No comment on the access time and having only one drive means reading only one disc at once. This puts this storage solution in the realm of "I don't need this data within an hour" so I presume the application this system acts as redundancy for failed disks.
The Facebook open computer definition for "cold storage":
"where data is stored on disk but almost never read again, like legal data or backups of third copies of data — keep on increasing dramatically, there are huge demands for developing some form of cold storage system with the highest capacity and the lowest cost."
