dCache can only drive intelligent Tertiary Storage
      Systems. This essentially means that tape robot and tape drive
      operations must be done by the TSS itself and that there is
      some simple way to abstract the file PUT,
      GET and REMOVE operation.
    
Most migrating storage systems provide a regular POSIX file system interface. Based on rules, data is migrated from primary to tertiary storage (mostly tape systems). Examples for migrating storage systems are:
	Some tape systems provide a simple PUT,
	GET, REMOVE
	interface. Typically, a copy-like application writes a disk
	file into the TSS and returns an identifier which uniquely
	identifies the written file within the Tertiary Storage
	System. The identifier is sufficient to get the file back to
	disk or to remove the file from the TSS. Examples are:
	
 
   