1. Hard Drives Non-Volatile Storage

2. Hard Drives Hard Drives (HD) The primary storage device in a computer system

3. Hard Drives Invented in 1950’s Also called: Fixed Disks Hard Disks Primary Storage

4. Hard Drives Common Capacities: 20 GB 30 GB 40 GB 60 GB 80 GB 100 GB 120 GB 160 GB 200 GB 300 GB 400 GB 500 GB

5. Hard Drives Data is stored as Files Files are collections of Bytes

6. Hard Drives Files are simply strings of bytes stored on the hard drive

7. Hard Drives Files are fetched into Memory by the CPU one byte at a time, and stored on the HD one byte at a time

8. Hard Drives The time to retrieve data is measured in two ways: Data Rate Seek Time

9. Hard Drives Data Rate: The data rate is the number of bytes per second that the drive can deliver to the CPU. Rates between 5 and 160 megabytes per second are common.

10. Hard Drives Seek Time: The seek time is the amount of time between when the CPU requests a file and when the first byte of the file is sent to the CPU. Times between 8 and 20 milliseconds are common.

11. Hard Drives View of a Typical Internal Hard Drive

12. Hard Drives Inside a Hard Drive

13. Hard Drives Platters: Typically spin at 3,600 to 10,000 RPM when the drive is operating. These platters are manufactured to amazing tolerances and are mirror-smooth.

14. Hard Drives Read/Write Heads Platters

15. Hard Drives Data is stored on the surface of a platter in sectors and tracks.

16. Hard Drives Tracks are concentric circles (Yellow) Sectors are pie- shaped wedges on a track (Blue)

17. Hard Drives Low-Level formatting a drive establishes the tracks and sectors on the platter.

18. Hard Drives Partitioning a Hard Drive Separates the Hard Drive into Logical Pieces

19. Hard Drives Partitioning a Hard Drive Drive C: is always the first Logical drive partition of the first Hard Drive registered in the system

20. Hard Drives Partitioning Example: 80 GB One Primary Partition Drive C:

21. Hard Drives Partitioning Example: 20 GB Primary C: Logical D: Logical E: Logical F:

22. Hard Drives High-level formatting writes the file- storage structures, like the file- allocation table, into the sectors. This process prepares the drive to hold files.

23. Hard Drives Head Crash Causes Physical Damage to the Hard Drive Platters Catastrophic Data Not Usually Recoverable

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25. Hard Drives Fragmentation of Hard Drive Defragmentation of Hard Drive

26. Hard Drives Fragmentation of Hard Drive Occurs as files are written to the hard drive during normal operation Files are written out of consecutive order

27. Hard Drives Defragmentation of Hard Drive Resetting the files back in consecutive order on the Hard Drive Via a Defrag Program

28. Hard Drives Hard Drive Manufacturers MaxtorSeagate Western Digital FujitisuSamsung

29. Hard Drives Hard Drive Types IDESCSIUSBFIREWIRE

30. Hard Drives IDE Integrated Drive Electronics 5400 – 7200 RPM ATA-100/133 MB/Sec UDMA-5

31. Hard Drives Cable Types: IDE 40/50 Pin & 80 Pin

32. Hard Drives SCSI Small Computer System Interface 5400 – 10,000 RPM SCSI, SCSI-2, SCSI-3 Ultra-SCSI, Ultra-Wide SCSI, Ultra-160 SCSI, Ultra-320 SCSI

33. Hard Drives Cable Types: SCSI (Over 20 Connection Types)

34. Hard Drives RAID Redundant Array of Independent Disks

35. Hard Drives RAID Levels Level 0: Provides Data Striping

36. Hard Drives RAID Levels Level 1: Provides Disk Mirroring

37. Hard Drives RAID Levels Level 0 + 1 Combines both Data Stripping and Data Mirroring

38. Hard Drives RAID Levels Level 5: Provides data striping at the byte level and also stripe error correction information. This results in excellent performance and good fault tolerance.

39. Hard Drives STRIPPING Requires at least 2 HDs to work Should be same type, speed, size

40. Hard Drives Mirroring Requires at least 2 HDs to work Should be same type, speed, size

41. Hard Drives Questions