I have a Fantom 6TB external hard drive that uses two 3TB hard drives. On the back it has two switches for setting up RAID. I have it set to RAID 0 so I can use the full 6TB. The problem with it is that it won't power on. So I pulled the hard drives out to get to the data. And for those of you wondering I did buy a new power supply and I changed the cooling fan inside it and still no power. I put the two 3TB hard drives in my computer then went into the bios and whiched the SATA controller to RAID. After that I booted into to Ubuntu 12.04 and I noticed that they weren't mounted. So I opened Disk Utility and I can see the two drives there but I can not mount them. I assume the reason is that the two drives were previously being used in RAID 0 and I need to set up the RAID array in Disk Utility but I don't quite know what I am doing and I don't want to lose the data. Oh and yes my motherboard does support 3TB.


You can set up RAID 0 with mdadm. For example, I made it visible in both Windows and Ubuntu using --build command:

# mknod /dev/md1 b 9 1
# sudo mdadm --build --verbose --chunk=64K /dev/md1 --level=0 --raid-devices=2 /dev/sdh /dev/sdi

Do not use --create command, because it will destroy your array. And remember that you should build array on every system startup. Also, set chunk size according to your array chunk size, else results will be unpredictable.

OK, mdadm is the software application and is placed inside the package of the same name. To 'enable' it you should install it:

sudo apt-get install mdadm

Chunk size is the size of the blocks on which data are divided to fit on both RAID drives. You can retrieve it from your Fantom storage settings.

And, the last: you can build your array during installation, then install Ubuntu, reboot and it should work! At least, if you have only 2 internal drives... Because drive order can change if you have > 2 drives. I'm suffering from this effect. But I found solution: run the command before mount -a runs. This should be done by runlevel injection.

But you do not need to do this, because you just have to build array once, retrieve the data and put the drives back, right? And when array is built, there will be nodes:

$ ls -l /dev/md1*
brw-rw---- 1 root disk   9, 1 sept. 10 05:30 /dev/md1
brw-rw---- 1 root disk 259, 0 sept. 10 05:30 /dev/md1p1
brw-rw---- 1 root disk 259, 1 sept. 10 05:48 /dev/md1p2
  • terminal says sudo: mdadm: command not found. Sep 9 '13 at 17:16
  • Also I don't understand "set chunk size according to your array chunk size". And yes I understand the importance of setting up the array on a system startup but for now I am trying to recover data. Sep 9 '13 at 17:21
  • Okay so as I think more about you are saying "And remember that you should build array on every system startup". Do you think I can do a fresh install using a 120GB solid state hd with the two 3TB hd's also and put the install on the 120GB hd without erasing any of the data on the 3TB hd's. If so please give me a little direction so that I feel confident that I'm doing it write Sep 9 '13 at 21:40
  • I changed my answer, check it.
    – Danatela
    Sep 9 '13 at 23:51

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.