From mboxrd@z Thu Jan 1 00:00:00 1970 From: Hannes Reinecke Subject: Re: Can DM-Multipath work on non-SCSI block device Date: Thu, 14 Mar 2013 11:44:03 +0100 Message-ID: <5141A9F3.90801@suse.de> References: <51419874.50308@suse.de> <5141A948.3010403@redhat.com> Reply-To: device-mapper development Mime-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1"; Format="flowed" Content-Transfer-Encoding: quoted-printable Return-path: In-Reply-To: <5141A948.3010403@redhat.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: dm-devel-bounces@redhat.com Errors-To: dm-devel-bounces@redhat.com To: "Bryn M. Reeves" Cc: device-mapper development List-Id: dm-devel.ids On 03/14/2013 11:41 AM, Bryn M. Reeves wrote: > On 03/14/2013 09:29 AM, Hannes Reinecke wrote: >> On 03/14/2013 08:58 AM, Ahmed Al-Mehdi wrote: >>> Hello, >>> >>> I read the documentation on the dm-multipath home page: >>> htttp://christophe.varoqui.free.fr/refbook.html >>> , that describes >>> how the userspace multipath tool detects and maps (scsi) devices. >>> However, would like to confirm, does the dm-multipath utilty only >>> work with SCSI devices. Is there any option to make it (or fake it) >>> to work with non-SCSI block device. >>> >> If you can figure out a way on how to get a unique _disk_ id without >> SCSI, sure. > > E.g. cciss devices are supported using the cciss_id program - that's > a good example of a very "non-scsi" device type working with multipath. > > As well as the WWID problem you'll need to come up with some scheme > for faking unique HCIL values for the devices since multipath > userspace cares about that. The cciss approach is to force lun and > channel to '0' for all devices and to use the CCISS controller (cN) > and disk (dN) values for the host and id (aka target) values. > > See the functions in discovery.c with a cciss_ prefix for more > examples. > Or the dasd variant of those. However, the HCIL variable is mostly cosmetic. The disk id is the true issue; without it you cannot do multipathing. Cheers, Hannes -- = Dr. Hannes Reinecke zSeries & Storage hare@suse.de +49 911 74053 688 SUSE LINUX Products GmbH, Maxfeldstr. 5, 90409 N=FCrnberg GF: J. Hawn, J. Guild, F. Imend=F6rffer, HRB 16746 (AG N=FCrnberg)