From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S264245AbUBPMRN (ORCPT ); Mon, 16 Feb 2004 07:17:13 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S264419AbUBPMRN (ORCPT ); Mon, 16 Feb 2004 07:17:13 -0500 Received: from p508155B0.dip.t-dialin.net ([80.129.85.176]:56193 "EHLO o.ww.redhat.com") by vger.kernel.org with ESMTP id S264245AbUBPMRL (ORCPT ); Mon, 16 Feb 2004 07:17:11 -0500 Date: Mon, 16 Feb 2004 13:17:09 +0100 From: Heinz Mauelshagen To: Joe Thornber Cc: Lars Marowsky-Bree , Linux Mailing List , axboe@suse.de Subject: Re: dm core patches Message-ID: <20040216121709.GA15372@redhat.com> Reply-To: mauelshagen@redhat.com References: <20040210163548.GC27507@reti> <20040211101659.GF3427@marowsky-bree.de> <20040211103541.GW27507@reti> <20040212185145.GY21298@marowsky-bree.de> <20040212201340.GB1898@reti> <20040213151213.GR21298@marowsky-bree.de> <20040213153936.GF15736@reti> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20040213153936.GF15736@reti> User-Agent: Mutt/1.4.1i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Feb 13, 2004 at 03:39:36PM +0000, Joe Thornber wrote: > On Fri, Feb 13, 2004 at 04:12:14PM +0100, Lars Marowsky-Bree wrote: > > On 2004-02-12T20:13:40, > > Joe Thornber said: > > > > > 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. > > > > You are missing the obvious answer: > > > > - Periodically checking paths is a user-space issue and doesn't belong > > into the kernel. User-space gets to handle this policy. > > Yes, that is obvious, I had wanted to do failback automatically. But > pushing it to userland does allow people to write hardware specific > tests. I'll try it and see what people think. Right, such policy belongs to userpsace it seems. The reason why I put it into the multipath target is to cover the case, where all paths are inoperational, the system is OOM _and_ the only chance to recover from that is the hope to unfail a path in order to release memory preasure. 'Sorry, userspace test handler can't run, your enterprise server is a pile of sh..' is not acceptable in case there's a path we could unfail IMO. Regards, Heinz -- The LVM Guy -- > > Thanks, > > - Joe > - > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/ *** Software bugs are stupid. Nevertheless it needs not so stupid people to solve them *** =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=- Heinz Mauelshagen Red Hat, Inc. Consulting Development Engineer Am Sonnenhang 11 56242 Marienrachdorf Germany Mauelshagen@RedHat.com +49 2626 141200 FAX 924446 =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-