How to set up DM-RAID drives in a rescue environment

After beating my head against a wall for a significant period of time because of a software RAID issue, I figured out how to set it up. Because it was so difficult I figure I would pass the savings on to you. OK here’s what we need to do. First thing is we need to figure out what our arrays are going to be made from. This is simply done with fdisk. After that we would vi /etc/mdamd.conf and add a line like this one:

DEVICE /dev/sdaN /dev/sdbN /dev/sdcN

and so on where sda/b/cN are the partitions our RAIDs are made of. Don’t worry about which is which mdadm will take care of that with the uuids.

Run this next:

mdadm –examine –brief –scan –config=partitions >> /etc/mdadm.conf

and it will put the information for the array into the config file. After this all we need to do is run:

mdadm -A /dev/mdN

for each device we want to set up. Mount as normal. Have a lot of fun


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