1. EET 450 – Advanced Digital Chapter 10 Hard Disk Drives

2. Interface Info Ultra2 SCSI

3. Interface Speed

4. Other Interface Technologies SCSI Fast SCSI Ultra SCSI Wide Ultra SCSI Ultra2 SCSI Wide Ultra2 SCSI Ultra3 SCSI

5. Other Interfaces Fibre Channel – Arbitrated Loop (FC- AL) 100MB/sec Up to 127 devices up to 10km apart Allows hot swapping Can be dual ported for up to 200 MB/sec

6. Other Interfaces Serial Storage Architecture 128 devices Up to 10km apart Throughput up to 160 MB/sec Data rates of 90 MB/s in non-RAID and 85MB/s in Raid mode

7. Other Interfaces Advanced Technology Attachment (ATA) AKA Ultra DMA or IDE

8. Other Interfaces CompactFlash/CF+ Type II Up to 4 Mb and above IBM has a new Microdrive Technology (1” disk) with capacity up to 340 Mb (7x CF)

9. Electro-mechanical Combination of electronics and a mechanical system Mechanical section provides ROTATION of media and STEPPING of head. Rotation is constant 3600 rpm original (synchronous) Current 5400 or 7200 rpm

10. Characteristics Latency Time delay from R/W command until head is positioned In milliseconds Data Transfer Rate Transfer of data from HD to computer interface In megabytes per second

11. Platters The number of physical media disks inside the HD Substrate – normally aluminum now Rigid base for magnetic coating Area Density Amount of data packed into an area of disk Megabits per square inch

12. Magnetic coating Oxide Media – iron oxide Thin Film Contamination causes ‘bad spots’ Read/Write heads Fly above the surface of the magnetic media 10-12 micro-inches originally Now 5 micro-inches

13. Heads Contact heads Inductive heads (gap) Magneto-resistive heads (read only) Write pre-compensation Changes strength of field due to greater density toward hub

14. Head actuator Band stepping Original – crude Servo-voice coil Dual actuator Uses multiple head advantage

15. Other characteristics Landing Zone Crash zone Park/lock Hold head during movement of drive itself Thermal compensation

16. Geometry Tracks Cylinders Sectors

17. Physical Format Sector ID Sector interleave Latency due to rotation Cylinder skewing Addressing Cyl/head/sector give absolute address

18. Physical Format CHS addressing Limited by design – 1024 cylinders, 255 heads, 63 sectors Sector Translation Logical Block addressing Doesn’t follow CHS Sector remapping Lock out bad sector

19. File System File Allocation Table FAT Clusters See tables 10.1 and 10.2 capacity versus cluster size Smallest chunk of drive used Compression NTFS – New Technology File System (NT)

20. Capacity Limits table 10.3 LimitBytescause 10 Mb 10,485,760 Hardware design 16 Mb 16,777,216 12-bit FAT 32 Mb 33,554,432 # of FAT entries 128 Mb 134,217,728 2KB cluster size 528 Mb 528,482,304 ATA vs BIOS 2 Gb 2,147,483,648 16-bit FAT 8 Gb 8,589,934,592 24-bit LBA addr

21. Performance Access time Time to get to data Data Transfer Rate Disk Caching

22. Special Drives AV Drives Cartridge drives SyQuest Bernoulli Jazz

23. Alternate Tech Magneto-Optical Phase Change Disks

24. Installation Physical Mounting location Power Setup & Operation BIOS Low-Level format G=C800:5

25. Installation Partitioning Formatting