Hi! I used a western digital mybookworld (SOHO NAS storage using Linux) as backup for my Linux box. Suddenly, the mybookworld does not boot up any more. So I opened the box, removed the hard disk and put the hard disk into an external USB HDD case, and connected it to my Linux box. [ 530.640301] usb 2-1: new high speed USB device using ehci_hcd and address 3 [ 530.797630] scsi7 : usb-storage 2-1:1.0 [ 531.794844] scsi 7:0:0:0: Direct-Access WDC WD75 00AAKS-00RBA0 PQ: 0 ANSI: 2 [ 531.796490] sd 7:0:0:0: Attached scsi generic sg3 type 0 [ 531.797966] sd 7:0:0:0: [sdc] 1465149168 512-byte logical blocks: (750 GB/698 GiB) [ 531.800317] sd 7:0:0:0: [sdc] Write Protect is off [ 531.800327] sd 7:0:0:0: [sdc] Mode Sense: 38 00 00 00 [ 531.800333] sd 7:0:0:0: [sdc] Assuming drive cache: write through [ 531.803821] sd 7:0:0:0: [sdc] Assuming drive cache: write through [ 531.803836] sdc: sdc1 sdc2 sdc3 sdc4 [ 531.815831] sd 7:0:0:0: [sdc] Assuming drive cache: write through [ 531.815842] sd 7:0:0:0: [sdc] Attached SCSI disk The dmesg output looks normal, but I was wondering why the hardisk was not mounted at all. And why there are 4 different partitions on it. fdisk showed the following: root@ubuntu:/home/ubuntu# fdisk /dev/sdc WARNING: DOS-compatible mode is deprecated. It's strongly recommended to switch off the mode (command 'c') and change display units to sectors (command 'u'). Command (m for help): p Disk /dev/sdc: 750.2 GB, 750156374016 bytes 255 heads, 63 sectors/track, 91201 cylinders Units = cylinders of 16065 * 512 = 8225280 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x00007c00 Device Boot Start End Blocks Id System /dev/sdc1 4 369 2939895 fd Linux raid autodetect /dev/sdc2 370 382 104422+ fd Linux raid autodetect /dev/sdc3 383 505 987997+ fd Linux raid autodetect /dev/sdc4 506 91201 728515620 fd Linux raid autodetect Oh no! Everything seems to be created as a mdadm software raid. Calling mdadm --examine with the different partitions seems to affirm that. I think the only partition I am interested in, is /dev/sdc4 (because it is the largest). But nevertheless I called mdadm --examine with every partition. root@ubuntu:/home/ubuntu# mdadm --examine /dev/sdc1 /dev/sdc1: Magic : a92b4efc Version : 00.90.00 UUID : 5626a2d8:070ad992:ef1c8d24:cd8e13e4 Creation Time : Wed Feb 20 00:57:49 2002 Raid Level : raid1 Used Dev Size : 2939776 (2.80 GiB 3.01 GB) Array Size : 2939776 (2.80 GiB 3.01 GB) Raid Devices : 2 Total Devices : 1 Preferred Minor : 1 Update Time : Sun Nov 21 11:05:27 2010 State : clean Active Devices : 1 Working Devices : 1 Failed Devices : 1 Spare Devices : 0 Checksum : 4c90bc55 - correct Events : 16682 Number Major Minor RaidDevice State this 0 8 1 0 active sync /dev/sda1 0 0 8 1 0 active sync /dev/sda1 1 1 0 0 1 faulty removed root@ubuntu:/home/ubuntu# mdadm --examine /dev/sdc2 /dev/sdc2: Magic : a92b4efc Version : 00.90.00 UUID : 9734b3ee:2d5af206:05fe3413:585f7f26 Creation Time : Wed Feb 20 00:57:54 2002 Raid Level : raid1 Used Dev Size : 104320 (101.89 MiB 106.82 MB) Array Size : 104320 (101.89 MiB 106.82 MB) Raid Devices : 2 Total Devices : 1 Preferred Minor : 2 Update Time : Wed Oct 27 20:19:08 2010 State : clean Active Devices : 1 Working Devices : 1 Failed Devices : 1 Spare Devices : 0 Checksum : 55560b40 - correct Events : 9884 Number Major Minor RaidDevice State this 0 8 2 0 active sync /dev/sda2 0 0 8 2 0 active sync /dev/sda2 1 1 0 0 1 faulty removed root@ubuntu:/home/ubuntu# mdadm --examine /dev/sdc3 /dev/sdc3: Magic : a92b4efc Version : 00.90.00 UUID : 08f30b4f:91cca15d:2332bfef:48e67824 Creation Time : Wed Feb 20 00:57:54 2002 Raid Level : raid1 Used Dev Size : 987904 (964.91 MiB 1011.61 MB) Array Size : 987904 (964.91 MiB 1011.61 MB) Raid Devices : 2 Total Devices : 1 Preferred Minor : 3 Update Time : Sun Nov 21 11:05:27 2010 State : clean Active Devices : 1 Working Devices : 1 Failed Devices : 1 Spare Devices : 0 Checksum : 39717874 - correct Events : 73678 Number Major Minor RaidDevice State this 0 8 3 0 active sync 0 0 8 3 0 active sync 1 1 0 0 1 faulty removed root@ubuntu:/home/ubuntu# mdadm --examine /dev/sdc4 /dev/sdc4: Magic : a92b4efc Version : 00.90.00 UUID : febb75ca:e9d1ce18:f14cc006:f759419a Creation Time : Wed Feb 20 00:57:55 2002 Raid Level : raid1 Used Dev Size : 728515520 (694.77 GiB 746.00 GB) Array Size : 728515520 (694.77 GiB 746.00 GB) Raid Devices : 2 Total Devices : 1 Preferred Minor : 4 Update Time : Sun Nov 21 11:05:27 2010 State : clean Active Devices : 1 Working Devices : 1 Failed Devices : 1 Spare Devices : 0 Checksum : 2f36a392 - correct Events : 519320 Number Major Minor RaidDevice State this 0 8 4 0 active sync 0 0 8 4 0 active sync 1 1 0 0 1 faulty removed If I read the output correctly everything was removed, because it was faulty. Is there ANY way to see the contents of the largest partition? Or seeing somehow which files are broken? I see that everything is raid1 which is only mirroring, so this should be a normal partition. I am anxious to do anything with mdadm, in fear that I destroy the data on the hard disk. I would be very thankful for any help.