From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757578Ab1DHQNX (ORCPT ); Fri, 8 Apr 2011 12:13:23 -0400 Received: from kroah.org ([198.145.64.141]:48030 "EHLO coco.kroah.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752680Ab1DHQNV (ORCPT ); Fri, 8 Apr 2011 12:13:21 -0400 Date: Fri, 8 Apr 2011 09:12:12 -0700 From: Greg KH To: Nao Nishijima Cc: linux-kernel@vger.kernel.org, linux-scsi@vger.kernel.org, linux-hotplug@vger.kernel.org, Kay Sievers , James Bottomley , Jon Masters , 2nddept-manager@sdl.hitachi.co.jp Subject: Re: [PATCH 1/2] SCSI: Add a SCSI option for persistent device names in Kernel. Message-ID: <20110408161212.GA12111@kroah.com> References: <20110405124946.7969.66796.stgit@ltc233.sdl.hitachi.co.jp> <20110405161454.GB885@kroah.com> <4D9F16AD.2090408@hitachi.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <4D9F16AD.2090408@hitachi.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Apr 08, 2011 at 11:07:41PM +0900, Nao Nishijima wrote: > Hi, > > (2011/04/06 1:14), Greg KH wrote: > > On Tue, Apr 05, 2011 at 09:49:46PM +0900, Nao Nishijima wrote: > >> This patch series provides a SCSI option for persistent device > >> names in kernel. With this option, user can always assign a > >> same device name (e.g. sda) to a specific device according to > >> udev rules and device id. > >> > >> Issue: > >> Recently, kernel registers block devices in parallel. As a result, > >> different device names will be assigned at each boot time. This > >> will confuse file-system mounter, thus we usually use persistent > >> symbolic links provided by udev. However, dmesg and procfs outputs > >> show device names instead of the symbolic link names. This causes > >> a serious problem when managing multiple devices (e.g. on a > >> large-scale storage), because usually, device errors are output > >> with device names on dmesg. We also concern about some commands > >> which output device names, as well as kernel messages. > >> > >> Solution: > >> To assign a persistent device name, I create unnamed devices (not > >> a block device, but an intermediate device. users cannot read/write > >> this device). When scsi device driver finds a LU, the LU is registered > >> as an unnamed device and inform to udev. After udev finds the unnamed > >> device, udev assigns a persistent device name to a specific device > >> according to udev rules and registers it as a block device. Hence, > >> this is just a naming, not a renaming. > >> > >> Some users are satisfied with current udev solution. Therefore, my > >> proposal is implemented as an option. > >> > >> If using this option, add the following kernel parameter. > >> > >> scsi_mod.persistent_name=1 > >> > >> Also, if you want to assign a device name with sda, add the > >> following udev rules. > >> > >> SUBSYSTEM=="scsi_unnamed", ATTR{disk_id}=="xxx", PROGRAM="/bin/sh > >> -c 'echo -n sda > /sys/%p/disk_name'" > > > > Also, where is the "real" program you have created to properly name > > devices from userspace? You need that to properly test this patch, > > right? > > > > In the udev rule described above, notation “xxx” indicated by > ATTR(disk_id) is scsi id given by disk. Then, when udev finds this rule, > "/bin/sh -c 'echo -n sda> /sys/%p/disk_name'" indicated by PROGRAM is > operated using xxx (scsi id) if udev find the disk with scic id xxx. > Thus, persistent device name is assigned. > > I have tested this patch using the udev rule. and It works well. That's nice, but it's a "toy". What have you used to test this with 20000 scsi devices to properly work like it does today? Where is the program that will name them in a deterministic manner? We have that functionality today, you can't break it. thanks, greg k-h From mboxrd@z Thu Jan 1 00:00:00 1970 From: Greg KH Date: Fri, 08 Apr 2011 16:12:12 +0000 Subject: Re: [PATCH 1/2] SCSI: Add a SCSI option for persistent device names Message-Id: <20110408161212.GA12111@kroah.com> List-Id: References: <20110405124946.7969.66796.stgit@ltc233.sdl.hitachi.co.jp> <20110405161454.GB885@kroah.com> <4D9F16AD.2090408@hitachi.com> In-Reply-To: <4D9F16AD.2090408@hitachi.com> MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 8bit To: Nao Nishijima Cc: linux-kernel@vger.kernel.org, linux-scsi@vger.kernel.org, linux-hotplug@vger.kernel.org, Kay Sievers , James Bottomley , Jon Masters , 2nddept-manager@sdl.hitachi.co.jp On Fri, Apr 08, 2011 at 11:07:41PM +0900, Nao Nishijima wrote: > Hi, > > (2011/04/06 1:14), Greg KH wrote: > > On Tue, Apr 05, 2011 at 09:49:46PM +0900, Nao Nishijima wrote: > >> This patch series provides a SCSI option for persistent device > >> names in kernel. With this option, user can always assign a > >> same device name (e.g. sda) to a specific device according to > >> udev rules and device id. > >> > >> Issue: > >> Recently, kernel registers block devices in parallel. As a result, > >> different device names will be assigned at each boot time. This > >> will confuse file-system mounter, thus we usually use persistent > >> symbolic links provided by udev. However, dmesg and procfs outputs > >> show device names instead of the symbolic link names. This causes > >> a serious problem when managing multiple devices (e.g. on a > >> large-scale storage), because usually, device errors are output > >> with device names on dmesg. We also concern about some commands > >> which output device names, as well as kernel messages. > >> > >> Solution: > >> To assign a persistent device name, I create unnamed devices (not > >> a block device, but an intermediate device. users cannot read/write > >> this device). When scsi device driver finds a LU, the LU is registered > >> as an unnamed device and inform to udev. After udev finds the unnamed > >> device, udev assigns a persistent device name to a specific device > >> according to udev rules and registers it as a block device. Hence, > >> this is just a naming, not a renaming. > >> > >> Some users are satisfied with current udev solution. Therefore, my > >> proposal is implemented as an option. > >> > >> If using this option, add the following kernel parameter. > >> > >> scsi_mod.persistent_name=1 > >> > >> Also, if you want to assign a device name with sda, add the > >> following udev rules. > >> > >> SUBSYSTEM="scsi_unnamed", ATTR{disk_id}="xxx", PROGRAM="/bin/sh > >> -c 'echo -n sda > /sys/%p/disk_name'" > > > > Also, where is the "real" program you have created to properly name > > devices from userspace? You need that to properly test this patch, > > right? > > > > In the udev rule described above, notation “xxx” indicated by > ATTR(disk_id) is scsi id given by disk. Then, when udev finds this rule, > "/bin/sh -c 'echo -n sda> /sys/%p/disk_name'" indicated by PROGRAM is > operated using xxx (scsi id) if udev find the disk with scic id xxx. > Thus, persistent device name is assigned. > > I have tested this patch using the udev rule. and It works well. That's nice, but it's a "toy". What have you used to test this with 20000 scsi devices to properly work like it does today? Where is the program that will name them in a deterministic manner? We have that functionality today, you can't break it. thanks, greg k-h