When creating a RAID Group and manually selecting the desired drives, all 4 of the vault drives are available to be chosen for use. However, when creating a Storage Pool, you can NOT select vault drives to be included in the Pool-- and the Automatic Drive Selection from what I've seen has never chosen any of those drives either. In my opinion this is a good thing-- but regardless I felt it was something worth pointing out. This is something I noticed while onsite with a customer (thank you!) -- and for those who may be in a pinch for storage, it's probably good info to have.