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

Improving Networks Worldwide.

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

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 SAS Clause 5 Considerations Unit Intervals (Nominal) 1.5 Gbps SAS – ps (picoseconds) = 2000/3 ps 3.0 Gbps SAS – ps = 1000/3 ps 6.0 Gbps SAS – ps = 500/3 ps

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 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 – –

8 SAS Clause 5 Considerations OOB Interval Minimum – ps = x (1 – ) Nominal – ps Maximum – ps = x ( ) 1 OOBI = ps (Nominal)

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

10 SAS Clause 5 Considerations COMWAKE SATA Signal Special use for new features in SAS-2 Burst Time –160 OOBI ( ns) Idle Time –160 OOBI ( ns) Negation Time –280 OOBI ( ns) Total Signal Time –2200 OOBI ( ns)

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

12 SAS Clause 5 Considerations COMINIT/COMRESET SATA and SAS Signal Used to Initialize and Reset the entire connection Burst Time –160 OOBI ( ns) Idle Time –480 OOBI (320 ns) Negation Time –800 OOBI ( ns) Total Signal Time –4640 OOBI ( ns)

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

14 SAS Clause 5 Considerations COMSAS SAS Only Signal Used to communicate that a device is a SAS device Burst Time –160 OOBI ( ns) Idle Time –1440 OOBI (960 ns) Negation Time –2400 OOBI (1600 ns) Total Signal Time –12000 OOBI (8000 ns)

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

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

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

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 SAS Clause 5 Considerations Differential Signaling

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

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