man pages section 1M: System Administration Commands

The Solaris 10 10/08 release includes modifications to support the Solaris CIFS environment as described in the zfs(1M) man page. However, the CIFS features are not supported in the Solaris 10 release. Therefore, these properties are set to read-only values. If you attempt to reset the CIFS-related properties, you will see a message similar to the following:

# zfs set utf8only=on rpool
cannot set property for 'rpool': 'utf8only' is readonly