Re:Don’t Be Afraid of RAID
by magicalhippo on Sunday May 24, 2020 @06:06PM
(#23295269)
> but you will be limited to the utilization of the lowest capacity drive on the larger drives in the pool
Small, but important, correction: the drive size limiting is per vdev. A pool consist of one or more vdevs.
So say you have a pool consisting of two mirrored vdevs, one with a pair of 3TB and one with a pair of 4TB drives, and one 3TB drive dies. If your local supplier don't have the same 3TB disk in stock, you can take a 4TB or similar and pair it with the old 3TB.
The pool will then still have a capacity of 3+4 = 7TB, but at least each mirrored pair will be intact.
You can use different sized drives in ZFS, but you will be limited to the utilization of the lowest capacity drive on the larger drives in the pool. In practice this isn't much of a problem, because you can just replace the lowest capacity drives first to grow your pool size over time.