A mirror only lets you use one disk in a stack in usable space (50%, or less if for some reason you want a double redundant mirror, i.e. three disks). A RAID-Z ...

Am I missing something here... ? It was my understanding that with a RAID setup, it was possible to increase performance (not taking into account reliability) above that of a single disk. Let's say I ...

Pick the wrong RAID level, and you might end up losing all your data ...