Trouble
Change device number (minor)
if something messes up because the mdadm (suddenly) changed
minor number of my md-devices make a backup of your data and follow these steps…
why this changed suddenly … i have no idea.
i created it using md0, md1, a.s.o.
my system began to throw write-errors, while running…
after reboot it didn’t come up again as my device number changed from /dev/md1 to /dev/md127
# mdadm --detail /dev/md127
/dev/md127:
Version : 0.90
Creation Time : Wed Sep 14 10:14:13 2011
Raid Level : raid1
Array Size : 475788992 (453.75 GiB 487.21 GB)
Used Dev Size : 475788992 (453.75 GiB 487.21 GB)
Raid Devices : 2
Total Devices : 2
Preferred Minor : 127
Persistence : Superblock is persistent
[...]shows you the preferred minor: 127 (which is stored in the superblock)
So, you need to stop the array and rebuilt it
# mdadm --stop /dev/md127
# mdadm --assemble --update=super-minor /dev/md1 /dev/sdb8 /dev/sda8
tell your initrd image about the new device:
update-initramfs -u