From mboxrd@z Thu Jan 1 00:00:00 1970 From: Hannes Reinecke Subject: Re: [PATCH 02/17] scsi_dh_alua: Disable ALUA handling for non-disk devices Date: Mon, 11 May 2015 12:25:51 +0200 Message-ID: <555083AF.1000605@suse.de> References: <1430743343-47174-1-git-send-email-hare@suse.de> <1430743343-47174-3-git-send-email-hare@suse.de> <20150511064643.GB30516@lst.de> Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: Received: from cantor2.suse.de ([195.135.220.15]:38270 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752713AbbEKKZw (ORCPT ); Mon, 11 May 2015 06:25:52 -0400 In-Reply-To: <20150511064643.GB30516@lst.de> Sender: linux-scsi-owner@vger.kernel.org List-Id: linux-scsi@vger.kernel.org To: Christoph Hellwig Cc: James Bottomley , linux-scsi@vger.kernel.org On 05/11/2015 08:46 AM, Christoph Hellwig wrote: > On Mon, May 04, 2015 at 02:42:08PM +0200, Hannes Reinecke wrote: >> Non-disk devices should be ignored when detecting >> ALUA capabilities. >=20 > Hmm. I don't think we should even attach the alua handler in this ca= se, > e.g. refine the check in scsi_dh_find_driver. But then again I don't > remember how the spec wording actually disallows this, and a quick gr= ep > of SPC-4 can't find anything either. Can you put a reference to the = spec > section that disallows attachment to non-disk devices into the code? >=20 The spec wording doesn't explicitly disallowing you from doing so (unless you're using referrals). But in realiter we're using the ALUA device handler only when multipathing is used, which in turn runs on disk devices only. So we can limit ourselves to disk devices, too. Everything else (like tapes or tape changers) will have to implement their own logic anyway; tape support in multipathing with or without ALUA is too horrible to contemplate ... >> + if (sdev->type !=3D TYPE_DISK && >> + sdev->type !=3D TYPE_RBC && >> + sdev->type !=3D TYPE_OSD) { >=20 > And does it really allow RBC (but not ZBC)? >=20 Thought so, but I'll have to cross-check. Maybe it's time to implement a 'scsi_is_disk_type()' macro... Cheers, Hannes --=20 Dr. Hannes Reinecke zSeries & Storage hare@suse.de +49 911 74053 688 SUSE LINUX GmbH, Maxfeldstr. 5, 90409 N=FCrnberg GF: F. Imend=F6rffer, J. Smithard, J. Guild, D. Upmanyu, G. Norton HRB 21284 (AG N=FCrnberg) -- 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