According to the FNAS manual, the system dataset stores debugging core files, encryption keys for encrypted pools, and Samba4 metadata such as the user/group cache and share level permissions. Unfortunately, it seems to be impossible to let this dataset reside on a pool which is encrypted with a passphrase. So I can only store it on the boot disk. Why is there no possibility to have this dataset on an encrypted pool? Or at least have a geli passwort at boot time... This is outright ridiculous that such sensitive information can't be encrypted with a passphrase.