ZFS

Western Digital Greens
There are many people who caution against using Western Digital Green drives in a ZFS array. Yes, they're slow. Yes, they can be unreliable. But yes, they're cheap and they don't consume much power either. I've had good results in using these in a backup system and a media server. I wouldn't recommend anything less than a raidz2 though.

Specifying ashift=12 for 4K blocks will increase your write performance roughly 10% on Advanced Format Drives like the Greens.

Check and Mail on Failed Drives
I run this script every 20 minutes in crontab:
 * /20 * * * * /usr/local/sbin/zpool-status 2&>1 >/dev/null