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

2. Improving Networks Worldwide.

3. 3 SAS Clause 5 Considerations Presentation Topics Transmission Speeds and Unit Intervals OOB Construction Differential Signaling

4. 4 SAS Clause 5 Considerations 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

5. 5 SAS Clause 5 Considerations 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

6. 6 SAS Clause 5 Considerations 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

7. 7 SAS Clause 5 Considerations 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

8. 8 SAS Clause 5 Considerations 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)

9. 9 SAS Clause 5 Considerations OOB Signals Built from three parts: –Bursts, Idles, Negations Three different signals –COMWAKE –COMINIT/COMRESET –COMSAS

10. 10 SAS Clause 5 Considerations 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)

11. 11 SAS Clause 5 Considerations COMWAKE 160 OOBI Each 280 OOBI 160 OOBI Each Total Time: 2200 OOBI

12. 12 SAS Clause 5 Considerations 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)

13. 13 SAS Clause 5 Considerations COMINIT/COMRESET 480 OOBI Each 160 OOBI Each 800 OOBI Total Time: 4640 OOBI

14. 14 SAS Clause 5 Considerations 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)

15. 15 SAS Clause 5 Considerations COMSAS 1440 OOBI Each 160 OOBI Each 2400 OOBI Total Time: 12000 OOBI

16. 16 SAS Clause 5 Considerations Detecting OOB Signals Signals are detected via Idle times NOT Burst times Burst Tolerances –MAY detect all any burst <= 100ns –SHALL detect all bursts > 100ns

17. 17 SAS Clause 5 Considerations Idle Time Detection Requirements COMWAKE – MAY Detect 35 ns <= T idle < 175 ns – SHALL Detect 101.3 ns <= T idle <= 112 ns – SHALL NOT Detect T idle < 35 ns T idle >= 175 ns

18. 18 SAS Clause 5 Considerations Idle Time Detection Requirements COMINIT/COMRESET – MAY Detect 175 ns <= T idle < 525 ns – SHALL Detect 304 ns <= T idle <= 336 ns – SHALL NOT Detect T idle < 175 ns T idle >= 525 ns

19. 19 SAS Clause 5 Considerations Idle Time Detection Requirements COMSAS – MAY Detect 525 ns <= T idle < 1575 ns – SHALL Detect 911.7 ns <= T idle <= 1008 ns – SHALL NOT Detect T idle < 525 ns T idle >= 1575 ns

20. 20 SAS Clause 5 Considerations Differential Signaling Used to aid in handling noise on the line One + signal and one – signal transmitting in each direction

21. 21 SAS Clause 5 Considerations Differential Signaling

22. 22 SAS Clause 5 Considerations Differential Signaling Negative Signal is subtracted from the positive signal at the receiver

23. 23 SAS Clause 5 Considerations 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