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UNH InterOperability Lab

Serial Attached SCSI (SAS) Clause 5 Considerations. UNH InterOperability Lab. Presentation Topics. Transmission Speeds and Unit Intervals OOB Construction Differential Signaling. Physical Link Rate (Nominal). 1.5 Gbps SAS 150 MBps (MegaBytes Per Second) 3.0 Gbps SAS 300 MBps

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UNH InterOperability Lab

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  1. Serial Attached SCSI (SAS)Clause 5 Considerations UNH InterOperability Lab

  2. Presentation Topics Transmission Speeds and Unit Intervals OOB Construction Differential Signaling

  3. Physical Link Rate (Nominal) 1.5 Gbps SAS 150 MBps (MegaBytes Per Second) 3.0 Gbps SAS 300 MBps 6.0 Gbps SAS 600 MBps

  4. Unit Intervals (Nominal) 1.5 Gbps SAS 666.66666 ps (picoseconds) = 2000/3 ps 3.0 Gbps SAS 333.33333 ps = 1000/3 ps 6.0 Gbps SAS 166.66666 ps = 500/3 ps

  5. Baud Rate (Nominal) 1.5 Gbps SAS 1.5 Gigasymbols/s 3.0 Gbps SAS 3.0 Gigasymbols/s 6.0 Gbps SAS 6.0 Gigasymbols/s

  6. OOB Signal Construction Out-Of-Band Signals Consists of Bursts Dwords and Gaps of DC Idle Built with D24.3 characters 110011 0011 001100 1100

  7. OOB Interval Minimum 665.06666 ps = 666.66666 x (1 – 0.0024) Nominal 666.66666 ps Maximum 668.26666 ps = 666.66666 x (1 + 0.0024) 1 OOBI = 666.66666 ps (Nominal)

  8. OOB Signals Built from three parts: Bursts, Idles, Negations Three different signals COMWAKE COMINIT/COMRESET COMSAS

  9. COMWAKE SATA Signal Special use for new features in SAS-2 Burst Time 160 OOBI (106.66666 ns) Idle Time 160 OOBI (106.66666 ns) Negation Time 280 OOBI (186.66666 ns) Total Signal Time 2200 OOBI (1466.6666 ns)

  10. COMWAKE 160 OOBI Each Total Time: 2200 OOBI 280 OOBI 160 OOBI Each

  11. COMINIT/COMRESET SATA and SAS Signal Used to Initialize and Reset the entire connection Burst Time 160 OOBI (106.66666 ns) Idle Time 480 OOBI (320 ns) Negation Time 800 OOBI (533.33333 ns) Total Signal Time 4640 OOBI (3093.3333 ns)

  12. COMINIT/COMRESET 160 OOBI Each 800 OOBI 480 OOBI Each Total Time: 4640 OOBI

  13. COMSAS SAS Only Signal Used to communicate that a device is a SAS device Burst Time 160 OOBI (106.66666 ns) Idle Time 1440 OOBI (960 ns) Negation Time 2400 OOBI (1600 ns) Total Signal Time 12000 OOBI (8000 ns)

  14. COMSAS 160 OOBI Each 2400 OOBI 1440 OOBI Each Total Time: 12000 OOBI

  15. Detecting OOB Signals Signals are detected via Idle times NOTBurst times Burst Tolerances MAY detect all any burst <= 100ns SHALL detect all bursts > 100ns

  16. Idle Time Detection Requirements COMWAKE MAY Detect 35 ns <= Tidle < 175 ns SHALL Detect 101.3 ns <= Tidle <= 112 ns SHALL NOT Detect Tidle < 35 ns Tidle >= 175 ns

  17. Idle Time Detection Requirements COMINIT/COMRESET MAY Detect 175 ns <= Tidle < 525 ns SHALL Detect 304 ns <= Tidle <= 336 ns SHALL NOT Detect Tidle < 175 ns Tidle >= 525 ns

  18. Idle Time Detection Requirements COMSAS MAY Detect 525 ns <= Tidle < 1575 ns SHALL Detect 911.7 ns <= Tidle <= 1008 ns SHALL NOT Detect Tidle < 525 ns Tidle >= 1575 ns

  19. Differential Signaling Used to aid in handling noise on the line One + signal and one – signal transmitting in each direction

  20. Differential Signaling

  21. Differential Signaling Negative Signal is subtracted from the positive signal at the receiver

  22. Differential Signaling Result Because ‘opposite’ signals were transmitted initially; output signal is twice as powerful Noise will, theoretically, be applied equally to both channels of the differential signal; noise is eliminated from the output signal

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