I've been playing around with project Indiana, and the new installer and packaging system, and they are really nice.
When you install it turns the root disk into a zpool called zpl_slim,
but it doesn't let you select two disks and mirror the zpool.
Luckily you can fix this once the installation is done.
When the system has booted,
you can use the zpool attach command:
# zpool attach zpl_slim c7d0s0 c8d0s0
# zpool status
pool: zpl_slim
state: ONLINE
scrub: resilver in progress, 11.75% done, 0h3m to go
config:
NAME STATE READ WRITE CKSUM
zpl_slim ONLINE 0 0 0
mirror ONLINE 0 0 0
c7d0s0 ONLINE 0 0 0
c8d0s0 ONLINE 0 0 0
errors: No known data errors
