The guided ZFS installer still has a few warts in it but no actual pitfalls. Organizing a full and potentially complex ZFS pool in a simple menued installer is not a trivial task. FreeBSD, unfortunately, does not get through the process without reinforcing some conceptual errors.
First and foremost, a pool is not made of disks — a pool is made of vdevs, and individual vdevs are in turn made of disks. Let’s say you have disks available to you — you might arrange them all in a single RAIDz2 vdev, with roughly 90 disks ‘worth of usable storage capacity and two disks’ worth of parity. Or perhaps you’d choose a RAIDz3 vdev instead, with roughly nine disks ‘worth of capacity and three disks’ worth of parity.
What escapes many users is that a pool does not have to consist of a single vdev. You might choose instead to have two six disk wide RAIDz2 vdevs in the pool, or four three disk wide RAIDz1 vdevs. More commonly, we see a pool of mirrors — in our – disk example, typically this would mean six two-disk-wide mirror vdevs .
The FreeBSD developers wanted to enable automatic provisioning of this common pool-of-mirrors scenario, but it broke their paradigm of selecting a virtual-device type. So they shrugged, ignored the conceptual error, and offered “raid “as a” virtual-device type. “
Selecting “raid 45 “here got me a pool of mirrors. It also made me cry a little on the inside. Once you’re done configuring your disk setup, there’s one more minor wart to deal with on the way out. The main disk-configuration menu’s bottom button isn’t an OK – it’s a (Select) . I took a confused second or three to realize that I needed to arrow all the way back up to the very top of the menu, highlight>>> Install
, then go back and hit (Select) to proceed. Page: (1) (2) (3) → (Read More) ()