- Because main memory is too small to accommodate all data and programs, and because the data that it holds are lost when power is lost, the computer system must provide secondary storage to back up main memory.
- The proper management of disk storage is of central importance to a computer system. The OS is responsible for the following activities in connection with disk management:
- Free-space management,
- Storage allocation,
- Disk scheduling,
- Because secondary storage is used frequently, it must be used efficiently. The entire speed of operation of a computer may hinge on the speeds of the disk subsystem and of the algorithms that manipulate that subsystem.