As a sibling comment mentioned, using ZFS for RAID/storage pooling is cumbersome. On my NAS I use plain old ext4 with SnapRAID+MergerFS, which gives me the RAID

As a sibling comment mentioned, using ZFS for RAID/storage pooling is cumbersome. On my NAS I use plain old ext4 with SnapRAID+MergerFS, which gives me the RAID and checksumming features, while having the flexibility to expand the array using any combination of disks. This works rather well, and I have no need for immediate syncing/checking I would gain with ZFS. That's my main issue with ZFS. It does too many things, and is too clever/magic for my taste. Many things can go wrong when relying on a monolithic system with that much complexity. I much prefer the Unix "do one thing well" approach, and mixing purpose-built tools to suit my needs, rather than using one tool for everything.