1. A+ Guide to Managing and Maintaining Your PC Fifth Edition Chapter 22 All About SCSI

2. 2 A+ Guide to Managing and Maintaining Your PC, Fifth Edition You Will Learn… About basics of SCSI technology and components How SCSI hard drives compare to IDE drives How to install a SCSI device Troubleshooting tips for SCSI

3. 3 A+ Guide to Managing and Maintaining Your PC, Fifth Edition SCSI Basics Standard for communication between subsystem of peripheral devices and system bus  Bus can contain/be used by up to 7 or 15 devices  Bus requires controller embedded on motherboard or host adapter inserted into an expansion slot Faster, more expensive, more difficult to install than similar IDE devices  Mostly used in corporate settings

4. 4 A+ Guide to Managing and Maintaining Your PC, Fifth Edition The SCSI Subsystem Enables two devices on SCSI bus to pass data between them without going through CPU Requires SCSI controller and unique SCSI IDs assigned to each device, including host adapter Components  Host adapters  Device drivers

5. 5 A+ Guide to Managing and Maintaining Your PC, Fifth Edition SCSI Host Adapter

6. 6 A+ Guide to Managing and Maintaining Your PC, Fifth Edition IDE versus SCSI Bus Communication

7. 7 A+ Guide to Managing and Maintaining Your PC, Fifth Edition Host Adapters Manage all devices on SCSI bus Support internal and external SCSI devices Form a single daisy chain with devices

8. 8 A+ Guide to Managing and Maintaining Your PC, Fifth Edition Considerations When Selecting a Host Adapter BIOS Expansion slot Bus mastering SCAM-compliant

9. 9 A+ Guide to Managing and Maintaining Your PC, Fifth Edition BIOS Considerations Plug and Play compatibility Built-in configuration utility Software that configures termination automatically and assigns system resources Ability to configure SCSI devices using the bus controlled by the adapter Support for up to 15 peripherals

10. 10 A+ Guide to Managing and Maintaining Your PC, Fifth Edition Expansion Slot Considerations Host adapter must fit expansion slot (eg, 16-bit ISA, PCI)

11. 11 A+ Guide to Managing and Maintaining Your PC, Fifth Edition Bus Mastering Bus master attached to PCI bus can access memory and other devices without accessing the CPU SCSI host adapter does not require a DMA channel

12. 12 A+ Guide to Managing and Maintaining Your PC, Fifth Edition SCAM-Compliant Can assign SCSI IDs dynamically at startup Two levels  Level 1 requires that the devices – but not the host adapter – be assigned an ID at startup by software  Level 2 requires that the host adapter – as well as the devices – be assigned an ID at startup by software

13. 13 A+ Guide to Managing and Maintaining Your PC, Fifth Edition SCSI Device Drivers Enable OS to communicate with a host adapter Two popular types  ASPI (Advanced SCSI Programming Interface) – more popular of the two  CAM (Common Access Method)

14. 14 A+ Guide to Managing and Maintaining Your PC, Fifth Edition Variations in SCSI Bus width Signaling methods used on SCSI cables Connectors used with SCSI cables Termination SCSI-1, SCSI-2, and SCSI-3

15. 15 A+ Guide to Managing and Maintaining Your PC, Fifth Edition Bus Width Narrow SCSI  8-bit data path  Uses a cable with a 50-pin connector (A cable) Wide SCSI  16-bit data path  Uses a cable with a 68-pin connector (P cable)

16. 16 A+ Guide to Managing and Maintaining Your PC, Fifth Edition Signaling Methods Used on SCSI Cables Single-ended (SE)Differential Send signal on pair of twisted wires – one carries voltage, one is a ground Less expensive than differential Shorter maximum cable length; data integrity is not as great Send signal on pair of twisted wires – both carry voltage; signal calculated to be the difference between the two Better signal accuracy and greater reliability HVD and LVD

17. 17 A+ Guide to Managing and Maintaining Your PC, Fifth Edition Signaling Methods Used on SCSI Cables ( continued )

18. 18 A+ Guide to Managing and Maintaining Your PC, Fifth Edition SCSI Cables

19. 19 A+ Guide to Managing and Maintaining Your PC, Fifth Edition Signaling Symbols

20. 20 A+ Guide to Managing and Maintaining Your PC, Fifth Edition Connectors Used with SCSI Cables Not affected by signaling method used Types vary in shape and pin density; can be connected with adapters Two main types:  50-pin (A cable)  68-pin (P cable) Last connector on last device must be filled with a terminator

21. 21 A+ Guide to Managing and Maintaining Your PC, Fifth Edition SCSI Connectors

22. 22 A+ Guide to Managing and Maintaining Your PC, Fifth Edition Multiple Connectors on the SCSI Bus

23. 23 A+ Guide to Managing and Maintaining Your PC, Fifth Edition Termination Prevents echo effect from electrical noise and reflected data at end of SCSI daisy chain Required at each end of a SCSI chain

24. 24 A+ Guide to Managing and Maintaining Your PC, Fifth Edition Ways to Terminate the End of a SCSI Chain Switch setting on host adapter that activates or deactivates a terminating resistor on the card Single SCSI connection or two connections Resistor physically mounted on the device Internal terminators that turn on or off with a jumper setting on the device Software-controlled termination

25. 25 A+ Guide to Managing and Maintaining Your PC, Fifth Edition External SCSI Terminator

26. 26 A+ Guide to Managing and Maintaining Your PC, Fifth Edition Terminators Types  Passive terminators  Active terminators  Forced perfect terminators (FPTs) Single-ended SCSI cables use passive terminators, active terminators, and FPTs Differential cables use either HVD or LVD terminators

27. 27 A+ Guide to Managing and Maintaining Your PC, Fifth Edition Major Versions of SCSI SCSI-1 (Regular SCSI)  No common command set  8-bit data bus  7 possible devices SCSI-2 (Fast SCSI)  Common command set  16-bit data bus  15 possible devices  Mandatory parity checking

28. 28 A+ Guide to Managing and Maintaining Your PC, Fifth Edition Major Versions of SCSI ( continued ) SCSI-3 (Ultra SCSI)  Supports both parallel and serial data transmission  Supports FireWire connections  Data transfer of 320 MB/sec  Includes SPI standard

29. 29 A+ Guide to Managing and Maintaining Your PC, Fifth Edition SCIS Standards

30. 30 A+ Guide to Managing and Maintaining Your PC, Fifth Edition SCIS Standards ( continued )

31. 31 A+ Guide to Managing and Maintaining Your PC, Fifth Edition SCIS Standard Cable Specs

32. 32 A+ Guide to Managing and Maintaining Your PC, Fifth Edition Comparing IDE and SCSI IDE  May give better performance when using a single disk drive with an OS like Windows 98 or Windows Me SCSI  Increases performance where heavy load is placed on system and its components  Some OSs include increased support for SCSI features and take better advantage of them  More expensive; better performance

33. 33 A+ Guide to Managing and Maintaining Your PC, Fifth Edition Considerations When Choosing Between IDE and SCSI Drives IDESCSI IDE supports only four internal devices Supports internal and external devices; allows additional ones Separate IRQ required for each device Only one IRQ required for entire chain Generally backward-compatible Only one IDE drive on an IDE channel can be busy at a time Two or more devices can operate simultaneously

34. 34 A+ Guide to Managing and Maintaining Your PC, Fifth Edition More SCSI Considerations Drives perform better in RAID array Devices are generally of higher quality and more expensive Hard drive with supporting host adapter and cable costs more than an IDE hard drive

35. 35 A+ Guide to Managing and Maintaining Your PC, Fifth Edition More SCSI Considerations ( continued ) Subsystem provides faster data transfer Generally provides better performance  Often used on high-demand servers A good SCSI host adapter allows connection of other SCSI devices to it

36. 36 A+ Guide to Managing and Maintaining Your PC, Fifth Edition Basic Steps for Installing SCSI Devices 1.Set jumpers or switches on host adapter; install it on motherboard; install host adapter drivers 2.Assign SCSI ID with jumpers or switches 3.Attach cabling to host adapter and each device

37. 37 A+ Guide to Managing and Maintaining Your PC, Fifth Edition Basic Steps for Installing SCSI Devices ( continued ) 4. Verify termination at both ends of SCSI chain 5. Power up one device at a time 6. Install drivers and software needed to interface between SCSI subsystem and OS

38. 38 A+ Guide to Managing and Maintaining Your PC, Fifth Edition Installing a Host Adapter Card Install card in expansion slot Change/verify default settings (setup program) Verify settings (Advanced Configuration Options)

39. 39 A+ Guide to Managing and Maintaining Your PC, Fifth Edition Installing a Host Adapter Card ( continued ) Windows supports host adapter  Loads device drivers automatically and installs host adapter Verify correct installation of host adapter (Device Manager) Install external SCSI device

40. 40 A+ Guide to Managing and Maintaining Your PC, Fifth Edition Installing an External SCSI Device Install software to run device (includes driver) Plug SCSI cable into host adapter port Plug other end of cable into device Set SCSI ID and install terminator on device Connect device’s power cord to wall outlet; turn on device Restart PC and test device

41. 41 A+ Guide to Managing and Maintaining Your PC, Fifth Edition Setting Device IDs During Installation Assigned automatically with SCAM-compliant SCSI subsystem Set manually without SCAM compliance; each ID must be unique  For narrow SCSI, use IDs 0-7  For wide SCSI, use IDs 0-15  Host adapter usually has ID 7

42. 42 A+ Guide to Managing and Maintaining Your PC, Fifth Edition Setting Device IDs During Installation ( continued ) For external device:  Push-button or rotary selector For internal device:  Set of jumpers on the device

43. 43 A+ Guide to Managing and Maintaining Your PC, Fifth Edition Setting IDs for External Devices

44. 44 A+ Guide to Managing and Maintaining Your PC, Fifth Edition Setting IDs for Internal Devices

45. 45 A+ Guide to Managing and Maintaining Your PC, Fifth Edition Installing a SCSI Hard Drive Host adapter and cables must be compatible with SCSI drive Configure SCSI host adapter and SCSI hard drive to communicate with each other: 1.Set SCSI IDs 2.Disable/enable disk drive and hard drive controllers 3.Check terminating resistors 4.Run CMOS setup for a SCSI system 5.Load SCSI device drivers

46. 46 A+ Guide to Managing and Maintaining Your PC, Fifth Edition SCSI Hard Drives Connectors

47. 47 A+ Guide to Managing and Maintaining Your PC, Fifth Edition General Tips for Troubleshooting SCSI Devices Keep notes and read documentation Add one SCSI device at a time Use good quality components Limit cable length

48. 48 A+ Guide to Managing and Maintaining Your PC, Fifth Edition Troubleshooting SCSI Installation Problems Turn on external devices first, then computer Check all connections Check termination (common cause of problems) Verify most updated BIOS Install PCI host adapter in PCI bus that supports bus mastering

49. 49 A+ Guide to Managing and Maintaining Your PC, Fifth Edition Troubleshooting SCSI Boot Problems Confirm BIOS setup drive configuration is set to “No Drives Installed” Verify that SCSI drive is partitioned, has a primary partition, and boot partition is set as active Back up SCSI hard drive and do low-level format on it

50. 50 A+ Guide to Managing and Maintaining Your PC, Fifth Edition Summary How SCSI technology works to provide better performance and greater expansion capabilities for many internal and external devices Advantages and disadvantages of SCSI Installation and troubleshooting guidelines