mdadm --create /dev/md1 --level 10 --raid-devices=2 /dev/sdb2 /dev/sdc2 --layout=f2 --metadata=0.90
Note that layout=f2 or layout=n2 is very importa
nt as without it you'll get a complaint like this:
mdadm --create /dev/md0 --level 10 --raid-devices /dev/sdb1 /dev/sdc1 missing missing
mdadm: invalid number of raid devices: /dev/sdb1
It is basically more like a proper/hardware based RAID 1 where you see read speeds of both drives as one.
Eg. 90MB/s drives will yield about 180-190MB/s read speeds.