What Doesn’t It Do?
Currently, the biggest failing in ZFS is the lack of encryption. NTFS has per-file encryption, and most volume managers have a block-level encryption mechanism. Fortunately, this issue is being addressed, and ZFS can use the same mechanism that is already in place to allow compression.
Fine-grained quotas also aren’t supported. You can create growable volumes with a maximum size, but you can’t set the maximum number of files that a given user can create on a volume.