From mboxrd@z Thu Jan 1 00:00:00 1970 From: Chandra Seetharaman Subject: Re: [RFC][PATCH] Handle multipath paths in a path group properly during pg_init (was "RE: [dm-devel] DM does not activate the paths if there are more than one path in path group during failover") Date: Fri, 14 Nov 2008 12:24:46 -0800 Message-ID: <1226694286.8998.104.camel@chandra-ubuntu> References: <1225944321.14830.1109.camel@chandra-ubuntu> <20081111005920.GN16649@agk.fab.redhat.com> <1226620138.8998.64.camel@chandra-ubuntu> <20081114001205.GQ30569@agk.fab.redhat.com> <1226689728.8998.76.camel@chandra-ubuntu> <20081114193458.GV30569@agk.fab.redhat.com> Reply-To: sekharan@us.ibm.com Mime-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 7bit Return-path: Received: from e31.co.us.ibm.com ([32.97.110.149]:34951 "EHLO e31.co.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753015AbYKNUY4 (ORCPT ); Fri, 14 Nov 2008 15:24:56 -0500 Received: from d03relay04.boulder.ibm.com (d03relay04.boulder.ibm.com [9.17.195.106]) by e31.co.us.ibm.com (8.13.1/8.13.1) with ESMTP id mAEKO0dx002382 for ; Fri, 14 Nov 2008 13:24:00 -0700 Received: from d03av02.boulder.ibm.com (d03av02.boulder.ibm.com [9.17.195.168]) by d03relay04.boulder.ibm.com (8.13.8/8.13.8/NCO v9.1) with ESMTP id mAEKOt7D116486 for ; Fri, 14 Nov 2008 13:24:55 -0700 Received: from d03av02.boulder.ibm.com (loopback [127.0.0.1]) by d03av02.boulder.ibm.com (8.12.11.20060308/8.13.3) with ESMTP id mAEKOtej006518 for ; Fri, 14 Nov 2008 13:24:55 -0700 In-Reply-To: <20081114193458.GV30569@agk.fab.redhat.com> Sender: linux-scsi-owner@vger.kernel.org List-Id: linux-scsi@vger.kernel.org To: Alasdair G Kergon Cc: Mike Anderson , Levy_Jerome , device-mapper development , "linux-scsi@vger.kernel.org" , asson_ronald , Mike Christie On Fri, 2008-11-14 at 19:34 +0000, Alasdair G Kergon wrote: > On Fri, Nov 14, 2008 at 11:08:48AM -0800, Chandra Seetharaman wrote: > > No, I "replaced" the "per-group" pg_init with "per-path" init. > > Indeed, but I'm pointing out that the per-group initialisation was > originally added for EMC and arguing that per-group initialisation > and per-path initialisation are independent conceptually and the > code may need to support both: adding one to deal with the problem > reported here need not necessitate removing the other. It was the case earlier. But Ed changed it (to send a mode select only when needed) before I moved the emc code to be under SCSI Hardware Handler. Later Hannes made it still better. IOW, The EMC code in SCSI hardware handler is smart to find out if the trespass/mode_select command need to be sent down the wire (they first do a inquiry and if the state is "OWNED", they just return). Hannes, MikeC, correct me if I am wrong. > > Alasdair