I actually did acknowledged that limitation. Maybe I wasn’t all that clear but my actual point was that requirement is where most traditional raids often fall a

I actually did acknowledged that limitation. Maybe I wasn’t all that clear but my actual point was that requirement is where most traditional raids often fall apart (even mdadm requires days of downtime to grow a vdev) so its usually better to grow the pool instead of the vdev anyway. Or in other words: if growing the vdev is a hard requirement then a traditional raid might not be the best option regardless of ZFS. It’s about picking the right tool for the job rather than moaning that ZFS doesn’t do every job perfectly (which seems to be the argument the GP was making).