A thin provisioned storage system may have a file system manager that presents a logical storage system to a user and a storage management system that manages physical storage devices. When a block of data is freed at the logical layer, the file system manager may identify the freed block and send a command to the physical layer. The physical layer may identify the corresponding physical block or blocks and free those blocks on the physical layer. The storage management system may use a table to manage the location of blocks of data across multiple physical storage devices.