From mboxrd@z Thu Jan 1 00:00:00 1970 From: Hannes Reinecke Subject: Re: [PATCH 18/23] scsi_dh_alua: Send TEST UNIT READY to poll for transitioning Date: Fri, 12 Feb 2016 08:12:59 +0100 Message-ID: <56BD85FB.7060907@suse.de> References: <1454942086-128704-1-git-send-email-hare@suse.de> <1454942086-128704-19-git-send-email-hare@suse.de> <1455222318.22112.330.camel@localhost.localdomain> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: Received: from mx2.suse.de ([195.135.220.15]:48988 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750773AbcBLHNC (ORCPT ); Fri, 12 Feb 2016 02:13:02 -0500 In-Reply-To: <1455222318.22112.330.camel@localhost.localdomain> Sender: linux-scsi-owner@vger.kernel.org List-Id: linux-scsi@vger.kernel.org To: emilne@redhat.com Cc: "Martin K. Petersen" , Christoph Hellwig , Bart van Assche , James Bottomley , linux-scsi@vger.kernel.org On 02/11/2016 09:25 PM, Ewan Milne wrote: > On Mon, 2016-02-08 at 15:34 +0100, Hannes Reinecke wrote: >> Sending a 'REPORT TARGET PORT GROUP' command is a costly operation, >> as the array has to gather information about all ports. >> So instead of using RTPG to poll for a status update when a port >> is in transitioning we should be sending a TEST UNIT READY, and >> wait for the sense code to report success. >=20 > Note that we may need to add a timeout on this somehow, I have > recently seen a bug report where an array stayed in the ALUA > transitioning state for an extremely long period of time. >=20 > That problem would occur with either the current or this new > ALUA code, the question is whether we want to handle it better. >=20 There already is provisioning in the code to set the port to STANDBY if the transitioning time is exceeded. Not that this code path is well tested, but it's there :-) Cheers, Hannes --=20 Dr. Hannes Reinecke Teamlead Storage & Networking hare@suse.de +49 911 74053 688 SUSE LINUX GmbH, Maxfeldstr. 5, 90409 N=C3=BCrnberg GF: F. Imend=C3=B6rffer, J. Smithard, J. Guild, D. Upmanyu, G. Norton HRB 21284 (AG N=C3=BCrnberg) -- 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