From mboxrd@z Thu Jan 1 00:00:00 1970 From: Chandra Seetharaman Subject: Re: [PATCH 1/3] scsi_dh: Add modalias support for SCSI targets Date: Tue, 07 Apr 2009 16:41:50 -0700 Message-ID: <1239147710.14988.14.camel@chandra-ubuntu> References: <20090318013615.26548.36303.sendpatchset@chandra-ubuntu> <20090318013621.26548.10529.sendpatchset@chandra-ubuntu> <1237403902.14147.25.camel@chandra-ubuntu> <1237488880.26341.15.camel@chandra-ubuntu> <49C3DF49.8050408@redhat.com> <1237846429.14853.6.camel@chandra-ubuntu> <1238798590.20924.0.camel@chandra-ubuntu> <1239137973.29492.12.camel@mulgrave> Reply-To: sekharan@linux.vnet.ibm.com Mime-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 7bit Return-path: Received: from e35.co.us.ibm.com ([32.97.110.153]:58459 "EHLO e35.co.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750999AbZDGXlk (ORCPT ); Tue, 7 Apr 2009 19:41:40 -0400 Received: from d03relay04.boulder.ibm.com (d03relay04.boulder.ibm.com [9.17.195.106]) by e35.co.us.ibm.com (8.13.1/8.13.1) with ESMTP id n37Nae3j004663 for ; Tue, 7 Apr 2009 17:36:40 -0600 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 v9.2) with ESMTP id n37Nfd1U228972 for ; Tue, 7 Apr 2009 17:41:39 -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 n37Nfcgi011150 for ; Tue, 7 Apr 2009 17:41:39 -0600 In-Reply-To: <1239137973.29492.12.camel@mulgrave> Sender: linux-scsi-owner@vger.kernel.org List-Id: linux-scsi@vger.kernel.org To: James Bottomley Cc: Kay Sievers , linux-scsi@vger.kernel.org, michaelc@cs.wisc.edu, Peter Jones Thanks for the response James. On Tue, 2009-04-07 at 20:59 +0000, James Bottomley wrote: > On Fri, 2009-04-03 at 15:43 -0700, Chandra Seetharaman wrote: > > Hi James, > > > > Do you still have any concerns (after Peter's response) ? > > Yes, the basic concerns still remain: > > 1. You're forcing autoload now even if the user isn't running > dm ... this is going to cause problems with non-dm based path > handlers As I mentioned in an earlier email, the purpose of moving the device handler to SCSI layer from dm layer was to make sure that the device in-differences are taken care of. For example, the lsi rdac storage is active/passive and we do want the SCSI layer to handle appropriately so that the I/O is not tried repeatedly in the passive path. With the device handler in SCSI layer we were able to handle it properly, thereby reducing the boot time nicely. So, for all practical purposes these device handlers serve a purpose by themselves, even without dm-multipath ever needing to use it. What dm-multipath does by way of calling scsi_dh_activate can also be done by the interface Hannes added to the sysfs. > 2. autoloading in this fashion is essentially trying to work around > a problem in the initrd tools. The kernel isn't the right place > to implement the fix. I defer this question to Peter :) > > The risks of this approach seem very high, and the rewards pretty small. > > James > > > -- > To unsubscribe from this list: send the line "unsubscribe linux-scsi" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html