Media aware distributed data layout

A storage system comprises a plurality of vdisks, with each vdisk containing a plurality of storage segments, and each segment providing a specific class of service (CoS). Each vdisk stores files with data and meta data distributed among its storage segments. A storage system includes a memory having multiple classes of service. The system includes an interface for storing a file as blocks of data associated with a class of service in the memory. The interface chooses the class of service for a block on a block by block basis.