From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Philip R. Auld" Subject: Re: Is there a grand plan for FC failover? Date: Thu, 29 Jan 2004 09:49:10 -0500 Sender: linux-scsi-owner@vger.kernel.org Message-ID: <20040129094910.F11527@vienna.EGENERA.COM> References: <3356669BBE90C448AD4645C843E2BF2802C013B0@xbl.ma.emulex.com> <1075328212.2534.14.camel@mulgrave> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from roadrunner-base.egenera.com ([63.160.166.46]:12698 "EHLO coyote.egenera.com") by vger.kernel.org with ESMTP id S266122AbUA2Ovh (ORCPT ); Thu, 29 Jan 2004 09:51:37 -0500 Content-Disposition: inline In-Reply-To: <1075328212.2534.14.camel@mulgrave>; from James.Bottomley@steeleye.com on Wed, Jan 28, 2004 at 05:16:51PM -0500 List-Id: linux-scsi@vger.kernel.org To: James Bottomley Cc: "Smart, James" , 'Patrick Mansfield' , Simon Kelley , SCSI Mailing List , dm-devel@sistina.com Rumor has it that on Wed, Jan 28, 2004 at 05:16:51PM -0500 James Bottomley said: > On Wed, 2004-01-28 at 16:02, Smart, James wrote: > > I'd add one additional issue : > > > > 3) SCSI Reservations > > > > I guess this could be considered a part of (2), but given that reservations > > bring in a host of additional problems, and potentially brings up multi-host > > configs/clusters as well... > > The current crop of cluster implementations that use reservations manage > quite well in user space alone. Certainly, though, the presence of > reservations can interfere with failover code and may be considered a > problem that needs to be solved in multi-path...it all depends on how > the multi-path devices react to path switching in the face of > reservations. > 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. > I'm open to suggestions on this, but I think it should be done > separately as part of a device ownership API. > > James > -- Philip R. Auld, Ph.D. Egenera, Inc. Principal Software Engineer 165 Forest St. (508) 858-2628 Marlboro, MA 01752