From mboxrd@z Thu Jan 1 00:00:00 1970 From: James Bottomley Subject: Re: Is there a grand plan for FC failover? Date: 29 Jan 2004 10:05:45 -0500 Sender: linux-scsi-owner@vger.kernel.org Message-ID: <1075388747.2381.36.camel@mulgrave> References: <3356669BBE90C448AD4645C843E2BF2802C013B0@xbl.ma.emulex.com> <1075328212.2534.14.camel@mulgrave> <20040129094910.F11527@vienna.EGENERA.COM> Mime-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 7bit Return-path: Received: from stat1.steeleye.com ([65.114.3.130]:53955 "EHLO hancock.sc.steeleye.com") by vger.kernel.org with ESMTP id S266176AbUA2PF5 (ORCPT ); Thu, 29 Jan 2004 10:05:57 -0500 In-Reply-To: <20040129094910.F11527@vienna.EGENERA.COM> List-Id: linux-scsi@vger.kernel.org To: "Philip R. Auld" Cc: "Smart, James" , 'Patrick Mansfield' , Simon Kelley , SCSI Mailing List , dm-devel@sistina.com On Thu, 2004-01-29 at 09:49, Philip R. Auld wrote: > It needs to be known to the pathing layer if you've got load balancing. > It has to know which path has the reservation and only use that one. Well, yes, but your multiple active path implementation just collapsed back down to single path in the face of reservations, so it would probably be better simply to use failover in the face of reservations and clustering. For the single path case, something like the HP MSA/EVA arrays simply throw away reservations on path switch over. This allows the user level watchdog code to reassert them in a cluster down the new path. However, there are array that will do a path switchover and then return reservation conflict to everyone (including the taking node). These arrays will need some type of special handling. James