The fastest, costlier and relatively small form of storage managed by computer system hardware is:

Cache memory, also called CPU memory, is random access memory (RAM) that a computer microprocessor can access more quickly than it can access regular RAM. Cache is the fastest and most costly form of storage. For example, Level 1 (L1) cache is extremely fast but relatively small, and is usually embedded in the processor chip (CPU). Cache memory is volatile and managed by the computer system hardware.