From mboxrd@z Thu Jan 1 00:00:00 1970 From: Greg KH Date: Tue, 05 Apr 2011 16:14:54 +0000 Subject: Re: [PATCH 1/2] SCSI: Add a SCSI option for persistent device names Message-Id: <20110405161454.GB885@kroah.com> List-Id: References: <20110405124946.7969.66796.stgit@ltc233.sdl.hitachi.co.jp> In-Reply-To: <20110405124946.7969.66796.stgit@ltc233.sdl.hitachi.co.jp> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit 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 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? thanks, greg k-h