BAIT1003 Chapter 5


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BAIT1003 Chapter 5

  1. 1. BAIT1003 IT Fundamentals Chapter 5 Storage
  2. 2. Objectives Differentiate between storage devices and storage media Describe the characteristics of an internal hard disk including capacity, platters, read/write heads, cylinders, sectors and tracks, revolutions per minute, transfer rate, and access time Discuss the purpose of network attached storage devices, external and removable hard disks, and hard disk controllers Describe the various types of flash memory storage
  3. 3. Objectives Describe cloud storage and explain its advantages Describe the characteristics of optical discs Differentiate among various types of optical discs: CDs, archive discs and Picture CDs, DVDs, and Blu-ray Discs Identify the uses of tape, magnetic stripe cards, smart cards, microfilm and microfiche, and enterprise storage
  4. 4. Storage Storage holds data, instructions, and information for future use A storage medium is the physical material on which a computer keeps data, instructions, and information
  5. 5. Storage Examples Flash memory cards USB flash drives DVD & Blu-ray disks Floppy disks Hard disk Smart Card
  6. 6. Storage Examples PC Card ExpressCard modules Tapes Microfilm & Microfiche Zip disks
  7. 7. Storage Storage features • Capacity is the number of bytes (characters) a storage medium can hold. • Examples: –Kilobyte (KB) –Megabyte (MB) –Gigabyte (GB) –Terabyte (TB) –Petabyte (PB)
  8. 8. Storage
  9. 9. Storage • A storage device is the computer hardware  records and/or retrieves items to and from storage media Reading is the process of transferring items from a storage medium into memory Writing is the process of transferring items from memory to a storage medium Storage medium memory Storage medium memory
  10. 10. Storage • Access time measures: – 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
  11. 11. Storage The access time of storage devices is slow, compared with the access time of memory.  In addition to access time, some manufacturers state a storage device’s transfer rate, because it affects access time.  Transfer rate is speed with which data, instructions and information transfer to and from a device.  Transfer rates for storage are stated in KBps (kilobytes per second), MBps (megabytes per second), and GBps (gigabytes per second)
  12. 12. Hard Disks • A hard disk contains one or more inflexible, circular platters that use magnetic particles to store data, instructions, and information
  13. 13. Hard Disks   Current personal computer hard disks have storage capacities from 160GB to 2TB and more. Hard disks are read/write storage media.
  14. 14. Hard Disks   The entire device is enclosed in airtight, sealed case to protect it from contamination. A hard disk that is mounted inside the system unit sometimes is called a fixed disk because it is not portable.
  15. 15. Hard Disks Characteristics of a hard disk include: Capacity Platters Read/Write Heads Cylinders Sectors and Tracks Revolutions per Minute Transfer Rate Access Time
  16. 16. Characteristics of Hard Disks  The capacity of a hard disk is determined from the number of platters it contains, together with composition of the magnetic coating on the platters.
  17. 17. Characteristics of Hard Disks    A typical hard disk has multiple platters stacked on top of one another. Each platter has 2 read/write heads, one for each side. The hard disk has arms  move the read/write heads to the proper locations on the platter.
  18. 18. Characteristics of Hard Disks  A read/write head is the mechanism  reads items and writes items in the drive as it barely touches the disk’s recording surface.
  19. 19. Characteristics of Hard Disks Step 2. Small motor spins platters while computer is running. Step 1. Circuit board controls movement of head actuator and a small motor. Step 4. Head actuator positions read/write head arms over correct location on platters to read or write data. Step 3. When software requests a disk access, read/write heads determine current or new location of data.
  20. 20. Characteristics of Hard Disks • Before any data can be read from or written on a hard disk, the disk must be formatted. • Formatting is the process of dividing the disk into track and sectors, so that the operating system can store and locate data and information on the disk. – A track is a narrow recording band that form a full circle on the surface of the disk. – The disk’s storage locations consist of pie-shaped sections, which break the tracks into small arcs called sectors. A sector typically stores up to 512bytes of data.
  21. 21. Characteristics of Hard Disks
  22. 22. Characteristics of Hard Disks • The location of the read/write heads often is referred to by its cylinder. • A cylinder is the vertical section of a track  passes through all platters. If a hard disk has two platters (four side), each with 1000 tracks, then it will have 1000 cylinders with each cylinder consisting of 4 tracks. (2 tracks for each platter).
  23. 23. Characteristics of Hard Disks
  24. 24. Characteristics of Hard Disks
  25. 25. Characteristics of Hard Disks    While the computer is running, the platters in the hard disk rotate at a high rate of speed. The spinning, which usually is 5400 to 15000 resolution per minute (rpm), allows nearly instant access to all tracks and sectors on the platters. Hard disks transfer rates range from 15 MBps to 320 MBps. Access time for today’s hard disks ranges from 3 to 12 ms(milliseconds).
  26. 26. Characteristics of Hard Disks   A head crash occurs when a read/write head touches the surface of a platter, usually resulting in a loss of data or sometimes loss of the entire drive. Always keep a backup of your hard disk
  27. 27. Characteristics of Hard Disks
  28. 28. Characteristics of Hard Disks • Hard disks improve their access time by using disk caching. • Disk cache sometimes called a buffer, consists of a memory chip(s) on hard disk  stores frequently accessed items. • Disk cache and memory cache work in a similar way. When a processor requests data, instruction, or information, the hard disk first checks its disk cache, before moving any mechanical part to access the platters. • The hard disks today contain between 2MB and 64MB of disk cache. The greater disk cache, the faster the hard disk.
  29. 29. Characteristics of Hard Disks
  30. 30. RAID • Redundant Array of Independent Disks • Connects multiple smaller disks into a single unit that acts like a single large hard disk. • Ideal storage solution for users who must have the data available when they attempt to access it. RAID 1 RAID 5
  31. 31. NAS • Network Attached Storage • A server connected to a network with the sole purpose of providing storage. • Any user or device connected to the network can access files on the NAS device. • Often use a RAID configuration
  32. 32. External & Removable Hard Disk There are 2 types of portable hard disk: External hard disk   It is a separate free standing hard disk that connects with a cable to a USB port on the system unit. External hard disks have storage capacities up to 6TB and more.
  33. 33. External & Removable Hard Disk There are 2 types of portable hard disk: Removable Hard Disk    It is a hard disk that inserts and removes from either a dock or a drive. Sometimes the dock or drive is built in the system unit. Removable hard disks have storage capacities up to 1 TB or more.
  34. 34. External & Removable Hard Disk External hard disks and removable hard disk offer the following advantages over the internal hard disks (fixed disks): 1. Transport a large number of files. 2. Backup important files. 3. Easily store large audio and video files. 4. Secure user data; for example, at the end of the work session, you can remove the hard disk and lock it up, leaving no data in the computer. 5. Add storage space to a notebook/ desktop without open the system unit. 6. Share a drive with multiple computers.
  35. 35. Miniature Hard Disk    Many mobile device and consumer electronics include miniature hard disks, which provide users with greater storage capacities than flash memory. Devices such as portable media players, digital cameras, smart phones, and PDAs often have built-in miniature hard disks. Miniature hard disks have storage capacities that range from 1GB to 320GB.
  36. 36. Flash Memory Cards   Flash memory cards are a type of solid-state media, which means they consist entirely of electronic components and contain no moving parts. The lack of moving part makes flash memory storage more durable and shock resistant. Common types of flash memory cards include: 1. 2. 3. 4. Solid state drives Memory cards USB flash drives Express card modules
  37. 37. Solid State Drive (SSD) • SSDs are used in all types of computers including servers, desktop computers, and mobile computers and devices such as portable media players and digital video cameras. • Storage capacities range from 16GB to 256GB and more.
  38. 38. Solid State Drive (SSD) • SSDs have several advantages over magnetic hard disks: Faster access time Faster transfer rates Generate less heat and consume less power Last longer
  39. 39. Solid State Drive (SSD)
  40. 40. Memory Cards • A memory card is a removable flash memory device that you insert and remove from a slot in a computer, mobile device, or card reader/writer.
  41. 41. Memory Cards • Common types of memory cards include:
  42. 42. USB Flash Drives    A USB flash drives, sometimes called a thumb drive is a flash memory storage device  plugs in a USB port on a computer or mobile device. Convenience for mobile users because they are small and light weight. Current USB flash drives have data transfer rates of about 12 MBps and storage capacities ranging from 512MB to 100GB.
  43. 43. Express Card Modules • It is a removable device, about 75mm long and 34mm wide or L-shaped with a width of 54mm, that fits in an ExpressCard slot. • It can be used to add memory, storage , communications, multimedia, and security capabilities to a computer. • It commonly used in notebook computers.
  44. 44. Cloud Storage Cloud storage is a service on the Web  provides storage to computer users, usually for minimal monthly fee.
  45. 45. Cloud Storage • Users subscribe to cloud storage for a variety of reasons: Access files from any computer Store large files instantaneously Allow others to access their files View time-critical data and images immediately Store offsite backups Provide data center functions
  46. 46. Optical Discs   It is a type of storage media  consists of a flat, round, portable disc made of metal, plastic and lacquer that is written and read by a laser. Optical disc primarily store software, data, digital photographs, movies, and music. Some optical disc formats are read only, meaning users cannot write (save) on the media. Others are read/write, which allows users to save on the disc just as they save on a hard disk.
  47. 47. Optical Discs   Optical discs commonly store items in a single track  spirals from the center of the disc to the edge of the disc. The single track is divided into evenly sized sectors on which items are stored. single track spirals to edge of disc disc sectors
  48. 48. Optical Discs Care of optical discs
  49. 49. Types of Optical Discs  Two general categories are: CDs DVDs  Specific format include: CD-ROM CD-R CD-RW DVD-ROM BD-ROM HD DVD-ROM DVD-R DVD+R DVD-RW DVD+RW DVD+RAM
  50. 50. Types of Optical Discs A CD-ROM can be read from but not written to • Read from a CD-ROM drive or CD-ROM player A CD-R is a multisession optical disc on which users can write, but not erase A CD-RW is an erasable multisession disc • Must have a CD-RW drive
  51. 51. Types of Optical Discs A DVD-ROM is a high-capacity optical disc on which users can read but not write or erase • Requires a DVD-ROM drive A Blu-ray Disc-ROM (BD-ROM) has a storage capacity of 100 GB DVD-RW, DVD+RW, and DVD+RAM are high-capacity rewritable DVD formats
  52. 52. Other Types of Storage Tape Magnetic stripe cards and smart cards Microfilm and microfiche Enterprise storage
  53. 53. Tape • 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
  54. 54. Magnetic Stripe Cards & Smart Cards A magnetic stripe card is a credit card, entertainment card, bank card, or other similar card, with a stripe that contains information identifying you and the card. – Information stored in the stripe includes your name, account number, and the card’s expiration data. – A magnetic stripe card reader reads information stored on the stripe.
  55. 55. Magnetic Stripe Cards & Smart Cards  A smart card, which is similar in size to a credit card or ATM card, stores data on a thin microprocessor embedded in the card.   Smart cards contain a processor and have input, process, output, and storage capabilities. When you insert the smart card in a specialized card reader, the information on the smart card is read and, if necessary, updated. E.g. prepaid telephone calling card.
  56. 56. Microfilm & Microfiche    Microfilm and microfiche store images of documents on roll or sheet film. Microfiche is a small sheet of film, usually about 4 inches by 6 inches. Microfilm is a 100 to 215 foot roll of film.
  57. 57. Microfilm & Microfiche   A computer output microfilm recorder is the device that records the image on the film. The stored images are so small that you can read them only with a microfilm or microfiche reader.
  58. 58. Microfilm & Microfiche Microfilm Reader Microfiche Reader Source: Source:
  59. 59. Microfilm & Microfiche   Application: Libraries use these media to store back issues of newspapers and magazines. Advantages: Greatly reduce the amount of paper firms must handle. Inexpensive Have longest life of any storage media Media Type Guaranteed Life Expectancy Potential Life Expectancy Magnetic disks 3 to 5 years 20 to 30 years Optical disks 5 to 10 years 50 to 100 years Solid state drives 50 years 140 years Microfilm 100 years 500 years
  60. 60. Enterprise Storage • Enterprise storage stores huge volumes of data and information for large businesses – Uses special hardware for heavy use, maximum availability, and maximum efficiency
  61. 61. Summary • This chapter identified and discussed various storage media and storage devices. Internal hard disks, external and removable hard disks, solid state drives Memory cards, USB flash drives, ExpressCard modules, cloud storage, CDs, DVDs, and Blu-ray Discs, tape, smart cards, and microfilm and microfiche