From mboxrd@z Thu Jan 1 00:00:00 1970 From: Benjamin ESTRABAUD Subject: mdadm --fail requires writeable drive. Date: Wed, 13 Nov 2013 12:17:21 +0000 Message-ID: <52836DD1.8080605@mpstor.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: Sender: linux-raid-owner@vger.kernel.org To: Linux-RAID List-Id: linux-raid.ids Hi, I noticed that mdadm --fail will only work if a disk is present and is writeable. mdadm's Manage.c seems to first make sure the drive can be "stat"ed before proceeding (which will fail if the drive is gone), and then seemingly try to write "Faulty" to the drive's superblock as well as notifying MD of the drive failure. However, in many cases, a drive must be set faulty because it has gone offline. MD will do a very good job to set the drive faulty itself, provided that IOs are running on the array. If no IOs are running on the array, removing a drive and then trying to set it as failed will not work. Trying to "-r" the drive will also fail since the drive is not yet marked as failed, so deemed still in use. Looking through the code it seemed to me that MD could be told to fail a drive even if that drive was no longer present (the /dev/sdX device node file still is in this case), in the same way as remove works. Would that be possible? Am I missing something here? Thanks in advance for your help. Regards, Ben - MPSTOR