crypto luks setup for tor relay from tor docs "Tor Relay Security and Best Practices": https://trac.torproject.org/projects/tor/wiki/doc/TorRelaySecurity

tor-luks.txt

# Testing out instructions on https://trac.torproject.org/projects/tor/wiki/doc/TorRelaySecurity

###############################
ROOT FS
###############################


#### FILL WITH RANDOM DATA #####
root@lappy486:/tmp# dd if=/dev/urandom of=./tor-root.img bs=1k count=25k
25600+0 records in
25600+0 records out
26214400 bytes (26 MB) copied, 2.06407 s, 12.7 MB/s


##### LOOPBACK SETUP #####
root@lappy486:/tmp# losetup /dev/loop1 ./tor-root.img

##### CRYPTO FORMAT LOOPBACK #####
root@lappy486:/tmp# cryptsetup luksFormat /dev/loop1

WARNING!
========
This will overwrite data on /dev/loop1 irrevocably.

Are you sure? (Type uppercase yes): YES
Enter LUKS passphrase: 
Verify passphrase: 


##### CRYPTO OPEN LOOPBACK #####
root@lappy486:/tmp# cryptsetup luksOpen /dev/loop1 tor-root
Enter passphrase for /dev/loop1: 
No key available with this passphrase.
Enter passphrase for /dev/loop1: 

##### FORMAT WITH EXT4 FS #####
root@lappy486:/tmp# mkfs.ext4 /dev/mapper/tor-root
mke2fs 1.42 (29-Nov-2011)
Filesystem label=
OS type: Linux
Block size=1024 (log=0)
Fragment size=1024 (log=0)
Stride=0 blocks, Stripe width=0 blocks
5904 inodes, 23552 blocks
1177 blocks (5.00%) reserved for the super user
First data block=1
Maximum filesystem blocks=24117248
3 block groups
8192 blocks per group, 8192 fragments per group
1968 inodes per group
Superblock backups stored on blocks: 
	8193

Allocating group tables: done                            
Writing inode tables: done                            
Creating journal (1024 blocks): done
Writing superblocks and filesystem accounting information: done

###############################
VAR FS
###############################

#### FILL WITH RANDOM DATA #####
root@lappy486:/tmp# dd if=/dev/urandom of=./tor-var.img bs=1k count=200k
 	204800+0 records in
204800+0 records out
209715200 bytes (210 MB) copied, 17.849 s, 11.7 MB/s


##### LOOPBACK SETUP #####
root@lappy486:/tmp# losetup /dev/loop2 ./tor-var.img


##### CRYPTO FORMAT LOOPBACK #####
root@lappy486:/tmp# cryptsetup luksFormat /dev/loop2

WARNING!
========
This will overwrite data on /dev/loop2 irrevocably.

Are you sure? (Type uppercase yes): YES


##### CRYPTO OPEN LOOPBACK #####
root@lappy486:/tmp# cryptsetup luksOpen /dev/loop2 tor-var


##### FORMAT WITH EXT4 FS #####
root@lappy486:/tmp# mkfs.ext4 /dev/mapper/tor-var
mke2fs 1.42 (29-Nov-2011)
Filesystem label=
OS type: Linux
Block size=1024 (log=0)
Fragment size=1024 (log=0)
Stride=0 blocks, Stripe width=0 blocks
50800 inodes, 202752 blocks
10137 blocks (5.00%) reserved for the super user
First data block=1
Maximum filesystem blocks=67371008
25 block groups
8192 blocks per group, 8192 fragments per group
2032 inodes per group
Superblock backups stored on blocks: 
	8193, 24577, 40961, 57345, 73729

Allocating group tables: done                            
Writing inode tables: done                            
Creating journal (4096 blocks): done
Writing superblocks and filesystem accounting information: done 


###############################
COMPLETE SETUP
###############################


##### MOUNT ROOT FS #####
root@lappy486:/tmp# mkdir /mnt/tor-root
root@lappy486:/tmp# mount /dev/mapper/tor-root /mnt/tor-root


##### MOUNT VAR FS #####
root@lappy486:/tmp# mkdir /mnt/tor-root/var
root@lappy486:/tmp# mount /dev/mapper/tor-var /mnt/tor-root/var


#### CHECK MOUNTED FILESYSTEMS #####
root@lappy486:/tmp# df -h /mnt/tor-root/
Filesystem            Size  Used Avail Use% Mounted on
/dev/mapper/tor-root   23M  1.2M   20M   6% /mnt/tor-root

root@lappy486:/tmp# df -h /mnt/tor-root/var/
Filesystem           Size  Used Avail Use% Mounted on
/dev/mapper/tor-var  192M  5.6M  177M   4% /mnt/tor-root/var

root@lappy486:/tmp# mount |grep /mnt/
/dev/mapper/tor-root on /mnt/tor-root type ext4 (rw)
/dev/mapper/tor-var on /mnt/tor-root/var type ext4 (rw)

from dmesg:
[143016.241676] EXT4-fs (dm-0): mounted filesystem with ordered data mode. Opts: (null)
[143157.477241] EXT4-fs (dm-1): mounted filesystem with ordered data mode. Opts: (null)