Storage grade refers to the access rate capabilities of disk storage. Access speed is graded as slow, medium, or fast. Performance criteria for storage grade include physical speed of disk read-write access, electronics, and buffer memory.
Slow-grade storage involves more I/O time than fast-grade storage. Cylinders on physical disk drives are often associated with slow- and medium-grade storage. Cylinders on solid-state drives can be associated with fast-grade storage.
Typically, Teradata Virtual Storage optimizes cylinder allocation by reserving fast-grade storage for frequently accessed data, and slow-grade storage for infrequently accessed data. Medium-grade storage is allocated for all other data-access frequencies.