Ch5 storagedevices(updated)

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  • لا مغناطيس أو ليزر
  • الوقت للعثور على البيانات المطلوبة
  • معدل نقل البيانات
  • تمت معالجتها بواسطة نظام التشغيل ( OS)  أداة
  • تحسين الأداء
  • Ch5 storagedevices(updated)

    1. 1. Chapter 5 Types of Storage Devices
    2. 2. Describing Storage Devices <ul><li>Storage devices hold data permanently, even when the computer is turned off . </li></ul><ul><li>Two processes </li></ul><ul><ul><li>Writing data </li></ul></ul><ul><ul><li>Reading data </li></ul></ul>6A-
    3. 3. Describing Storage Devices <ul><li>Storage terms </li></ul><ul><ul><ul><li>The physical material that actually holds data is called a storage medium. </li></ul></ul></ul><ul><ul><ul><ul><ul><li>A floppy disk is a storage medium. </li></ul></ul></ul></ul></ul><ul><ul><ul><li>The hardware that writes data to or reads data from a storage medium is called a storage device . </li></ul></ul></ul><ul><ul><ul><ul><ul><li>A floppy disk drive is a storage device. </li></ul></ul></ul></ul></ul><ul><li>Types of Storage Devices : </li></ul><ul><ul><ul><li>Magnetic devices use a magnet </li></ul></ul></ul><ul><ul><ul><li>Optical devices use lasers </li></ul></ul></ul><ul><ul><ul><li>Solid-state devices have physical switches </li></ul></ul></ul>6A-
    4. 4. <ul><li>Magnetic Storage Devices </li></ul><ul><li>The primary types of magnetic storage are: </li></ul><ul><ul><ul><ul><li>Hard disks. </li></ul></ul></ul></ul><ul><ul><ul><ul><li>floppy disks(Diskettes). </li></ul></ul></ul></ul><ul><ul><ul><ul><li>High-capacity floppy disks. </li></ul></ul></ul></ul><ul><ul><ul><ul><li>magnetic tape. </li></ul></ul></ul></ul><ul><li>All magnetic drives work the same </li></ul>6A- Floppy Disk Hard Disk Tape
    5. 5. Magnetic Storage Devices <ul><li>Data storage and retrieval </li></ul><ul><ul><li>A magnetic disk's medium contains iron particles, </li></ul></ul><ul><ul><li>A disk drive uses read/write heads containing </li></ul></ul><ul><ul><li>electromagnets to create magnetic charges on the </li></ul></ul><ul><ul><li>medium. </li></ul></ul>6A-
    6. 6. Magnetic Storage Devices <ul><li>Data organization </li></ul><ul><ul><li>Disks must be formatted before use </li></ul></ul><ul><li>Determines how data will be stored: </li></ul><ul><ul><li>Format draws tracks on the disk </li></ul></ul><ul><ul><li>Tracks is divided into sectors </li></ul></ul><ul><li>Purpose of formatting a magnetic disk: </li></ul><ul><ul><li>Before the computer can use a magnetic disk to store data, the disk’s surface must be magnetically formatted, so that the computer can go directly to a specific point on it without searching through data . </li></ul></ul>6A-
    7. 7. Tracks and Sectors 6A-
    8. 8. Magnetic Storage Devices <ul><li>Finding data on disk </li></ul><ul><ul><li>Each track and sector is labeled </li></ul></ul><ul><ul><li>Listing of where files are stored </li></ul></ul><ul><ul><ul><li>File Allocation Table (FAT) </li></ul></ul></ul><ul><ul><ul><li>– a log that records each File's location and each sector's status </li></ul></ul></ul><ul><ul><ul><li>FAT32 </li></ul></ul></ul><ul><ul><ul><li>NTFS </li></ul></ul></ul><ul><ul><li>The OS(Operating system) organizes sectors into groups, called clusters </li></ul></ul>6A-
    9. 9. Magnetic Storage Devices <ul><li>Diskettes </li></ul><ul><ul><li>Also known as floppy disks </li></ul></ul><ul><ul><li>Spin at 300 RPM </li></ul></ul><ul><ul><li>Takes .2 second to find data </li></ul></ul><ul><ul><li>3 ½ floppy disk holds 1.44 MB </li></ul></ul>6A-
    10. 10. Magnetic Storage Devices <ul><li>Hard disks </li></ul><ul><ul><li>Primary storage device in a computer </li></ul></ul><ul><ul><li>2 or more aluminum platters </li></ul></ul><ul><ul><li>Each platter has 2 sides </li></ul></ul><ul><ul><li>Spin between 5,400 to 15,000 RPM </li></ul></ul><ul><ul><li>Data found in 9.5 ms or less </li></ul></ul><ul><ul><li>Drive capacity greater than 40 GB </li></ul></ul>6A-
    11. 11. Illustrated Hard Disk 6A- <ul><ul><ul><li>Contain multiple disks called platters </li></ul></ul></ul>
    12. 12. Magnetic Storage Devices <ul><li>Removable high capacity disks </li></ul><ul><ul><li>Speed of hard disk </li></ul></ul><ul><ul><li>Portability of floppy disk </li></ul></ul><ul><ul><li>There are 2 types : </li></ul></ul><ul><ul><ul><ul><li>High capacity floppy disk </li></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>Stores up to 750 MB of data </li></ul></ul></ul></ul></ul><ul><ul><ul><ul><li>Hot swappable hard disks </li></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>Provide GB of data </li></ul></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>Connect via USB </li></ul></ul></ul></ul></ul>6A-
    13. 13. Magnetic Storage Devices 6A- <ul><ul><li>Hot swappable hard disks </li></ul></ul><ul><li>Hot swappable hard disk : can be removed and replaced while the computer is still running. </li></ul>
    14. 14. Magnetic Storage Devices <ul><li>Tape drives </li></ul><ul><ul><li>Best used for </li></ul></ul><ul><ul><ul><li>Infrequently accessed data </li></ul></ul></ul><ul><ul><ul><li>Back-up solutions </li></ul></ul></ul><ul><ul><li>Slow sequential access </li></ul></ul><ul><ul><li>Capacity exceeds 200 GB </li></ul></ul>6A-
    15. 15. Optical Storage Devices <ul><li>List seven types of optical storage devices commonly used in PCs. </li></ul><ul><li>Compact Disc Read-Only Memory (CD-ROM). </li></ul><ul><li>CD-Recordable (CD-R). </li></ul><ul><li>CD-ReWritable (CD-RW). </li></ul><ul><li>Digital Video Disc Read-Only Memory (DVD-ROM). </li></ul><ul><li>DVD-Recordable (DVD-R). </li></ul><ul><li>DVD-ReWritable (DVD-RW). </li></ul><ul><li>PhotoCD. </li></ul>6A-
    16. 16. Optical Storage Devices <ul><li>CD-ROM </li></ul><ul><ul><li>Most software ships on a CD </li></ul></ul><ul><ul><li>Read using a laser </li></ul></ul><ul><ul><li>Written from the inside out </li></ul></ul><ul><ul><li>Standard CD holds 650 MB </li></ul></ul>6A-
    17. 17. Recordable Optical Technologies <ul><li>CD Recordable (CD-R) </li></ul><ul><ul><li>Create a data or audio CD </li></ul></ul><ul><ul><li>Data cannot be changed </li></ul></ul><ul><ul><li>Can continue adding until full </li></ul></ul>6A-
    18. 18. Recordable Optical Technologies <ul><li>CD Rewritable (CD-RW) </li></ul><ul><ul><li>Create a reusable CD </li></ul></ul><ul><ul><li>Can reuse about 100 times </li></ul></ul>6A-
    19. 19. Recordable Optical Technologies <ul><li>Photo CD </li></ul><ul><ul><li>Provides for photo storage </li></ul></ul><ul><ul><li>Photos added to CD until full </li></ul></ul><ul><ul><li>Original pictures cannot be changed </li></ul></ul>6A-
    20. 20. Optical Storage Devices <ul><li>DVD-ROM </li></ul><ul><ul><li>Digital Video Disk </li></ul></ul><ul><ul><li>Use both sides of the disk </li></ul></ul><ul><ul><li>Capacities can reach 18 GB </li></ul></ul><ul><ul><li>DVD players can read CDs </li></ul></ul>6A-
    21. 21. Recordable Optical Technologies <ul><li>DVD Recordable (DVD-R) </li></ul><ul><ul><li>Allows home users to create DVDs </li></ul></ul><ul><ul><li>Data cannot be changed </li></ul></ul><ul><li>DVD-RAM </li></ul><ul><ul><li>Allow reusing of DVD media </li></ul></ul>6A-
    22. 22. Solid State Devices <ul><li>Data is stored physically </li></ul><ul><ul><ul><li>Store data on memory circuits. </li></ul></ul></ul><ul><li>No magnets or laser </li></ul><ul><li>Very fast </li></ul><ul><li>The primary types of Solid State Devices are: </li></ul><ul><ul><ul><li>Flash memory </li></ul></ul></ul><ul><ul><ul><li>Smart cards </li></ul></ul></ul><ul><ul><ul><li>Solid-state disks </li></ul></ul></ul>6A-
    23. 23. Solid State Devices <ul><li>Flash memory </li></ul><ul><ul><li>Found in cameras and USB drives </li></ul></ul><ul><ul><li>Combination of RAM and ROM </li></ul></ul><ul><ul><li>Long term updateable storage </li></ul></ul>6A-
    24. 24. Solid State Devices <ul><li>Solid-state disks </li></ul><ul><ul><li>Large amount of SDRAM </li></ul></ul><ul><ul><li>Extremely fast. </li></ul></ul><ul><ul><li>Require battery backups </li></ul></ul><ul><ul><li>Most have hard disks copying data </li></ul></ul>6A-
    25. 25. Solid State Devices <ul><li>Solid-state disks </li></ul>6A-
    26. 26. Solid State Devices <ul><li>Smart cards </li></ul><ul><ul><li>Credit cards with a chip </li></ul></ul><ul><ul><li>Chip stores data </li></ul></ul><ul><ul><li>A smart card contain memory and microprocessor components. </li></ul></ul><ul><ul><li>The card is made of plastic. </li></ul></ul><ul><ul><li>Hotels use for electronic keys </li></ul></ul>6A-
    27. 27. Questions <ul><li>List four types of magnetic storage devices commonly used in PCs. </li></ul><ul><li>List seven types of optical storage devices commonly used in PCs. </li></ul><ul><li>Name three types of solid-state storage devices. </li></ul><ul><li>What is the purpose of formatting a magnetic disk? </li></ul><ul><li>What is the storage capacity of a standard floppy disk? </li></ul>6A-
    28. 28. Measuring and Improving Drive Performance
    29. 29. Drive Performance <ul><li>Average access time </li></ul><ul><ul><li>Also known as seek time </li></ul></ul><ul><ul><li>Time to find desired data </li></ul></ul><ul><ul><li>Measured in milliseconds(ms) </li></ul></ul><ul><ul><li>Hard drive between 6 and 12 ms </li></ul></ul><ul><ul><li>CD between 80 and 800 ms </li></ul></ul>6B-
    30. 30. Drive Performance <ul><li>Data transfer rate </li></ul><ul><ul><li>the amount of data that one device can send to another in a given amount of time. </li></ul></ul><ul><ul><li>Measured in </li></ul></ul><ul><ul><ul><li>Bps( mega bytes per second ) </li></ul></ul></ul><ul><ul><li>Hard drive ranges from 15 to 160 MBps </li></ul></ul><ul><ul><li>Floppy disks transfer at 45 KBps </li></ul></ul>6B-
    31. 31. Data Transfer Rate 6B-
    32. 32. Optimizing Performance <ul><li>1. Disk optimization </li></ul><ul><ul><li>Handled by operating system(OS) tool </li></ul></ul><ul><ul><li>Routine disk maintenance </li></ul></ul><ul><ul><li>Optimization should be run monthly </li></ul></ul>6B-
    33. 33. Optimizing Performance <ul><li>2. Clean up unnecessary files </li></ul><ul><ul><li>Delete temp files </li></ul></ul><ul><ul><li>Uninstall unused programs </li></ul></ul><ul><ul><li>Delete obsolete data files </li></ul></ul><ul><ul><li>Files should be cleaned weekly </li></ul></ul>6B-
    34. 34. Optimizing Performance <ul><li>3. Scan a disk for errors </li></ul><ul><ul><li>Bad spots on the media </li></ul></ul><ul><ul><li>Find and fix the error </li></ul></ul><ul><ul><ul><li>Move data to a good spot </li></ul></ul></ul><ul><ul><ul><li>Mark the spot as bad </li></ul></ul></ul><ul><ul><li>Disks should be scanned monthly </li></ul></ul>6B-
    35. 35. Optimizing Performance <ul><li>4. Defragment a disk </li></ul><ul><ul><li>Files fragment when resaved </li></ul></ul><ul><ul><li>Fragmented files load slower </li></ul></ul><ul><ul><li>Defragment puts the fragments together </li></ul></ul><ul><ul><li>Disks should be defragged monthly </li></ul></ul>6B-
    36. 36. Defragment 6B-
    37. 37. Optimizing Performance <ul><li>5.File compression </li></ul><ul><ul><li>Shrinks the size of a file </li></ul></ul><ul><ul><li>Takes up less space on disk </li></ul></ul><ul><ul><li>Reduce a disks performance </li></ul></ul><ul><ul><li>Will increase disk capacity </li></ul></ul><ul><ul><li>PKZip, WinZip and WinRAR </li></ul></ul>6B-
    38. 38. File Compression 6B- 763 KB on disk Compressed 157 KB
    39. 39. Chapter 6 End of Chapter

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