I recently upgraded my home TrueNAS server and migrated 18 TB of data from a 4-disk RAIDZ1 ZFS pool to a new RAIDZ2 pool.The neat part is that I did it with only three additional 8 TB disks and never transferred my data to external storage.Upgrading from RAIDZ1 to RAIDZ2 without moving data to external storage is tricky because:You can’t convert a RAIDZ1 pool to a RAIDZ2 pool in place.You can’t shrink a ZFS pool to a smaller number of disks.You can’t fit 18 TB of data on a 3-disk, 8TB RAIDZ2 poo...