/dev/md2 is not a valid LUKS device

[NiceLittleRabbit]

Hello,

I am trying to install a server with 4 3.0 TB disks in RAID, following the howto from tjworld.net/wiki/Linux/Ubuntu/HardyRAID5EncryptedLVM.

The basic steps I follow are:

1. Boot on the latest Debian live DVD

# apt-get install initramfs-tools mdadm cryptsetup lvm2

# modprobe md

# modprobe linear

# modprobe multipath

# modprobe dm-crypt

# modprobe raid0

# modprobe raid1

# modprobe raid5

# modprobe raid6

# modprobe raid10

# fdisk /dev/sda (I actually use "Disk Utility" as fdisk presents some issues with large partitions. 4 partitions: 10GB, bootable, type fd, 130GB, type fd, 1900GB, type fd, Remaining space, type fd)

# sfdisk -d /dev/sda | sfdisk --force /dev/sdb

# sfdisk -d /dev/sda | sfdisk --force /dev/sdc

# sfdisk -d /dev/sda | sfdisk --force /dev/sdd

# mdadm --create /dev/md0 --level=1 --raid-devices=4 /dev/sda1 /dev/sdb1 /dev/sdc1 /dev/sdd1

# mdadm --create /dev/md1 --level=1 --raid-devices=4 /dev/sda2 /dev/sdb2 /dev/sdc2 /dev/sdd2

# mdadm --create /dev/md2 --level=5 --raid-devices=4 /dev/sda3 /dev/sdb3 /dev/sdc3 /dev/sdd3

# mdadm --create /dev/md3 --level=5 --raid-devices=4 /dev/sda4 /dev/sdb4 /dev/sdc4 /dev/sdd4

# mke2fs -t ext4 /dev/md0

# mke2fs -t swap /dev/md1

# mke2fs -t ext4 /dev/md2

# mke2fs -t ext4 /dev/md3

# KEYFILE="/media/PENDRIVE/key.png"

# cryptsetup --hash sha512 --key-size 256 --cipher aes-cbc-essiv:sha256 luksFormat /dev/md2 $KEYFILE

WARNING!
========
This will overwrite data on /dev/md2 irrevocably.

Are you sure? (Type uppercase yes): YES

# cryptsetup --hash sha512 --key-size 256 --cipher aes-cbc-essiv:sha256 luksFormat /dev/md3 $KEYFILE

WARNING!
========
This will overwrite data on /dev/md3 irrevocably.

Are you sure? (Type uppercase yes): YES

# cryptsetup --key-file $KEYFILE luksOpen /dev/md2 md2encrypted
Device /dev/md2 is not a valid LUKS device.

# cryptsetup --key-file $KEYFILE luksOpen /dev/md3 md3encrypted
Device /dev/md3 is not a valid LUKS device.

Why are they not valid LUKS devices and how should I proceed to correct that?

Thank you in advance

[manyrootsofallevil]

Can you post the output of

cat /proc/mdstat

[NiceLittleRabbit]

Personalities : [raid1] [raid6] [raid5] [raid4] [linear] [multipath] [raid0] [raid10] 
md3 : active raid5 sda4[0] sdd4[4] sdc4[2] sdb4[1]
      2814222336 blocks super 1.2 level 5, 512k chunk, algorithm 2 [4/4] [UUUU]
      
md2 : active raid5 sda3[0] sdd3[4] sdc3[2] sdb3[1]
      5566397952 blocks super 1.2 level 5, 512k chunk, algorithm 2 [4/4] [UUUU]
      
md1 : active raid1 sda2[0] sdd2[3] sdc2[2] sdb2[1]
      126952566 blocks super 1.2 [4/4] [UUUU]
      
md0 : active raid1 sda1[0] sdd1[3] sdc1[2] sdb1[1]
      9766392 blocks super 1.2 [4/4] [UUUU]

unused devices: <none>

[manyrootsofallevil]

I was hoping to find that the devices were not up.

At any rate, I've noticed that you are formatting the arrays, you should not give a filesystem to the array, you need to give a filesystem to the luks partition once it has been created.

[NiceLittleRabbit]

May it be that giving a filesystem to the array is what breaks it all?

This howto worked once, but I had to restart because I had lost the key file.

I have noticed that when I declare an array as LUKS, the computer does not seem to do anything (other than displaying the next command line), whereas when I did it and it had worked, there was a delay between the time I typed YES after

# cryptsetup --hash sha512 --key-size 256 --cipher aes-cbc-essiv:sha256 luksFormat /dev/md2 $KEYFILE

WARNING!
========
This will overwrite data on /dev/md2 irrevocably.

Are you sure? (Type uppercase yes):

and the next command line.

[NiceLittleRabbit]

OK, I solved the mystery: the arrays' LUKS' headers need to be "zeroed" before creating new ones. The following commands worked:

# head -c 1052672 /dev/zero > /dev/md2; sync
# head -c 1052672 /dev/zero > /dev/md3; sync

Thanks to all who tried to help