What is there to handle? I have a ZFS array that works just fine with hard drives that automatically spin down. ZFS handles this without an issue.
The main gotchas tend to be: if you use the array for many things, especially stuff that throws off log files, you will constantly be accessing that array and resetting the spin down timers. Or you might be just at the threshold for spindown and you'll put a ton of cycles on it as it bounces from spindown to access to spin up.
For a static file server (rarely accessed backups or media), partitioned correctly, it works great.
The main gotchas tend to be: if you use the array for many things, especially stuff that throws off log files, you will constantly be accessing that array and resetting the spin down timers. Or you might be just at the threshold for spindown and you'll put a ton of cycles on it as it bounces from spindown to access to spin up.
For a static file server (rarely accessed backups or media), partitioned correctly, it works great.