From mboxrd@z Thu Jan 1 00:00:00 1970 From: Hannes Reinecke Subject: Re: [PATCH] Add VPD support to aacraid Date: Fri, 26 Jan 2007 09:04:46 +0100 Message-ID: <45B9B61E.7040000@suse.de> References: Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: Received: from mail.suse.de ([195.135.220.2]:51049 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1030812AbXAZIEw (ORCPT ); Fri, 26 Jan 2007 03:04:52 -0500 In-Reply-To: Sender: linux-scsi-owner@vger.kernel.org List-Id: linux-scsi@vger.kernel.org To: "Salyzyn, Mark" Cc: SCSI Mailing List , Mark Haverkamp Salyzyn, Mark wrote: > Hannes, I am working the firmware and management software folks to fi= nd out how > to mine for this information. In your patch, the controller serial number may be > helpful, but not necessarily compliant? > Well, the information in page 0x80 is 'vendor specific'. So anything we put in there is compliant :-) > Besides persistent device id, what else is gained? The controller ens= ures persistent > device id for the arrays through the meta-data, only migrating if it happens to be a > foreign (from another controller) array that collides with a native array at the same > ID. Plug the constituent drives into totally different IDs in the SAS infrastructure, > the ID remains the same as presented by the controller. Plug those drives into another > controller, and if not taken by an existing array, the ID will again remain the same. > Yes, that's what I thought would happen. Main reason for adding page 0x80 support is to get it to work with the current persistent device ID setup from udev. There we're using the scsi_id program which doesn't return a serial number if neither page 0x83 nor page 0x80 are supported= =2E So just hacking them into the driver was the easiest way to get it fixe= d. And there is actually a second reason for adding page 0x80 support: If there were something like a build uuid for the array (either a prope= r uuid or maybe even the build date) we would be able to detect an array re-initialisation. Currently we won't be able to deal with this as the array will have the same ID, so we would try to mount a drive with a totally different content. That was actually what I was aiming for with that patch, but after two days of hacking I gave up and settled for the easy way out. I know that at least the array build date is somewhere, as the management software displays them :-). So it should be relatively easy to use that as the serial number. > If this is all of your concerns, adding the baggage to the driver > will be redundant. >=20 Actually, not quite. In not supporting EVPD page any compliant software must assume that there is not way of reliably distinguish between two drives from the same vendor/model. And, incidentally, it should be possible to hook in two controllers, an= d creating two arrays with the same name, right? So we _don't_ have a reliable way for doing so. And this is where EVPD page 0x80 support comes in. Cheers, Hannes --=20 Dr. Hannes Reinecke hare@suse.de SuSE Linux Products GmbH S390 & zSeries Maxfeldstra=DFe 5 +49 911 74053 688 90409 N=FCrnberg http://www.suse.de - 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