From mboxrd@z Thu Jan 1 00:00:00 1970 From: Bart Van Assche Subject: Re: [PATCH] scsi_dh_alua: Re-enable STPG for unavailable ports Date: Fri, 22 Jun 2012 18:50:20 +0000 Message-ID: <4FE4BE6C.1080608@acm.org> References: <4FE431A2.2050500@acm.org> <77471C95FAFD844C8CA02DD4F4C5FE2B07E504FD@SACEXCMBX02-PRD.hq.netapp.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Return-path: Received: from relay04ant.iops.be ([212.53.5.219]:39984 "EHLO relay04ant.iops.be" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758391Ab2FVSuY (ORCPT ); Fri, 22 Jun 2012 14:50:24 -0400 In-Reply-To: <77471C95FAFD844C8CA02DD4F4C5FE2B07E504FD@SACEXCMBX02-PRD.hq.netapp.com> Sender: linux-scsi-owner@vger.kernel.org List-Id: linux-scsi@vger.kernel.org To: "Moger, Babu" Cc: linux-scsi , Hannes Reinecke On 06/22/12 17:52, Moger, Babu wrote: > One concern, the spec also says.. > ============================== > The unavailable target port asymmetric access state is > intended for situations when the target port accessibility to a logical unit may be severely restricted due to SCSI > target device limitations (e.g., hardware errors). Therefore it may not be possible to transition from this state to > either the active/optimized, active/non-optimized or standby states. > ===================================================== > > What happens if we cannot transition to active/optimized, active/non-optimized or standby states. > Are we going to loop forever? From kernel side it looks ok. We are going mark the path as failed. > It depends on what the path checker from multipath is going to do. Do you have any idea about it? Good question. I'm not a multipath expert, but as far as I understand the multipath user space software if activating a path fails after some delay multipathd tries again to find a usable I/O path. Bart.