From mboxrd@z Thu Jan 1 00:00:00 1970 From: Nat Makarevitch Subject: Determining which spindle is out of order Date: Wed, 3 Nov 2010 14:13:25 +0000 (UTC) Message-ID: Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Return-path: Sender: linux-raid-owner@vger.kernel.org To: linux-raid@vger.kernel.org List-Id: linux-raid.ids Hi, After a spindle (physical hard disk, a "drive") failure in a "md" RAID array, how can we know which spindle must be replaced? We want to avoid extracting a working spindle by mistakenly thinking it is the faulty one... To solve this problem we put on each spindle a physical label (a tag, not a partition/disk label) showing its device name (sda, sdb...). To do so: on an otherwise unused system and sane RAID array we ran "dd" for each each spindle (individual device) in order to read on it, lighting up its LED. Then we simulated a crash by physically removing two spindles. Upon reboot the devices names changed (?!) and our labels weren't right anymore albeit we are pretty sure they were. Context: raid10, 10 spindles (8 active + 2 spare), layout : near=1, offset=3. On the integrated controller + a LSI MPT on-board controller.