From mboxrd@z Thu Jan 1 00:00:00 1970 From: James Bottomley Subject: Re: Is there a grand plan for FC failover? Date: 29 Jan 2004 11:00:58 -0500 Sender: linux-scsi-owner@vger.kernel.org Message-ID: <1075392058.2381.44.camel@mulgrave> References: <401521A7.5030808@thekelleys.org.uk> <1075131446.2290.29.camel@mulgrave> <20040128100236.D11527@vienna.EGENERA.COM> <1075309052.2254.6.camel@mulgrave> <20040128130040.E11527@vienna.EGENERA.COM> <401839A8.307@us.ibm.com> <20040129102430.G11527@vienna.EGENERA.COM> Mime-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 7bit Return-path: Received: from stat1.steeleye.com ([65.114.3.130]:44230 "EHLO hancock.sc.steeleye.com") by vger.kernel.org with ESMTP id S266021AbUA2QBu (ORCPT ); Thu, 29 Jan 2004 11:01:50 -0500 In-Reply-To: <20040129102430.G11527@vienna.EGENERA.COM> List-Id: linux-scsi@vger.kernel.org To: "Philip R. Auld" Cc: Mike Christie , Simon Kelley , SCSI Mailing List On Thu, 2004-01-29 at 10:24, Philip R. Auld wrote: > I think the place to do load balancing would be below the block queue so that > the IOs are coalesced. IMO, until you've merged the individual block requests > you can't make a good decision about how to balance the load. Yes, that's what I think too, so the elevator should go above dm, with a vestigial elevator between dm and sd simply for SCSI to use in queuing. Unfortunately, the way it works today is that the elevator is between dm and sd. I know people are thinking about how to change this, but I'm not sure how far anyone's got. James