So I have just set up a 3x2TB software raid-5 array on my Ubuntu Desktop 10.04. I replaced three existing non-raid disks, but left the boot disk non-raid (the way it has always been).

Q: If the boot disk dies, is the array lost, or can I boot from a LiveCD and still access the array? I have a 10.04 server machine right next to the machine with the array in. Could that take over looking after the array if the bootdisk dies?

To be clear: I asked this over at askubuntu, to no avail. I want to know what to do in the eventuality that my boot disk goes down. Thanks.

  • You're backing up anyway, right? RAID is not a backup... – Rob Moir Jun 16 '11 at 19:35
  • Actually, yes. I have offsite backup in the form of an external HDD backing up everything that cannot be replaced. – Frank Zafka Jun 16 '11 at 19:54

The answer to your question is NO. The raid metadata is stored on the disks so you can take them to any computer running any modern Linux distribution and use mdadm to detect and start the raid array. I know that the Ubuntu Live CD doesn't include LVM but I'm not sure if it has mdadm or not. That's not really a problem it just means that you may have to run sudo apt-get update and sudo apt-get install mdadm after booting up on the Live CD. And then start the array up and mount it manually.

Other live cd's like System Rescue CD include and automatically look for LVM and mdadm (software raid) volumes. So depending on what you're looking for it may be a better option for system recovery.

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  • The Ubuntu Alternative LiveCD does include LVM and may also support your RAID array. Give it a try and see what happens. – daemonofchaos Jun 16 '11 at 18:42
  • Okay. That all makes me feel a lot better. I was concerned about having to deal with it when it was failing. I will set up a virtual machine and test out rebuilds etc. Thanks. – Frank Zafka Jun 16 '11 at 19:55

I would buy an hardware controller, HP makes some nice one's HP p200, p400 or p410

Don't know much about software raid, but if you take backup of the Host OS you should restore it and the raid is working again.

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  • Good advice. Doesn't really answer my question. I already have the 3tb raid system in place and don't have resources to purchase new equipment. I have to deal with what I got. :) – Frank Zafka Jun 16 '11 at 16:22

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