Explain differance between Primary and secondary storage ?

• Primary and secondary storage

Computer storage is classified within primary(main) memory and secondary(peripheral) storage.
a) Primary storage is commonly RAM; ~10ns access time
b) Secondary storage is commonly hard disk drives; ~10ms access time
c) Secondary storage is a lot cheaper than primary, 3¢/Mb vs.$1/Mb.

• Secondary storage is persistent

a) Databases are stored in secondary memory, and large databases are manipulated in secondary storage.
b) We required minimising disk accesses while accessing and manipulating databases.