modprobe raid1
If configuration uses different raid, then a different raid module should be loaded. Be it a raid 0,5,6 or whatever.
Devices can be made then
mknod /dev/md0 b 9 0
mknod /dev/md1 b 9 1
and so on. As many of them as needed.
From this point on door is open for mdadm create,assemble or whatever is needed.
Creating a device goes like this:
mdadm --create --verbose /dev/md0 --level=1 --raid-devices=2 /dev/sda2 /dev/sdc2
Linux software raid or md raid can be used as a boot device. But only if that raid device is a RAID-1 or mirror.
As boot loader, grub in this case, does not know anything about software raid that is managed by kernel, it needs to be installed on both devices on that software mirror.… Read the rest
mdadm - -add /dev/mdX /dev/sdaY
where /dev/mdX is the array that has a failed member, and /dev/sdaX is a partition that needs to be added.
/dev/sda needs to be partitioned before though.
Then it is only a matter of time to see Your arrays being syncronized.
watch -n1 'cat /proc/mdstat'
That array can be in use during that syncronization process.