From mboxrd@z Thu Jan 1 00:00:00 1970 From: Hannes Reinecke Subject: Re: Designing a new prio_callout Date: Mon, 30 Jul 2007 08:31:01 +0200 Message-ID: <46AD85A5.1060609@suse.de> References: <46A735E1.4070206@suse.de> Reply-To: device-mapper development Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Return-path: In-Reply-To: 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 Ethan John wrote: > Thanks for the heads-up about ALUA. We're looking into it. >=20 > What is the purpose of the custom mpio_prio_* applications that ship > with open-iscsi if not to handle multipathing? >=20 It is. mpath_prio_* are the priority callouts for multipathing. They determine the layout of the multipath map. Theory is that mpath_prio_* will return the priority for a given path in relation to the entire multipath layout. If used with 'group_by_prio' all paths with the same priority will be grouped into one multipath group, and the group with the highest priority will become active. When all paths in a group fail, the group with the next highest priority will become active. Additionally some failover command (as determined by the hardware handler) may be send to the target. Cheers, Hannes --=20 Dr. Hannes Reinecke zSeries & Storage hare@suse.de +49 911 74053 688 SUSE LINUX Products GmbH, Maxfeldstr. 5, 90409 N=FCrnberg GF: Markus Rex, HRB 16746 (AG N=FCrnberg)