TAILIEUCHUNG - Operating System Concepts (14)

Module 14: Tertiary-Storage Structure• Tertiary Storage Devices.• Operating System Issues.• Performance Issues. Silberschatz and Galvin 1999 Tertiary Storage Devices.• Low cost is the defining characteristic of tertiary storage• Generally, tertiary storage is built using removable media.• Common examples of removable media are floppy disks and. CD-ROMs; other types are available Silberschatz and Galvin 1999 Removable Disks.• Floppy disk — thin flexible disk coated with magnetic material,. enclosed in a protective plastic case – Most floppies hold about 1 MB; similar technology is. used for removable disks that hold more than 1 GB – Removable magnetic disks can be nearly as fast as hard. disks, but they are at a greater risk of damage from. exposure Silberschatz and Galvin 1999 Removable Disks (Cont.).• A magneto-optic disk records data on a rigid platter coated. with magnetic material – Laser heat is used to amplify a large, weak magnetic. field to record a bit – Laser light is also used to read data (Kerr effect) – The magneto-optic head flies much farther from the disk. surface than a magnetic disk head, and the magnetic. material is covered with a protective layer of plastic or. glass; resistant to head crashes• Optical disks do not use magnetism; they employ special. materials that are altered by laser light Silberschatz and Galvin 1999 WORM Disks.• The data on read-write disks can be modified over and over• WORM (“Write Once, Read Many Times”) disks can be. written only once• Thin aluminum film sandwiched between two glass or plastic. platters• To write a bit, the drive uses a laser light to burn a small hole. through the aluminum; information can be destroyed by not. altered• Very durable and reliable• Read Only disks, such ad CD-ROM and DVD, com from the. factory with the data pre-recorded Silberschatz and Galvin 1999 Tapes.• Compared to a disk, a tape is less expensive and holds more. data, but random access is much slower• Tape is an economical medium for purposes that do not. require fast random access, ., backup copies of disk data,. holding huge volumes of data• Large tape installations typically use robotic tape changers. that move tapes between tape drives and storage slots in a. tape library – stacker – library that holds a few tapes. – silo – library that holds thousands of tapes.• A disk-resident file can be archived to tape for low cost. storage; the computer can stage it back into disk storage for. active use. Silberschatz and Galvin 1999 Operating System Issues.• Major OS jobs are to manage physical devices and to present. a virtual machine abstraction to applications.• For hard disks, the OS provides two abstraction:. – Raw device – an array of data blocks – File system – the OS queues and schedules the. interleaved requests from several applications Silberschatz and Galvin 1999 Application Interface.• Most OSs handle removable disks almost exactly like fixed. disks — a new cartridge is formatted and an empty file system. is generated on the disk• Tapes are presented as a raw storage medium, ., and. application does not not open a file on the tape, it opens the.

• Sáng kiến kinh nghiệm
• Operating system concepts
• Lecture Operating system concepts
• Operating system
• Operating system services
• Operating system structures
• Operating system design
• Operating system structure
• Hệ điều hành
• Lecture Operating system principles
• Computer system
• Modern operating systems
• Evolution of operating systems
• Multiprocessor operating systems
• Operating systems
• Lecture Operating systems
• Structure of operating systems
• Distributed operating systems
• Memory management
• Computer system organization
• Operating system concept
• File systems
• Operating systems design
• Operating systems capabilities
• Network operating system
• Operating System Debugging
• Operating System Generation
• Types of System Calls
• Bài giảng Hệ điều hành
• Lecture Advanced Operating Systems
• Advanced Operating Systems
• Bài giảng Hệ điều hành nâng cao
• Server operating systems
• PC operating systems
• Main frame operating systems
• Real time operating systems
• History of operating systems
• The operating system zoo
• Computer hardware review
• System calls
• Computer system structures
• Operations on processes
• Thread libraries
• CPU scheduling
• Process synchronization
• Handling deadlocks
• Virtual memory
• File system interface
• File system implementation
• Application I O interface
• Mass storage systems