From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mx1.redhat.com (ext-mx07.extmail.prod.ext.phx2.redhat.com [10.5.110.11]) by int-mx01.intmail.prod.int.phx2.redhat.com (8.13.8/8.13.8) with ESMTP id oAA0LT7Q029051 for ; Tue, 9 Nov 2010 19:21:29 -0500 Received: from cdptpa-omtalb.mail.rr.com (cdptpa-omtalb.mail.rr.com [75.180.132.120]) by mx1.redhat.com (8.13.8/8.13.8) with ESMTP id oAA0LE91015186 for ; Tue, 9 Nov 2010 19:21:14 -0500 Message-ID: <4CD9E579.8070507@cfl.rr.com> Date: Tue, 09 Nov 2010 19:21:13 -0500 From: Phillip Susi MIME-Version: 1.0 References: <4CD35D3E.5030200@cfl.rr.com> <4CD5F804.3040906@cfl.rr.com> In-Reply-To: Content-Transfer-Encoding: 7bit Subject: Re: [linux-lvm] LVM + raid + san Reply-To: LVM general discussion and development List-Id: LVM general discussion and development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , List-Id: Content-Type: text/plain; charset="us-ascii"; format="flowed" To: "Stuart D. Gathman" Cc: LVM general discussion and development On 11/09/2010 05:15 PM, Stuart D. Gathman wrote: > Actually, this would be an interesting driver to develop. If each > server primarily works on its own LV, then there shouldn't be much I think the existing dm raid driver would work for this; it just needs to be finished and integrated with lvm. Unlike mdadm, the dm raid driver is only activated on the physical extents of the physical volumes that make up the logical volume, rather than the whole disk or partition, so each host should be able to use the cluster locking daemon to make sure only one activates any given lv at a time. If a server goes down then another can activate the lv and take over. > It is an interesting idea to avoid a traditional SAN as a single point of > failure (the switch connecting the hosts and disks would still be a single > point of failure, but a switch is simpler than a SAN server). All hosts would > have to be trusted. And switches can be redundant. I understand that at least some sas drives have two redundant ports that can each be connected to a different expander and the servers can be connected to both expanders.