From mboxrd@z Thu Jan 1 00:00:00 1970 From: Christophe Varoqui Subject: Re: [dm-devel] Read-Only devices, multipath and more Date: Tue, 20 May 2008 23:09:49 +0200 Message-ID: <1211317789.31536.9.camel@plop> References: <1210966544.12901.51.camel@plop> <20080520144807.GC10723@agk.fab.redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: Received: from smtp7-g19.free.fr ([212.27.42.64]:39072 "EHLO smtp7-g19.free.fr" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758895AbYETVJg (ORCPT ); Tue, 20 May 2008 17:09:36 -0400 In-Reply-To: <20080520144807.GC10723@agk.fab.redhat.com> Sender: linux-scsi-owner@vger.kernel.org List-Id: linux-scsi@vger.kernel.org To: Alasdair G Kergon Cc: device-mapper development , linux-scsi@vger.kernel.org Le mardi 20 mai 2008 =C3=A0 15:48 +0100, Alasdair G Kergon a =C3=A9crit= : > On Fri, May 16, 2008 at 09:35:44PM +0200, christophe varoqui wrote: > > fact: device-mapper refuse to load a RW multipath table on these pa= ths > > (ie without libdevmapper:set_task_set_ro()) > > question: should change this behaviour to allow to load a RW multip= ath > > table on these paths and let the IO be failed by the storage hardwa= re ? >=20 > Yes. But relax this *only* for multipath targets, where the whole id= ea > is to "hide" path problems from the layer above. =EF=BB=BF =46air enough. > It would not make sense=20 > in my view to do this for other DM targets. > =20 During my testing I remember seeing a RW linear map loaded over a RO multipath map (through a genuine vgchange -ay, the PV being the multipath). > > Alasdair proposed to add more explicit table loading ioctl return c= ode > > when the failure is due to this ready-only paths issue (E_ROFS for > > example). >=20 > I think this should be done too (for non-multipath and other errors). >=20 Right, I'm about the publish a changeset for supporting the whole RO notion in the multipath-tools : 1/ printing the RO/RW information 2/ fallbacking to RO when RW loading fails 3/ new flag to force map reloading, which takes care of the RO->RW promotion and RW->RO demotion scenarii I'll adapt 2/ to your new return codes when available. Thanks for caring, cvaroqui -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" i= n the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html