SAS Interface

1.3.5.1Exception handling in the OOB sequence

When the COMINIT signal cannot be detected

When a drive sends the COMINIT signal but the COMINIT signal from the other side cannot be detected, the drive waits for the reception of the COMINIT signal from the INIT or expander until the hot-plug timeout time (500 ms) elapses. If the hot-plug timeout time elapses before the COMINIT signal from the other side has been received, the drive sends the COMINIT signal again to start a new link reset sequence. If the drive receives the COMSAS signal while waiting for the COMINIT signal, it sends the COMSAS signal and takes the OOB sequence as having been performed successfully in spite of the fact that it has not received the COMINIT signal.

When the COMSAS signal cannot be detected

When a drive sends the COMSAS signal but the COMSAS signal from the other side cannot be detected, the drive waits for the reception of the COMSAS signal from the INIT or expander until the hot-plug timeout time (500 ms) elapses. If the hot-plug timeout time elapses before the COMSAS signal from the other side has been received, the drive sends the COMSAS signal again to start a new link reset sequence.

1.3.6 SAS speed negotiation sequence

The SAS speed negotiation sequence is a peer-to-peer negotiation technique that does not assume initiator and target (i.e., host and device) roles. The sequence consists of a set of speed negotiation windows for each physical link rate, starting with 1,5 Gbps, then 3,0 Gbps, then the next rate. The length of the speed negotiation sequence is determined by the number of physical link rates supported by the phys.

Figure 1.11 defines the speed negotiation window, including:

a)speed negotiation window time;

b)rate change delay time (RCDT);

c)speed negotiation transmit time (SNTT); and

d)speed negotiation lock time (SNLT).

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Fujitsu MBA3300RC, MBC2036RC, MBC2073RC, MBA3147RC SAS speed negotiation sequence, Exception handling in the OOB sequence