From mboxrd@z Thu Jan 1 00:00:00 1970 From: Luca Berra Subject: Re: dm-multipath has great throughput but we'd like more! Date: Thu, 18 May 2006 09:59:40 +0200 Message-ID: <20060518075940.GF26035@percy.comedia.it> References: <1147935929.27006.57.camel@baggage> <1147938254.27006.65.camel@baggage> Reply-To: device-mapper development Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Return-path: Content-Disposition: inline In-Reply-To: <1147938254.27006.65.camel@baggage> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: dm-devel-bounces@redhat.com Errors-To: dm-devel-bounces@redhat.com To: device-mapper development List-Id: dm-devel.ids On Thu, May 18, 2006 at 08:44:14AM +0100, Bob Gautier wrote: >The card is a 64-bit PCI-X, so I don't think the bus is the bottleneck, >and anyway the vendor specifies a maximum throughput of 200Mbyte/s per >card. > >The disk array does not appear to be the bottleneck because we get >200Mbyte/s when we use *two* HBAs in load-balanced mode. > >The question is really about why we only see O(100Mbyte/s) with one HBA >when we can achieve O(200MByte/s) with two cards, given that one card >should be able to achieve that throughput. > >I don't think the method of producing the traffic (bonnie++ or something >else) should be relevant but if it were that would be very interesting >for the benchmark authors! > >The storage is an HDS 9980 (I think?) i am not an expert with Hitachi storages, anyway does each hba map to a different controller on the storage? do you have some statistics on disk usage from the storage side? L. -- Luca Berra -- bluca@comedia.it Communication Media & Services S.r.l. /"\ \ / ASCII RIBBON CAMPAIGN X AGAINST HTML MAIL / \