp.com (ratchet.nebcorp.com [205.217.153.72]) by mx1.FreeBSD.org (Postfix) with ESMTP id 0902243D45; Wed, 9 Nov 2005 21:25:35 +0000 (GMT) (envelope-from djh@nebcorp.com) Received: by ratchet.nebcorp.com (Postfix, from userid 1014) id B2AFED9849; Wed, 9 Nov 2005 13:25:34 -0800 (PST) Date: Wed, 9 Nov 2005 13:25:34 -0800 From: Danny Howard To: freebsd-geom@freebsd.org, freebsd-hackers@freebsd.org Message-ID: <20051109212534.GD72876@ratchet.nebcorp.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.4.2.1i X-Loop: djhoward@uiuc.edu X-Mailman-Approved-At: Thu, 10 Nov 2005 05:23:46 +0000 Cc: Subject: GEOM for multipath? How? X-BeenThere: freebsd-hackers@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Technical Discussions relating to FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 09 Nov 2005 21:25:35 -0000 Hello, Alas, my fancy Engenio dual-FC disk array is inaccessible to me for testing. :( But we are working on switching over to RHEL due to availability of FC multi-path redundancy drivers for RHEL but nada for FreeBSD. I was reading Linux' md man page, which sounds awfully similar to geom, and they have a provider called: MUTIPATH MULTIPATH is not really a RAID at all as there is only one real device in a MULTIPATH md array. However there are multiple access points (paths) to this device, and one of these paths might fail, so there are some similarities. A MULTIPATH array is composed of a number of logical different devices, often fibre channel interfaces, that all refer the the same real device. If one of these interfaces fails (e.g. due to cable prob- lems), the multipath driver to attempt to redirect requests to another interface. And I says to myself "AHA! Multipath should be easy to implement on FreeBSD as well, via geom." But I can't find an obvious way given existing geom utils to do this. And like I said, the box I'd use this on is inaccesible for now. Basically, I'd want a provider, that would see two disks, and if it could talk to one disk, it would, else it would talk to the other. Anyone here have a multipath capable hardware infrastructure who could test out some applicable geom config? Like I say a third time ... I have a nice Engenio 2882 FC sitting in a Datacenter, 3,000 miles away, that is connected to a system that is offline. I get to visit after Thanksgiving ... :/ Thanks, -danny -- http://dannyman.toldme.com/