I'm using Ubuntu 13.10 and trying to create a RAID 5 array across 3 identical disks connected to SATA ports on the motherboard. I've followed every guide and and used both the built-in Disks GUI app and mdadm at the command line, and despite everything I cannot get the array to persist after reboot.
I create the array with the following command:
root@zapp:~# mdadm --create /dev/md/array --chunk=512 --level=5 \
--raid-devices=3 /dev/sda /dev/sdb /dev/sdd
Then I watch /proc/mdstat for awhile while it syncs, until I get this:
Personalities : [linear] [multipath] [raid0] [raid1] [raid6] [raid5] [raid4] [raid10]
md127 : active raid5 sda1[0] sdd1[3] sdb1[1]
1953262592 blocks super 1.2 level 5, 512k chunk, algorithm 2 [3/3] [UUU]
unused devices: <none>
To update the mdadm config file, I run the following:
root@zapp:~# /usr/share/mdadm/mkconf > /etc/mdadm/mdadm.conf
This adds the essential line to my config file:
ARRAY /dev/md/array metadata=1.2 UUID=0ad3753e:f0177930:8362f527:285d76e7 name=zapp:array
Everything seems correct, but when I reboot, the array is gone!