I am new to linux world. I had 4 disks passed down to me and was told that they were RAID 5 configuration. Due to historical reason, I have to figure out the details and also extract the data from there. I tried to boot up from Ubuntu Live CD and firstly, I tried sudo fdisk -l /dev/sdx (for disk sda, sdb, sdc and sdd) and get Device Boot Start End Blocks Id System /dev/sdx1 1 48 385528+ 83 Linux /dev/sdx2 49 65 136552+ 82 Linux swap / Solaris /dev/sdx3 66 60772 487620946 83 Linux /dev/sdx4 60772 60801 240974 83 Linux I then read about in forum and finally after much struggle, I tried to reform the raid volume by : sudo mdadm --create /dev/md3 --assume-clean --level=5 --verbose --raid-device=4 /dev/sdd3 /dev/sdc3 /dev/sdb3 /dev/sda3 I have to make some assumption on the disk order and guess most probably the data should be in /dev/sdx3 I got the prompt as : mdadm: layout defaults to left-symmetric mdadm: chunk size defaults to 64K mdadm: /dev/sdd3 appears to be part of a raid array: level=raid5 devices=4 ctime=Tue Mar 3 06:48:25 2009 mdadm: /dev/sdc3 appears to be part of a raid array: level=raid5 devices=4 ctime=Tue Mar 3 06:48:25 2009 mdadm: /dev/sdb3 appears to be part of a raid array: level=raid5 devices=4 ctime=Tue Mar 3 06:48:25 2009 mdadm: /dev/sda3 appears to be part of a raid array: level=raid5 devices=4 ctime=Tue Mar 3 06:48:25 2009 mdadm: size set to 487620864K Continue creating array? y mdadm: array /dev/md3 started. So far so good. I then do cat /proc/mdstat and get md3 : active raid5 sda3[3] sdb3[2] sdc3[1] sdd3[0] 1462862592 blocks level 5, 64k chunk, algorithm 2 [4/4] [UUUU] so I thought I should be on the way to get the data. I do a mount su do mount /dev/md3 /mnt I have the error mount: /dev/md3: can't read superblock No matter how I tried the mount command, the error is persistent. I then do sudo mdadm --detail /dev/md3 Version : 00.90 Creation Time : Tue Mar 3 08:15:49 2009 Raid Level : raid5 Array Size : 1462862592 (1395.09 GiB 1497.97 GB) Used Dev Size : 487620864 (465.03 GiB 499.32 GB) Raid Devices : 4 Total Devices : 4 Preferred Minor : 3 Persistence : Superblock is persistent Update Time : Tue Mar 3 08:19:05 2009 State : clean Active Devices : 4 Working Devices : 4 Failed Devices : 0 Spare Devices : 0 Layout : left-symmetric Chunk Size : 64K UUID : 5430b403:a58267ca:e368bf24:bd0fce41 (local to host ubuntu) Events : 0.2 Number Major Minor RaidDevice State 0 8 51 0 active sync /dev/sdd3 1 8 35 1 active sync /dev/sdc3 2 8 19 2 active sync /dev/sdb3 3 8 3 3 active sync /dev/sda3 That look good though. I do sudo mdadm --examine /dev/md3 mdadm: No md superblock detected on /dev/md3. Any idea how I could mount the array ? So far and yet so close. Is the problem caused by wrong disk order ? If so, how do I find out the correct order ? Any help or feedback is appreciated
