Review the following points when troubleshooting ZFS migration problems:
If the file system to be migrated is not set to read-only, then not all data will be migrated.
If the target file system is not empty when the shadow property is set, the data migration will not begin.
If you add or remove data from the file system to be migrated when the migration is in progress, those changes might not be migrated.
If you attempt to change the mount of the shadow file system when the migration is in progress, you will see the following message:
# zfs set mountpoint=/users/home/data users/home/shadow3 cannot unmount '/users/home/shadow3': Device busy