From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753536AbdK3QpD (ORCPT ); Thu, 30 Nov 2017 11:45:03 -0500 Received: from mail-qk0-f193.google.com ([209.85.220.193]:38759 "EHLO mail-qk0-f193.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753376AbdK3QpA (ORCPT ); Thu, 30 Nov 2017 11:45:00 -0500 X-Google-Smtp-Source: AGs4zMYHLknXthNH/4g6nMsfVB2btDPoHzanIaRr9MP+3/QyAAAsCrUWJjk1XyS3qbcpHttTSA16bQ== Subject: Re: [PATCH v2] nvme-fc: don't require user to enter host_traddr To: Johannes Thumshirn , Christoph Hellwig Cc: Hannes Reinecke , Linux Kernel Mailinglist , Sagi Grimberg , Keith Busch , Linux NVMe Mailinglist , "Ewan D . Milne" References: <20171130151210.8168-1-jthumshirn@suse.de> From: James Smart Message-ID: Date: Thu, 30 Nov 2017 08:44:56 -0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:52.0) Gecko/20100101 Thunderbird/52.4.0 MIME-Version: 1.0 In-Reply-To: <20171130151210.8168-1-jthumshirn@suse.de> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Content-Language: en-US Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 11/30/2017 7:12 AM, Johannes Thumshirn wrote: > One major usability difference between NVMf RDMA and FC is resolving > the default host transport address in RDMA. This is perfectly doable > in FC as well, as we already have all possible lport <-> rport > combinations pre-populated so we can pick the first lport that has a > connection to our desired rport per default or optionally use the user > supplied lport if we have one. > > Signed-off-by: Johannes Thumshirn > Cc: James Smart This is unnecessary and can create weird configurations. It assumes connections are manually created. The weirdness is: a) an admin has to know there are multiple paths in order to connect them and be intelligent on how to get the complex name strings and try to know what connections are already in existence;  b) if a users has a connectivity loss beyond dev_loss_tmo or ctlr_loss_tmo such that the controller is terminated, they must manually issue the connec commands again; and c) those un-knowledgeable users will unknowingly find that their multiple paths aren't connected and the system will gang up on the host adapter detected on the system with connectivity. All things unexpected and not what occurs with FC and SCSI and which will result in system support calls. If the system uses the FC auto-connect scripts things will be properly connected across all paths connected to the subsystem - automatically, including resume after an extended connectivity loss - and the system will behave just like FC does with SCSI. I see no reason to add this patch.  Please move away from manual configuration. -- james From mboxrd@z Thu Jan 1 00:00:00 1970 From: james.smart@broadcom.com (James Smart) Date: Thu, 30 Nov 2017 08:44:56 -0800 Subject: [PATCH v2] nvme-fc: don't require user to enter host_traddr In-Reply-To: <20171130151210.8168-1-jthumshirn@suse.de> References: <20171130151210.8168-1-jthumshirn@suse.de> Message-ID: On 11/30/2017 7:12 AM, Johannes Thumshirn wrote: > One major usability difference between NVMf RDMA and FC is resolving > the default host transport address in RDMA. This is perfectly doable > in FC as well, as we already have all possible lport <-> rport > combinations pre-populated so we can pick the first lport that has a > connection to our desired rport per default or optionally use the user > supplied lport if we have one. > > Signed-off-by: Johannes Thumshirn > Cc: James Smart This is unnecessary and can create weird configurations. It assumes connections are manually created. The weirdness is: a) an admin has to know there are multiple paths in order to connect them and be intelligent on how to get the complex name strings and try to know what connections are already in existence;? b) if a users has a connectivity loss beyond dev_loss_tmo or ctlr_loss_tmo such that the controller is terminated, they must manually issue the connec commands again; and c) those un-knowledgeable users will unknowingly find that their multiple paths aren't connected and the system will gang up on the host adapter detected on the system with connectivity. All things unexpected and not what occurs with FC and SCSI and which will result in system support calls. If the system uses the FC auto-connect scripts things will be properly connected across all paths connected to the subsystem - automatically, including resume after an extended connectivity loss - and the system will behave just like FC does with SCSI. I see no reason to add this patch.? Please move away from manual configuration. -- james