Linux Software RAID

to see how raids are doing

cat /proc/mdstat

or

lsraid -a /dev/md0  (or 1 or 2 etc.)

There's also a way to test out the raid by having the software mark one of the disks as faulty just as a test. Then later you set it back to normal and watch the array rebuild itself.

RAID5 Failure Recovery

When multiple drives in a raid5 has failed. First stop the raid

mdadm -S /dev/md1

then reassemble it

mdadm --assemble --scan -f /dev/md1

now you can (re)start lvm (/etc/init.d/lvm start) and mount all drives

mount -a

then re-add the failed drive if any

mdadm /dev/md1 --add /dev/sdc2