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 17:03:36 -0700 Message-ID: <1246061016.14164.45.camel@chandra-ubuntu> References: <1245863681.8709.135.camel@eddie-laptop> <1246043447.3925.64.camel@mulgrave.site> <1246045509.14164.33.camel@chandra-ubuntu> <1246046154.3925.80.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 e35.co.us.ibm.com ([32.97.110.153]:45669 "EHLO e35.co.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752209AbZF0ABQ (ORCPT ); Fri, 26 Jun 2009 20:01:16 -0400 Received: from d03relay02.boulder.ibm.com (d03relay02.boulder.ibm.com [9.17.195.227]) by e35.co.us.ibm.com (8.13.1/8.13.1) with ESMTP id n5QNrr7w000606 for ; Fri, 26 Jun 2009 17:53:53 -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 n5R01Ivs243566 for ; Fri, 26 Jun 2009 18:01:18 -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 n5R01ItB012480 for ; Fri, 26 Jun 2009 18:01:18 -0600 In-Reply-To: <1246046154.3925.80.camel@mulgrave.site> Sender: linux-scsi-owner@vger.kernel.org List-Id: linux-scsi@vger.kernel.org To: device-mapper development Cc: SCSI development list , asson_ronald , "Rafael J. Wysocki" , Mike Christie , "Benoit, Arthur" On Fri, 2009-06-26 at 14:55 -0500, James Bottomley wrote: > On Fri, 2009-06-26 at 12:45 -0700, Chandra Seetharaman wrote: > > 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. > > One way around this might simply be to make the device_handlers create a > sysfs interface for additional parameters. Then the multipath command Yes, having a per device interface is one of the options we considered. Once we have that defined we can either use sysfs or a scsi_dh_8() API to achieve the same. But we wanted to have it per vendor-product instead of per device, I don't recall the problems associated with it. Mike(C), do you recall ? > can feed them (or in a pinch, users relying on the features can pass > them in manually). Right at the moment having no possible work around > does appear to be an issue. I will try to roll up a patch soon. > > James > > > -- > dm-devel mailing list > dm-devel@redhat.com > https://www.redhat.com/mailman/listinfo/dm-devel