1 SCSI. 2 SCSI Hard Drives 3 SCSI drives are faster. SCSI drives are faster. More expensive. More expensive. Require a separate host adapter. Require.

Presentation on theme: "1 SCSI. 2 SCSI Hard Drives 3 SCSI drives are faster. SCSI drives are faster. More expensive. More expensive. Require a separate host adapter. Require."— Presentation transcript:

1 1 SCSI

2 2 SCSI Hard Drives

3 3 SCSI drives are faster. SCSI drives are faster. More expensive. More expensive. Require a separate host adapter. Require a separate host adapter. Connect in a daisy-chain. Connect in a daisy-chain. Allows multiple drives from a single host adapter using a single PCI bus slot and a single IRQ. Allows multiple drives from a single host adapter using a single PCI bus slot and a single IRQ. Allows multiple commands. Allows multiple commands.

4 4 Motherboard Slave Master ATA Drives

5 5 Motherboard Primary Slave Secondary Master ATA Drives Secondary Slave Primary Master

6 6 Motherboard SCSI Drives SCSI Host Adapter

7 7 Internal SCSI Interface Cable To Host Adapter To SCSI Drives

8 8 Internal SCSI Interface Cable

9 9 Motherboard SCSI Drives SCSI Host Adapter Terminators

10 10 Motherboard SCSI Drives SCSI Host Adapter SCSI Controller

11 11 Connecting External SCSI Devices IN OUT From SCSI Host Adapter Terminator SCSI Device SCSI Connectors

12 12 IN OUT SCSI Device Adding a SCSI Device New Device IN OUT From SCSI Host Adapter Terminator SCSI Device

13 13 SCSI Host Adapter External Internal

14 14 Two Internal and Two External SCSI Peripherals Host Adapter Internal SCSI Peripheral #1 External SCSI Peripheral #1 Internal SCSI Peripheral #2 External SCSI Peripheral # 2 Terminator

15 15 SCSI-1 Bus Width8-bits (1 byte) Bus Width8-bits (1 byte) Data Transfer Rate5 MB/s Data Transfer Rate5 MB/s Devices supported8 Devices supported8

16 16 SCSI-1 Terminator Host Adapter SCSI Peripheral Devices 0 1 2 3 4 567 SCSI Cables

17 17 SCSI-2 Fast SCSI Fast SCSI Fast Wide SCSI Fast Wide SCSI

18 18 Fast SCSI Bus Width 8-bits (1 byte) Bus Width 8-bits (1 byte) Data Transfer Rate 10 MB/s Data Transfer Rate 10 MB/s Devices supported 8 Devices supported 8

19 19 Fast Wide SCSI Bus Width16-bit (2 bytes) Bus Width16-bit (2 bytes) Data Transfer Rate20 MB/s Data Transfer Rate20 MB/s Devices supported16 Devices supported16

20 20 SCSI-3 SPI-1Ultra and Wide Ultra SPI-1Ultra and Wide Ultra SPI-2Ultra2 and Wide Ultra2 SPI-2Ultra2 and Wide Ultra2 SPI-3Ultra3 or Ultra 160 SPI-3Ultra3 or Ultra 160 SPI-4Ultra 320 SPI-4Ultra 320 SPI-5Ultra 640 SPI-5Ultra 640

21 21 SPI-1 Ultra SCSI (Sometimes called Narrow Ultra SCSI or Fast-20 SCSI) Ultra SCSI (Sometimes called Narrow Ultra SCSI or Fast-20 SCSI) Wide Ultra SCSI Wide Ultra SCSI

22 22 Ultra SCSI Bus Width 8-bit Bus Width 8-bit Data Transfer Rate 20 MB/s Data Transfer Rate 20 MB/s Devices supported 8 Devices supported 8

23 23 Wide Ultra SCSI Bus Width16-bit Bus Width16-bit Data Transfer Rate 40 MB/s Data Transfer Rate 40 MB/s Devices supported 16 Devices supported 16

24 24 SPI-2 Ultra2 SCSI (Sometimes called Fast-40 SCSI or Ultra-40 SCSI) Ultra2 SCSI (Sometimes called Fast-40 SCSI or Ultra-40 SCSI) Wide Ultra2 SCSI (Sometimes called Ultra-80 Wide Ultra2 SCSI (Sometimes called Ultra-80

25 25 Ultra2 SCSI Bus Width8-bit Bus Width8-bit Data Transfer Rate40 MB/s Data Transfer Rate40 MB/s Devices supported8 Devices supported8

26 26 Wide Ultra2 SCSI Bus Width16-bit Bus Width16-bit Data Transfer Rate80 MB/s Data Transfer Rate80 MB/s Devices supported16 Devices supported16

27 27 SPI-3 Ultra3 SCSI or Ultra-160 SCSI Bus Width16-bit Bus Width16-bit Data Transfer Rate160 MB/s Data Transfer Rate160 MB/s Devices supported16 Devices supported16

28 28 SPI-4 Ultra-320 SCSI Bus Width16-bit Bus Width16-bit Data Transfer Rate320 MB/s Data Transfer Rate320 MB/s Devices supported16 Devices supported16

29 29 SPI-5 Ultra-640 SCSI Bus Width16-bit Bus Width16-bit Data Transfer Rate640 MB/s Data Transfer Rate640 MB/s Devices supported16 Devices supported16

30 30 Data Transfer Rates (Megabytes per second) Time SCSI Fast SCSI Ultra2 SCSI Wide Ultra2 SCSI Ultra160 SCSI Wide Ultra SCSI 5 10204080160 Ultra320 SCSI Ultra640 SCSI 320640 Ultra SCSI Fast Wide SCSI

31 31 Data Transfer Rates Time SCSI-1 Fast SCSI Ultra2 SCSI Wide Ultra2 SCSI Ultra160 SCSI Wide Ultra SCSI 5MB 10MB20MB40MB80MB160MB Ultra320 SCSI Ultra640 SCSI 320MB640MB Ultra SCSI Fast Wide SCSI SCSI-2 SCSI-3 SPI-1 SPI-2 SPI-3 SPI-4 SPI-5

32 32 Narrow SCSI is 8-bits wide and accommodates 8 devices. Narrow SCSI is 8-bits wide and accommodates 8 devices. Wide SCSI is 16-bits wide and accommodates 16 devices. Wide SCSI is 16-bits wide and accommodates 16 devices.

33 33 One of the devices is always the SCSI host adaptor. Terminator SCSI Host Adapter 7 6 5 4 3 210

34 34 Disabled Terminator SCSI Host Adapter 7 6 5 4 3 0 2 1

35 35 Passive SCSI Terminators 220-Ohm Resistor 330-Ohm Resistor TERMPWR SCSI Bus Line

36 36 Active SCSI Terminator Voltage Regulator 110-Ohm Resistor TERMPWR SCSI Bus Line 2.8V

37 37 Forced Perfect Termination (FPT) A variation of active termination. A variation of active termination. Includes clamping diodes. Includes clamping diodes. Eliminates signal undershoot and overshoot. Eliminates signal undershoot and overshoot. Contributes to longer cable lengths. Contributes to longer cable lengths.

38 38 SCSI Addressing Scheme or SCSI IDs 8 devices numbered 0 through 7 8 devices numbered 0 through 7 16 devices numbered 0 through 15 16 devices numbered 0 through 15

39 39 SCSI Priority A kind of “pecking order” to determine which device gets first shot at using the SCSI bus. A kind of “pecking order” to determine which device gets first shot at using the SCSI bus. Determined by the SCSI ID. Determined by the SCSI ID.

40 40 The SCSI ID determines the priority of the SCSI device. 70654321 Highest Priority Lowest Priority

41 41 SCSI ID determines priority Terminator Host Adapter SCSI Devices 0 1 2 3 4 567

42 42 Customary SCSI IDs SCSI Host AdapterID 7 SCSI Host AdapterID 7 Primary Hard DriveID 0 Primary Hard DriveID 0

43 43 SCSI Priority 70654321 Highest Lowest 70654321 Highest 15814131211109 Lowest Narrow SCSI Wide SCSI

44 44 SCSI Bus Arbitration Device waits for bus to become free. Device waits for bus to become free. Device signals its intention to use the bus, indicating its address. Device signals its intention to use the bus, indicating its address. If a second device attempts to use the bus at the same time, the device with the higher priority wins. If a second device attempts to use the bus at the same time, the device with the higher priority wins.

45 45 Setting the SCSI ID Each SCSI device must have a unique ID. Each SCSI device must have a unique ID. The SCSI ID is set when a new SCSI device is installed. The SCSI ID is set when a new SCSI device is installed. The SCSI Host Adapter should be given SCSI ID 7. The SCSI Host Adapter should be given SCSI ID 7. May be set by hardware or in software. May be set by hardware or in software.

46 46 Setting the SCSI ID Jumpers Slide Switches 0 1 3 2 7 5 6 4 Rotary Switch

47 47 Setting the SCSI ID with Jumpers 0 1 7 654 32

48 48 IDE SCSI Wide SCSI

49 49 Logical Unit Number (LUN) A sub-level addressing scheme. A sub-level addressing scheme. Each SCSI ID can have up to 8 LUN addresses. Each SCSI ID can have up to 8 LUN addresses. Narrow SCSI allows 7 SCSI IDs times 8 LUN addresses for 56 attached devices. Narrow SCSI allows 7 SCSI IDs times 8 LUN addresses for 56 attached devices. Wide SCSI allows 15 SCSI IDs times 8 LUN addresses for 120 attached devices. Wide SCSI allows 15 SCSI IDs times 8 LUN addresses for 120 attached devices.

50 50 SCSI IDs and LUNs SCSI ID 0 SCSI ID 1 SCSI ID 2 LUN0 LUN1 LUN2 LUN3 LUN0 LUN1 LUN2 LUN3

51 51 Centronics 50-pin SCSI Connector 2 Rows of 25 Pins

52 52 Centronics 50-pin SCSI Connector

53 53 DB-25 SCSI Connector 1 1

54 54 50-pin High-density SCSI Connector Latch

55 55 50-pin High-density vs. 50-pin Centronics

56 56 68-pin, High-density SCSI Connector (HD68)

57 57 68-pin SCSI Connector used on an Internal Ribbon Cable

58 58 68-pin, Very High Density Micro Centronics Connector (VHDCI68)

59 59 80-pin Single Connector Attachment (SCA80)

60 60 50-pin High Density 68-pin High Density 80-pin SCA 50-pin Centronics

61 61 SCSI cable adapter 68-Pin Connector 50-Pin Connector

62 62 0 1 2 3 4 567 Using the SCSI cable adapter 8-bit Data 16-bit Data 68-pin to 50-pin Adapter 16-bit Devices 8-bit Devices

63 63 68-pin Cable 50-pin Cable 68-pin Cable 16-bit Data 8-bit Data 68/50 Adapter 50/68 Adapter Host Adapter

64 64 Mixing Ultra-2 and Ultra-3 SCSI Drives Ultra-2 Ultra-3 Host Adapter

65 65 SCSI Signaling Single-ended (SE) Single-ended (SE) Low Voltage Differential (LVD) Low Voltage Differential (LVD) High Voltage Differential (HVD) High Voltage Differential (HVD) Low Voltage Differential/ Single-ended Multimode (LVD/SE) Low Voltage Differential/ Single-ended Multimode (LVD/SE)

66 66 Single-ended (SE) Signaling Used by “standard” or normal SCSI Used by “standard” or normal SCSI Low cost Low cost Low performance Low performance Prone to noise Prone to noise Also called “unbalanced” signaling Also called “unbalanced” signaling

67 67 Single-ended (SE) Signaling 0 V + V

68 68 Single-ended (SE) signaling is prone to noise problems. 0 V + V Signal Noise EMI

69 69 6 Meters (About 20 feet) Single-ended (SE) signaling is limited to a maximum bus length of 6 meters. 0 1 2 3 4 567

70 70 Single-ended SCSI vs. Maximum Bus Length SCSITechnology Transfer Rate Max. Bus Length (Meters) Standard 5 Mbps 6 Wide 10 Mbps 6 Fast 3 Fast/Wide 20 Mbps 3 Ultra 3 or 1.5 Ultra/Wide 40 Mbps 3 or 1.5

71 71 Differential Signaling 0 V + V 0 V - V

72 72 Differential signaling is less prone to noise problems. 0 V + V Signal Noise EMI 0 V - V

73 73 High-voltage Differential (HVD) Low-voltage Differential (LVD)

74 74 The Problems with High-Voltage Differential (HVD) High-voltage circuits cost more than low- voltage circuits. High-voltage circuits cost more than low- voltage circuits. Not compatible with single-ended and LVD devices. Not compatible with single-ended and LVD devices. Will damage single-ended devices or LVD devices on the same bus. Will damage single-ended devices or LVD devices on the same bus.

75 75 Low-voltage Differential (LVD) Its differential signaling technique allows bus lengths up to 12 meters. Its differential signaling technique allows bus lengths up to 12 meters. Requires an LVD terminator that is different from the standard SCSI terminator. Requires an LVD terminator that is different from the standard SCSI terminator. It uses voltages that are compatible with single-ended SCSI devices. It uses voltages that are compatible with single-ended SCSI devices.

76 76 Low-voltage Differential/ Single- ended (LVD/SE) Multimode Can communicate with SE devices Can communicate with SE devices If one or more SE device is attached, the bus length restrictions are those of the SE device, not the 12 meters of LVD devices If one or more SE device is attached, the bus length restrictions are those of the SE device, not the 12 meters of LVD devices Requires the LVD terminator to work in the LVD mode. Requires the LVD terminator to work in the LVD mode.

77 77 SCSI Symbol Icons SCSISESCSILVD SCSI DIFF (HVD) SCSILVD/SE

78 78 The SCSI icons are important because: They tell you if the device will work with your system by indicating the signal type. They tell you if the device will work with your system by indicating the signal type. Putting a high-voltage differential (HVD) device in a bus with a single ended (SE) or low-voltage differential (LVD) device will cause damage. Putting a high-voltage differential (HVD) device in a bus with a single ended (SE) or low-voltage differential (LVD) device will cause damage.