This made possible transfer everything fast with ZFS replication (let’s call A your old pool, B the new one)
- perform a backup (always a good choice)
- shutdown down the server
- add all the disks
- create the new raidz1 pool B
- added with edit stops all apps or VM
- setup an insite push replication task, A as source, B as target. Recursive and full file system options must be selected
- run the job just once, will be pretty fast
- when finished, export your A pool WITHOUT nor erase configuration and wipe disks (so you still have your data in)
- rename B pool with the previous A pools name