Storage Management

1. Storage Management

2. Storage Management • OS provides a uniform, logical view of information storage. • Abstracts physical properties of its storage devices to define a logical storage unit – file. • OS maps files onto physical media and accesses these files via the storage devices.

3. File-System Management

4. File System Management • Each medium is controlled by device (i.e., disk drive, tape drive) • Varying properties include access speed, capacity, data-transfer rate, access method (sequential or random) • OS responsibilities • Creating and deleting files. • Creating and deleting directories to organize files. • Supporting primitives for manipulating files and directories. • Mapping files onto secondary devices. • Backing up files on stable storage media.

5. Disk Management

6. Disk Management • Usually disks are used to store data that does not fit in the main memory or data that must be kept for a “long” period of time. • Proper management is of central importance. • The entire speed of operation of a computer may hinge on the disk subsystem and its algorithms. • OS activities • Free-space management • Storage allocation • Disk Scheduling

7. I/O Systems

8. I/O Systems • One purpose of OS is to hide the peculiarities of specific hardware devices from the user. • I/O subsystem responsible for • A memory-management component that includes buffering, caching and spooling. • A general device-driver interface • Drivers for specific hardware devices • Only the device driver knows the peculiarities of the specific device to which it is assigned.

9. Summary • Storage Management • File-System Management • Mass-Storage Management • I/O System