From mboxrd@z Thu Jan 1 00:00:00 1970 From: Chandra Seetharaman Subject: RE: SCSI Hardware Handler and slow failover with large number of LUNS Date: Mon, 06 Apr 2009 10:47:06 -0700 Message-ID: <1239040026.25764.4.camel@chandra-ubuntu> References: <1238880636.11478.8.camel@chandra-ubuntu> <8F08A56613D77044BD153E2AC5DA0F8401A817E4@CORPUSMX40A.corp.emc.com> Reply-To: sekharan@linux.vnet.ibm.com, device-mapper development Mime-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <8F08A56613D77044BD153E2AC5DA0F8401A817E4@CORPUSMX40A.corp.emc.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: dm-devel-bounces@redhat.com Errors-To: dm-devel-bounces@redhat.com To: berthiaume_wayne@emc.com Cc: dm-devel@redhat.com, linux-scsi@vger.kernel.org, Babu.Moger@lsi.com List-Id: linux-scsi@vger.kernel.org On Mon, 2009-04-06 at 11:38 -0400, berthiaume_wayne@emc.com wrote: > Hi Chandra. > > We're currently testing 1024 LUNs across four paths with the > older handler but will be doing the same with the new handler later this Hi Wayne, What do you mean by "older" handler ? dm_emc ? > month. It sounds like I should move this up in the queue. > > Regards, > Wayne. > > -----Original Message----- > From: linux-scsi-owner@vger.kernel.org > [mailto:linux-scsi-owner@vger.kernel.org] On Behalf Of Chandra > Seetharaman > Sent: Saturday, April 04, 2009 5:31 PM > To: dm-devel; Linux SCSI Mailing list > Cc: Moger, Babu > Subject: SCSI Hardware Handler and slow failover with large number of > LUNS > > Hello All, > > During testing with the latest SCSI DH Handler on a rdac storage, Babu > found that the failover time with 100+ luns takes about 15 minutes, > which is not good. > > We found that the problem is due to the fact that we serialize activate > in dm on the work queue. > > We can solve the problem in rdac handler in 2 ways > 1. batch up the activates (mode_selects) and send few of them. > 2. Do mode selects in async mode. > > Just wondering if anybody had seen the same problem in other storages > (EMC, HP and Alua). > > Please share your experiences, so we can come up with a solution that > works for all hardware handlers. > > regards, > > chandra > > -- > 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 > > -- > 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