From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S266798AbUBMOIN (ORCPT ); Fri, 13 Feb 2004 09:08:13 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S266787AbUBMOIN (ORCPT ); Fri, 13 Feb 2004 09:08:13 -0500 Received: from mx1.redhat.com ([66.187.233.31]:23700 "EHLO mx1.redhat.com") by vger.kernel.org with ESMTP id S267002AbUBMOIJ (ORCPT ); Fri, 13 Feb 2004 09:08:09 -0500 Date: Thu, 12 Feb 2004 20:13:40 +0000 From: Joe Thornber To: Lars Marowsky-Bree Cc: Joe Thornber , Linux Mailing List Subject: Re: dm core patches Message-ID: <20040212201340.GB1898@reti> References: <20040210163548.GC27507@reti> <20040211101659.GF3427@marowsky-bree.de> <20040211103541.GW27507@reti> <20040212185145.GY21298@marowsky-bree.de> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20040212185145.GY21298@marowsky-bree.de> User-Agent: Mutt/1.5.5.1+cvs20040105i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Feb 12, 2004 at 07:51:45PM +0100, Lars Marowsky-Bree wrote: > I checked the archives, but I couldn't find anything really 'in flux'. > Your priority based approach seems just fine to me. > > What is still missing? This is really a killer feature for 2.6. Any help > I can offer? I think the main concern now is over the testing of paths. Sending an io down an inactive path can be very expensive for some hardware configurations. So I'm considering changing a couple of things: - Only ever send io to 1 priority group at a time (even test ios). To test the lower priority groups we'd have to periodically switch to them and use them for a bit for both test io and proper io. - For some hardware there are better ways of testing the path than sending the test io. Should the drivers expose a test function ? In the absence of this we'd fallback to the test io method. The other thing we need is to try and get the drivers to deferentiate between a media error and a path error, so that media errors get reported up quickly and don't cause false path failures. This is possibly an area that you could help with ? - Joe