From mboxrd@z Thu Jan 1 00:00:00 1970 From: Chandra Seetharaman Subject: Re: [dm-devel] mechanism for multipath to pass information to hardware handler Date: Fri, 26 Jun 2009 12:45:09 -0700 Message-ID: <1246045509.14164.33.camel@chandra-ubuntu> References: <1245863681.8709.135.camel@eddie-laptop> <1246043447.3925.64.camel@mulgrave.site> Reply-To: sekharan@linux.vnet.ibm.com Mime-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 7bit Return-path: Received: from e34.co.us.ibm.com ([32.97.110.152]:60880 "EHLO e34.co.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757372AbZFZTmv (ORCPT ); Fri, 26 Jun 2009 15:42:51 -0400 Received: from d03relay02.boulder.ibm.com (d03relay02.boulder.ibm.com [9.17.195.227]) by e34.co.us.ibm.com (8.13.1/8.13.1) with ESMTP id n5QJde5T000691 for ; Fri, 26 Jun 2009 13:39:40 -0600 Received: from d03av02.boulder.ibm.com (d03av02.boulder.ibm.com [9.17.195.168]) by d03relay02.boulder.ibm.com (8.13.8/8.13.8/NCO v9.2) with ESMTP id n5QJgqRD239550 for ; Fri, 26 Jun 2009 13:42:52 -0600 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 n5QJgpZF024595 for ; Fri, 26 Jun 2009 13:42:52 -0600 In-Reply-To: <1246043447.3925.64.camel@mulgrave.site> Sender: linux-scsi-owner@vger.kernel.org List-Id: linux-scsi@vger.kernel.org To: James Bottomley Cc: device-mapper development , SCSI development list , "Rafael J. Wysocki" , Mike Christie , Edward Goggin , "Benoit, Arthur" , asson_ronald , berthiaume_wayne Yes, Mike Christie and I were aware of this and it was one of the issue we were trying to resolve before we pushed scsi_dh interface upstream. (It is little complicated as we need the parameters to be set per vendor-product tuple). The original code I ported to scsi_dh interface was from Ed Goggin(who was working for EMC then). IIRC, he was also aware of this issue. When we pushed scsi_dh interface, we did get few of the EMC folks (on Cc) to review/test the code and they did, and this issue was not seen as a problem. We wanted to get back to that issue sometime later, got busy with other things, and it disappeared from my list of things-to-do as the regression was not seen as an issue (till now :)... I will get back to it. chandra On Fri, 2009-06-26 at 14:10 -0500, James Bottomley wrote: > On Wed, 2009-06-24 at 13:14 -0400, Eddie Williams wrote: > > I notice in scsi_dh_emc.c that there is a comment: > > > > TODO: need some interface so we can set trespass values > > > > I don't see where any such interface has been developed or even any > > discussion on the different mailing lists to create such an interface. > > Did I miss something? > > > > As it stands now there is no way that I can see to have the emc hardware > > handler support the "honor trespass" feature short of recompiling the > > module forcing the flag to be set. This leaves a feature that worked in > > earlier versions of multipath not working now. > > OK so as I understand it that means that the line > > hardware handler "1 emc 0 1" > > now fails to function correctly because dm-emc no longer exists. That > makes this a functionality regression from 2.6.26 because of this > commit: > > > commit cb520223d7f22c5386aff27a5856a66e2c32aaac > Author: Chandra Seetharaman > Date: Thu May 1 14:50:34 2008 -0700 > > [SCSI] scsi_dh: Remove hardware handlers from dm > > This patch removes the 3 hardware handlers that currently exist > under dm as the functionality is moved to SCSI layer in the earlier > patches. > > Because we haven't actually moved all the functionality. > > James > > >