Not enough components to start the RAID array?

Question

I'm trying to retrieve data from a "Western Digital MyBook World Edition (white light)" NAS device. This is basically an embedded Linux box with a 1TB HDD in it formatted in ext3. It stopped booting one day for no apparent reason.

I have extracted the HDD from the NAS device and installed it in a desktop machine running Ubuntu 10.10 in the hope of accessing the files on the drive. Unfortunately, Ubuntu has not been able to mount the drive automatically.

Having started up Disk Utility I see the drive as a multi disk device called "Array (Array)" showing Metadata Version 0.90.0. The device state is: "Not Running, not enough components to start". When I click the "Start RAID Array" button I get an error saying: "Not enough components to start the RAID array".

Can you please tell me which components are missing and how to install them to get access to the drive's filesystem?

Solution

WD MyBooks use mdadm. It's a SoftRAID toolkit. I don't know why they use it in single-drive setups but there you go.

I'm guessing some bits here. I don't have one but I just want you to know: what I suggest may destroy your data. I really hope it doesn't but don't take any warranty from this post. I'm sure you have a backup ;)

sudo apt-get install mdadm

That will install mdadm (obviously) but it'll also ask to install postfix (if that isn't installed anyway). Just set it up with the default options.

Now you might be able to open up Disk Utility (palimpsest) and click Run Array. You might not.

If you can't, note the partition number for that drive (something like /dev/sdg1) and lets continue manually:

sudo mdadm --assemble --scan
# might work - it'll add a /dev/mdX device if it does

sudo mdadm --assemble --run /dev/md0 /dev/sdg1
# obviously sub in the right partition numbering

Assuming that goes well, you just need to mount the array now. You should be able to do this from nautilus' sidebar, or palimpsest, or manually:

sudo mkdir /media/raiddisk
sudo chmod 777 /media/raiddisk
sudo mount /dev/md0 /media/raiddisk

Comments

[urig]

Thank so much for all your help Oli. So here's what happened: After installed mdadm and ran sudo mdadm --assemble --scan, all 4 partitions of my drive showed up as /dev/mdX devices in Disk Utility. 3 were started in "degraded" state and 1 was stopped. Since the one I wanted was already started, I just clicked the "Mount" button in Disk Utility and it worked - I now have access to all my files and can copy them to a safe location. Once that's done I can promised in attempts to restore the MBWE software on the drive and replace it into the NAS.

[Admin]

Thanks for the answer - it helped me, too, when my RAID box failed. The data was safe on the drives, but the firmware wouldn't let me access it. Your instructions allowed me to recover the data!

[Michael Gundlach]

I believe they use mdadm because you can chain WD MyBooks together.

[Admin]

Thanks for your great answer. Helped me too when I moved to a new Windows Home Server 2011 box :)