Storage

2. Storage • What is storage? • Holds data, instructions, and information for future use. • A storage medium is the physical material on which data is stored. • Examples: DVD, CD, flash-drive, and floppy disk.

3. Storage • Capacity is the number of bytes a storage medium can hold.

4. Storage • A storage deviceis the computer hardware that records and/or retrieves items to and from storage media.

5. Storage • Access timemeasures: • The amount of time it takes a storage device to locate an item on a storage medium. • The time required to deliver an item from memory to the processor.

6. Storage • What is transfer rate? • The speed in which data, instructions, and information transfer to and from a device.

7. Hard Disks • A hard disk driveis a storage device that contains one or more inflexible, circular platters that use magnetic particles to store data, instructions, and information.

8. Trackis narrow recording bandthat forms fullcircle on disk Sectorstores up to512 bytesof data Hard Disks • How do hard disks work?

9. Hard Disks • How do hard disks work?

10. Hard Disks • Hard disks can store data using longitudinal recording or perpendicular recording

11. Hard Disks • Characteristics of a hard disk include:

12. Hard Disks • Formattingis the process of preparing a disk so that the operating system can store and locate data on the disk.

13. Hard Disks

14. How Hard Disks Work

15. Hard Disks platter track • The hard disk arms move the read/write head, which reads items and writes items in the drive • Location often is referred to by its cylinder sector read/writehead platter sides cylinder

16. Hard Disks • A head crash occurs when a read/write head touches the surface of a platter. • The platters are spinning so fast that they create a cushion of air that floats the read/write heads. The clearance is only 2 millionths of an inch (approx.) • A smoke particle, dust particle, or human hair can render a drive unusable.

17. Hard Disk Failure Detection

18. Hard Disks • A disk cache is a portion of memory located on the hard disk that stores frequently accessed items. • The hard disk first checks the disk cache for an item before it searches for items on the hard disk’s platters.

19. Hard Disks

20. Hard Disks • RAID (Redundant Array of Independent Disks) is a group of two or more integrated hard disks. • A network attached storage(NAS) device is a server connected to a network with the sole purpose of providing storage.

21. Hard Disks

22. Hard Disks • A disk controller consists of a special-purpose chip that control the transfer of data, instructions, and information from a disk to and from the computer.

23. Flash Memory Storage • Flash memory chips are a type of solid state media and contain no moving parts • Solid state drives (SSDs) have several advantages over magnetic hard disks:

24. Flash Memory Storage

25. Page 364 Flash Memory Storage • A memory cardis a removable flash memory device that you insert and remove from a slot in a computer, mobile device, or card reader/writer

26. Flash Memory Storage

27. Flash Memory Storage • USB flash drivesplug into a USB port on a computer or mobile device

28. Flash Memory Storage • An ExpressCard moduleis a removable device that fits in an ExpressCard slot • Developed by the PCMCIA • Commonly used in notebook computers

29. Cloud Storage • Cloud storage is an Internet service that provides storage to computer users. • Also called online storage.

30. Cloud Storage

31. Cloud Storage • Benefits of using cloud storage:

32. Optical Discs • An optical disc consists of a flat, round, portable disc made of metal, plastic, and lacquer that is written and read by a laser. • Typically store software, data, digital photos, movies, and music. • Some are read only while others are rewritable.

33. Optical Discs

34. Optical Discs • Optical discs commonly store items in a single track that spirals from the center of the disc to the edge. • Track is divided into evenly sized sectors.

35. Optical Discs • Care of optical discs

36. Optical Discs

37. Optical Discs

38. Other Types of Storage

39. Other Types of Storage • Tape is a magnetically coated ribbon of plastic capable of storing large amounts of data and information. • A tape drive reads and writes data and information on a tape. • Uses sequential access. • Primarily used for backup.

40. Other Types of Storage • A magnetic stripe cardcontains a magnetic stripe that stores information. • A smart cardstores data on a thin microprocessor embedded in the card.

41. Other Types of Storage • Microfilm and microfiche store microscopic images of documents on a roll or sheet film.

42. Other Types of Storage

43. Other Types of Storage • Enterprise storage stores huge volumes of data and information for large businesses • Uses special hardware for heavy use, maximum availability, and maximum efficiency

44. Hard-Drive Buying Decisions • Storage Capacity (GB – TB) • Depends on intended purpose of drive. • Cache size • Technology • SATA (fastest), EIDE, SCSI • Speed • Seek Time / Access Time • Measured in milliseconds ms. • Lower the number the better. • Transfer Rate • RPMs • Portability • External drives can be taken from computer to computer. • Internal drives are fixed inside the computer itself. • Check out this site • http://www.newegg.com

45. Funny Thought… Why doesn't glue stick to the inside of the bottle?