content addressed storage
Abbreviated as CAS, an object-oriented system for storing data that are not intended to be changed once they are stored (e.g., medical images, sales invoices, archived e-mail). CAS assigns a unique identifying logical address to the data record when it is stored, and that address is neither duplicated nor changed in order to ensure that the record always contains the exact same data as were originally stored. CAS relies on disk storage instead of removable media, such as tape.
The term was coined by EMC for its Centera network storage system.