From mboxrd@z Thu Jan 1 00:00:00 1970 From: =?ISO-8859-1?Q?Tor_Arne_Vestb=F8?= Subject: Creating RAID5 with four devices and end up with 5 (one removed and one spare). Why? Date: Mon, 3 Mar 2008 09:55:45 +0100 Message-ID: <47CBBD11.4020501@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset="US-ASCII"; format="flowed" Return-path: Content-Disposition: inline Sender: linux-raid-owner@vger.kernel.org To: linux-raid@vger.kernel.org List-Id: linux-raid.ids Hi! I'm trying to build a Linux RAID5 with four (4) 750GB disks, but not matter what I do I end up with mdadm listing five (5) devices and telling me that one of them is a spare, and another one is failed/removed. I've been googling and reading HOWTOs for a week now, but can't figure it out. Here's what I do: monstre:~/buildroot # mdadm --create /dev/md0 --level=5 --raid-devices=4 /dev/sd[cdef]1 mdadm: /dev/sdc1 appears to contain an ext2fs file system size=-2097251968K mtime=Wed Feb 27 00:26:57 2008 mdadm: /dev/sdc1 appears to be part of a raid array: level=raid5 devices=4 ctime=Tue Feb 26 20:47:24 2008 mdadm: /dev/sdd1 appears to be part of a raid array: level=raid5 devices=4 ctime=Tue Feb 26 20:47:24 2008 mdadm: /dev/sde1 appears to be part of a raid array: level=raid5 devices=4 ctime=Tue Feb 26 20:47:24 2008 mdadm: /dev/sdf1 appears to contain an ext2fs file system size=-1560381056K mtime=Wed Feb 27 00:26:57 2008 mdadm: /dev/sdf1 appears to be part of a raid array: level=raid5 devices=4 ctime=Tue Feb 26 20:47:24 2008 Continue creating array? y mdadm: array /dev/md0 started. monstre:~/buildroot # cat /proc/mdstat Personalities : [raid6] [raid5] [raid4] md0 : active(auto-read-only) raid5 sdf1[4](S) sde1[2] sdd1[1] sdc1[0] 2197715712 blocks level 5, 64k chunk, algorithm 2 [4/3] [UUU_] unused devices: monstre:~/buildroot # mdadm --detail /dev/md0 /dev/md0: Version : 00.90.03 Creation Time : Tue Feb 26 20:57:46 2008 Raid Level : raid5 Array Size : 2197715712 (2095.91 GiB 2250.46 GB) Used Dev Size : 732571904 (698.64 GiB 750.15 GB) Raid Devices : 4 Total Devices : 4 Preferred Minor : 0 Persistence : Superblock is persistent Update Time : Tue Feb 26 20:57:46 2008 State : clean, degraded Active Devices : 3 Working Devices : 4 Failed Devices : 0 Spare Devices : 1 Layout : left-symmetric Chunk Size : 64K UUID : 8b498455:0ab45ac1:ebf26e3f:56a9fc2f Events : 0.1 Number Major Minor RaidDevice State 0 8 33 0 active sync /dev/sdc1 1 8 49 1 active sync /dev/sdd1 2 8 65 2 active sync /dev/sde1 3 0 0 3 removed 4 8 81 - spare /dev/sdf1 monstre: # mdadm --examine /dev/sdd1 /dev/sdd1: Magic : a92b4efc Version : 00.90.00 UUID : a0186556:4ffb5a2a:822f8875:94ae7d2c Creation Time : Sun Mar 2 22:52:53 2008 Raid Level : raid5 Used Dev Size : 732571904 (698.64 GiB 750.15 GB) Array Size : 2197715712 (2095.91 GiB 2250.46 GB) Raid Devices : 4 Total Devices : 4 Preferred Minor : 0 Update Time : Sun Mar 2 22:59:54 2008 State : clean Active Devices : 3 Working Devices : 4 Failed Devices : 1 Spare Devices : 1 Checksum : 6b5e8442 - correct Events : 0.22 Layout : left-symmetric Chunk Size : 64K Number Major Minor RaidDevice State this 1 8 49 1 active sync /dev/sdd1 0 0 8 33 0 active sync /dev/sdc1 1 1 8 49 1 active sync /dev/sdd1 2 2 8 65 2 active sync /dev/sde1 3 3 0 0 3 faulty removed 4 4 8 81 4 spare /dev/sdf1 ------------------- So what i don't get is: 1. Why is mdadm --examine listing "3 3 0 0 3 faulty removed" and telling me I have a failed device? 2. Why is one of the actual disks (sdf) used as a spare, even though I didn't ask for it? Thanks for any tips or insights which may put me on the right track :) Tor Arne