Seagate Ultra 320, Ultra 160 User Manual

Parallel SCSI Interface

Ultra 160

Ultra 320

Parallel SCSI Interface

Ultra 160

Ultra 320

Publication number: 100293069, Rev. A

March 2006

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Seagate reserves the right to change, without notice, product offerings or specifications. No

part of this publication may be reproduced in any form without written permission of Seagate

Technology LLC.

Revision status summary sheet

Revision Date Writer/Engineer Sheets Affected

Rev. A 03/27/06 C. Chalupa/G. Houlder All.

Parallel SCSI Interface Product Manual, Rev. A iii

iv Parallel SCSI Interface Product Manual, Rev. A

Table of Contents

1.0 Interface requirements. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

1.1 How to use this interface manual . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

1.1.1 Scope of SCSI standards . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

1.1.2 Applicable standards. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

1.2 General interface description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

1.2.1 Glossary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

1.2.2 Keywords . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

1.3 Physical interface characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

1.4 Summary of SCSI messages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

2.0 SCSI bus . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

2.1 SCSI bus signals overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

2.1.1 Drive select . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

2.1.2 Signal values. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

2.2 Signal states . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

2.2.1 SE signals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

2.2.2 LVD signals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

2.3 OR-tied signals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

2.4 Signal sources . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

2.5 SCSI bus timing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

2.5.1 Arbitration delay . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

2.5.2 ATN transmit setup time . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

2.5.3 ATN receive setup time. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

2.5.4 Bus clear delay . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

2.5.5 Bus free delay . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

2.5.6 Bus set delay . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

2.5.7 Bus settle delay. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

2.5.8 Cable skew delay . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

2.5.9 Chip noise in receiver . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

2.5.10 Clock jitter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

2.5.11 Crosstalk time shift . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

2.5.12 De-skewed data valid window. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

2.5.13 Flow control receive hold time. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

2.5.14 Flow control receive setup time. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

2.5.15 Flow control transmit hold time . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

2.5.16 Flow control transmit setup time . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

2.5.17 pCRC receive hold time . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

2.5.18 pCRC receive setup time . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

2.5.19 pCRC transmit hold time . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

2.5.20 pCRC transmit setup time . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

2.5.21 Data release delay . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

2.5.22 DIFFSENS voltage filter time . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

2.5.23 Offset induced time asymmetry. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

2.5.24 Physical disconnection delay . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

2.5.25 Power on to selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

2.5.26 QAS arbitration delay . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

2.5.27 QAS assertion delay . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

2.5.28 QAS release delay . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

2.5.29 QAS non-data phase REQ(ACK) period . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

2.5.30 Receive assertion period . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

2.5.31 Receive hold time . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

2.5.32 Receive internal hold time. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30

2.5.33 Receive internal setup time. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30

2.5.34 Receive negation period . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30

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2.5.35 Receive setup time . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30

2.5.36 Receive REQ(ACK) period tolerance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30

2.5.37 Receive REQ assertion period with P_CRCA transitioning. . . . . . . . . . . . . . . . . . . . . . . . . 30

2.5.38 Receive REQ negation period with P_CRCA transitioning . . . . . . . . . . . . . . . . . . . . . . . . . 30

2.5.39 Receive skew compensation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30

2.5.40 Receiver amplitude time skew. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

2.5.41 REQ(ACK) period . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

2.5.42 Reset delay . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

2.5.43 Reset hold time . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

2.5.44 Reset to selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

2.5.45 Residual skew error. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

2.5.46 Selection abort time. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

2.5.47 Selection timeout delay . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

2.5.48 Signal timing skew. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

2.5.49 Skew correction range. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32

2.5.50 Strobe offset tolerance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32

2.5.51 System deskew delay . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32

2.5.52 System noise at launch . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32

2.5.53 System noise at receiver . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32

2.5.54 Time asymmetry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32

2.5.55 Transmit assertion period . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32

2.5.56 Transmit hold time . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32

2.5.57 Transmit ISI compensation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32

2.5.58 Transmit negation period. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32

2.5.59 Transmit setup time . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33

2.5.60 Transmit REQ(ACK) period tolerance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33

2.5.61 Transmit REQ assertion period with P_CRCA transitioning . . . . . . . . . . . . . . . . . . . . . . . . 33

2.5.62 Transmit REQ negation period with P_CRCA transitioning. . . . . . . . . . . . . . . . . . . . . . . . . 33

2.5.63 Transmitter skew . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33

2.5.64 Transmitter time asymmetry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33

2.6 Measurement points . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33

2.6.1 SE Fast-5 and Fast-10 measurement points. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33

2.6.2 SE Fast-20 measurement points . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33

2.6.3 LVD measurement points . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34

2.7 Clocking methods for data transfers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34

2.8 Paced transfer on a SCSI bus . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36

2.9 Data transfer modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37

2.9.1 Asynchronous transfers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37

2.9.2 Synchronous transfers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37

2.9.3 Paced transfers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37

2.10 ST DATA phase parallel transfers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38

2.11 DT DATA phase parallel transfers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38

2.11.1 Data group transfers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38

2.11.2 Information unit transfers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38

2.12 Negotiation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39

2.12.1 Negotiation algorithm. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39

2.12.2 When to negotiate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40

2.12.3 Negotiable fields . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40

2.12.4 Transfer agreements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42

2.12.5 Transfer period factor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43

2.12.6 REQ/ACK offset. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44

2.12.7 Transfer width exponent . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44

2.12.8 Protocol options . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45

2.12.8.1IU_REQ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45

2.12.8.2DT_REQ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46

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2.12.8.3QAS_REQ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46

2.12.8.4HOLD_MCS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46

2.12.8.5WR_FLOW . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47

2.12.8.6RD_STRM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47

2.12.8.7RTI (Retain Training Information) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47

2.12.8.8PCOMP_EN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47

2.12.9 Negotiable field combinations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48

2.12.10 Message restrictions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49

2.12.11 Negotiation message sequences . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49

3.0 Logical characteristics. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51

3.1 SCSI bus phases overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51

3.1.1 BUS FREE phase . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51

3.1.1.1 Unexpected and expected bus free phases . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51

3.1.1.2 Expected bus free phases. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52

3.1.2 Arbitration and QAS overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52

3.1.2.1 Normal ARBITRATION phase. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53

3.1.2.2 QAS protocol . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54

3.1.2.3 QAS phase overview. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54

3.2 SELECTION phase . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55

3.2.1 Selection overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56

3.2.1.1 Selection using attention condition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56

3.2.1.1.1 Starting the SELECTION phase when using attention condition . . . . . . . . . . 56

3.2.1.1.2 Information unit transfers disabled . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56

3.2.1.1.3 Information unit transfers enabled . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56

3.2.1.1.4 Selection using attention condition timeout procedure. . . . . . . . . . . . . . . . . . 57

3.2.1.2 Selection without using attention condition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57

3.2.1.2.1 Information unit transfers disabled or enabled . . . . . . . . . . . . . . . . . . . . . . . . 57

3.2.1.2.2 Selection without using attention condition time-out procedure . . . . . . . . . . . 57

3.3 RESELECTION phase. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58

3.3.1 RESELECTION phase overview. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58

3.3.2 Physical reconnection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58

3.3.3 Physical reconnection timeout procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59

3.4 SCSI bus fairness . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59

3.5 Information transfer phases . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60

3.5.1 Asynchronous transfer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61

3.5.2 Synchronous transfer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61

3.5.2.1 ST synchronous data transfer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61

3.5.2.2 DT synchronous transfer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62

3.5.2.2.1 Information unit transfer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62

3.5.2.2.2 Data group data field transfer. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64

3.5.3 Paced transfer. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68

3.5.3.1 Paced transfer training pattern . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68

3.5.3.1.1 DT DATA IN phase training pattern . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69

3.5.3.1.2 DT DATA OUT phase training pattern . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70

3.5.3.2 P1 data valid/invalid state transitions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71

3.5.3.2.1 Starting pacing transfers at end of training pattern . . . . . . . . . . . . . . . . . . . . 72

3.5.3.2.2 Starting pacing transfers with no training pattern . . . . . . . . . . . . . . . . . . . . . . 72

3.5.3.2.3 Ending pacing transfers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73

3.5.3.3 Paced information unit transfer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73

3.5.3.4 Deskewing. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74

3.5.4 Wide transfer. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74

3.6 COMMAND phase . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75

3.6.1 COMMAND phase description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75

3.6.2 COMMAND phase exception condition handling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75

3.7 DATA phase. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75

Parallel SCSI Interface Product Manual, Rev. A vii

3.7.1 DATA phase overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75

3.7.2 DT DATA IN phase . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75

3.7.3 DT DATA OUT phase . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76

3.7.4 ST DATA IN phase . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76

3.7.5 ST DATA OUT phase . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76

3.8 STATUS phase. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76

3.8.1 STATUS phase description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76

3.8.2 STATUS phase exception condition handling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76

3.9 MESSAGE phase . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76

3.9.1 MESSAGE phase overview. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76

3.9.2 MESSAGE IN phase . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76

3.9.2.1 MESSAGE IN phase exception condition handling . . . . . . . . . . . . . . . . . . . . . . . . . . . 77

3.9.3 MESSAGE OUT phase . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77

3.9.3.1 MESSAGE OUT phase exception condition handling . . . . . . . . . . . . . . . . . . . . . . . . . 77

3.10 Signal restrictions between phases . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77

3.11 SCSI bus phase sequences . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78

3.11.1 SCSI bus phase sequences overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78

3.11.2 Phase sequences for physical reconnection and selection using attention

condition with information unit transfers disabled. . . . . . . . . . . . . . . . . . . . . . . . . . 78

3.11.3 Phase sequences for selection without using attention condition with

information unit transfers disabled . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79

3.11.4 Phase sequences for physical reconnection or selection without using

attention condition with information unit transfers enabled. . . . . . . . . . . . . . . . . . . 80

3.11.5 Phase sequences for physical selection using attention condition with

information unit transfers enabled . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81

3.12 Data bus protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81

3.12.1 Data bus protection overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81

3.12.2 ST data bus protection using parity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81

3.12.3 DT data bus protection using CRC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82

3.12.3.1DT data bus protection using CRC overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82

3.12.3.2Error detection capabilities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82

3.12.3.3Order of bytes in the CRC field . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82

4.0 Message system specification. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83

4.1 General message protocols and formats . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83

4.2 Message formats . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83

4.2.1 One-byte messages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84

4.2.2 Two-byte messages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84

4.2.3 Extended messages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84

4.3 Message categories . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85

4.3.1 LINK CONTROL MESSAGES. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85

4.3.2 DISCONNECT. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87

4.3.3 IDENTIFY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87

4.3.4 IGNORE WIDE RESIDUE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88

4.3.5 INITIATOR DETECTED ERROR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89

4.3.6 LINKED COMMAND COMPLETE. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89

4.3.7 MESSAGE PARITY ERROR. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89

4.3.8 MESSAGE REJECT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89

4.3.9 MODIFY DATA POINTER . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89

4.3.10 MODIFY BIDIRECTIONAL DATA POINTER . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90

4.3.11 NO OPERATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91

4.3.12 PARALLEL PROTOCOL REQUEST. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92

4.3.12.1PARALLEL PROTOCOL REQUEST . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95

4.3.13 QAS REQUEST. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 96

4.3.14 RESTORE POINTERS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 96

4.3.15 SAVE DATA POINTERS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 96

viii Parallel SCSI Interface Product Manual, Rev. A

4.3.16 SYNCHRONOUS DATA TRANSFER REQUEST . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97

4.3.16.1Target initiated SDTR negotiation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99

4.3.16.2Initiator initiated SDTR negotiation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99

4.3.17 TASK COMPLETE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99

4.3.18 WIDE DATA TRANSFER REQUEST . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100

4.3.18.1Target initiated WDTR negotiation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101

4.3.18.2Initiator initiated Wide Data Transfer Request (WDTR) negotiation . . . . . . . . . . . . . 102

4.4 Task attribute messages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102

4.4.1 Task attribute message overview and codes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102

4.4.2 ACA (AUTO CONTINGENT ALLEGIANCE) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103

4.4.3 HEAD OF QUEUE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 104

4.4.4 ORDERED . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 104

4.4.5 SIMPLE. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 104

4.5 Task management messages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105

4.5.1 Task management message codes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105

4.5.2 ABORT TASK . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105

4.5.3 ABORT TASK SET . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 106

4.5.4 CLEAR ACA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 106

4.5.5 CLEAR TASK SET . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 106

4.5.6 LOGICAL UNIT RESET . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 106

4.5.7 TARGET RESET . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 106

5.0 Miscellaneous SCSI bus characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107

5.1 Attention condition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107

5.2 Bus reset condition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 108

5.3 Hard reset . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 108

5.4 Reset events . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109

5.4.1 Bus reset event . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109

5.4.2 Power on reset event . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109

5.4.3 Target reset event . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109

5.4.4 Transceiver mode change reset event . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109

5.5 Asynchronous condition recovery . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109

5.5.1 SCSI pointers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109

5.5.2 Active pointers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110

5.5.3 Saved pointers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110

5.6 Command processing considerations and exception conditions . . . . . . . . . . . . . . . . . . . . . . . . . . 111

5.6.1 Command processing considerations and exception conditions overview . . . . . . . . . . . . 111

5.6.2 Asynchronous event notification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 111

5.6.3 Incorrect initiator connection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 111

5.6.4 Unexpected RESELECTION phase . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 112

6.0 SPI information units . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113

6.1 Information unit transfer logical operations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113

6.2 SPI information units . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 118

6.2.1 SPI command information unit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 118

6.2.2 SPI L_Q information unit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 121

6.2.3 SPI data information unit. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 125

6.2.4 SPI data stream information unit. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 125

6.2.5 SPI status information unit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 127

7.0 SCSI commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 131

7.1 Command implementation requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 131

7.1.1 Reserved. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 131

7.2 Command Descriptor Block (CDB) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 131

7.2.1 Fixed and variable length Command Descriptor Block formats . . . . . . . . . . . . . . . . . . . . 133

7.3 Status. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 138

Parallel SCSI Interface Product Manual, Rev. A ix

7.3.1 Status precedence. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 139

7.4 Command examples. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 140

7.4.1 Single command example . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 140

7.4.2 Disconnect example . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 141

7.5 Timing examples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 142

7.6 Command processing considerations and exception conditions . . . . . . . . . . . . . . . . . . . . . . . . . . 142

7.6.1 Auto Contingent Allegiance or Contingent Allegiance. . . . . . . . . . . . . . . . . . . . . . . . . . . . 142

7.6.1.1 Logical Unit response to Auto Contingent Allegiance or Contingent Allegiance . . . . 142

7.6.1.2 Clearing an Auto Contingent Allegiance condition. . . . . . . . . . . . . . . . . . . . . . . . . . . 143

7.6.2 Overlapped commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 143

7.6.3 Incorrect logical unit selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 144

7.6.4 Sense data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 144

7.6.4.1 Asynchronous Event Reporting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 144

7.6.4.2 Autosense . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 145

7.6.5 Unexpected RESELECTION phase . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 145

7.6.6 Unit Attention condition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 146

7.6.7 Target hard reset . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 147

7.6.8 Logical unit reset . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 147

7.7 Queued tasks (formerly “queued I/O processes”) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 147

7.7.1 Untagged task queuing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 147

7.7.2 Tagged task queuing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 148

7.8 Parameter rounding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 149

7.9 Programmable operating definition. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 149

7.10 Incorrect initiator connection. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 150

8.0 Drive features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 151

8.1 S.M.A.R.T. system . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 151

8.2 Self-test operations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 151

8.2.1 Default self-test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 151

8.2.2 The short and extended self-tests . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 151

8.2.3 Self-test modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 152

8.2.3.1 Foreground mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 152

8.2.3.2 Background mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 152

8.2.3.3 Elements common to foreground and background self-test modes . . . . . . . . . . . . . 153

8.3 Alternate error detection for the asynchronous information phases (AIP)—Command,

Message, and Status . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 154

8.3.1 Error detection for asynchronous information phases. . . . . . . . . . . . . . . . . . . . . . . . . . . . 154

8.3.2 Protection code . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 154

8.3.2.1 Covered signals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 155

8.3.2.2 Code description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 157

8.3.2.3 Error detection properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 157

8.3.3 Protection code usage. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 157

8.3.3.1 Protection code transmission. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 158

8.3.3.2 Enabling protection code checking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 158

8.3.3.3 Disabling protection code checking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 158

8.3.4 Parity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 158

8.3.5 Error handling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 158

8.4 Removal and insertion of SCSI devices (popularly known as “hot plugging”) . . . . . . . . . . . . . . . . 158

8.4.1 Removal and insertion of SCSI devices overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 158

8.4.2 Case 1—Power off during removal or insertion. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 159

8.4.3 Case 2—RST signal asserted continuously during removal or insertion. . . . . . . . . . . . . . 159

8.4.4 Case 3—Current I/O processes not allowed during insertion or removal . . . . . . . . . . . . . 159

8.4.5 Case 4—Current I/O process allowed during insertion or removal . . . . . . . . . . . . . . . . . . 159

8.5 SPI-3 to SCSI-2 terminology mapping . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 160

x Parallel SCSI Interface Product Manual, Rev. A

List of Figures

Figure 1. SCSI client-server model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

Figure 2. Voltage and current definitions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

Figure 3. LVD Signaling sense . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

Figure 4. ST latching data vs. DT latching data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35

Figure 5. ST synchronous transfer example . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35

Figure 6. DT synchronous transfer example. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36

Figure 7. Paced transfer example. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36

Figure 8. Example of a SCSI bus with paced transfers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37

Figure 9. Use of P1 to establish data valid and data invalid states . . . . . . . . . . . . . . . . . . . . . . . . . . . 72

Figure 10. Phase sequences for physical reconnection and selection using attention

condition with information unit transfers disabled . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79

Figure 11. Phase sequences for selection without using attention condition with information

unit transfers disabled . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79

Figure 12. Phase sequences for physical reconnection or selection without using attention

condition/ with information unit transfers enabled . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80

Figure 13. Phase sequences for selection with attention condition/physical reconnection

and information unit transfers enabled . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81

Figure 14. SPI information unit sequence during initial connection . . . . . . . . . . . . . . . . . . . . . . . . . . . 115

Figure 15. SPI information unit sequence during data type transfers. . . . . . . . . . . . . . . . . . . . . . . . . . 116

Figure 16. SPI information unit sequence during data stream type transfers. . . . . . . . . . . . . . . . . . . . 117

Figure 17. SPI information unit sequence during status transfers . . . . . . . . . . . . . . . . . . . . . . . . . . . . 118

Figure 18. Single command example . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 140

Figure 19. Disconnect example . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 141

Figure 20. Protection code generator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 157

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xii Parallel SCSI Interface Product Manual, Rev. A

1.0 Interface requirements

1.1 How to use this interface manual

This manual provides a description of the SCSI1 interface protocol and some general timing information as implemented by Seagate products. The features described in this manual are typically referred to as “Ultra160 SCSI” or “Ultra320 SCSI” features. Individual drive’s Product Manual, for the various SCSI interface products, contains additional and more detailed information on protocol, features supported, timing, and electrical/ mechanical aspects of how the SCSI interface is implemented by that product.

This manual provides a general, tutorial-type description of the ANSI SCSI (formerly called SCSI-3) system. It is not intended to give all of the kinds of details needed to design/implement a SCSI system or product. For information about SCSI interface details not included herein, refer to the standards listed in Section

Note. The individual drive’s Product Manual, has tables that specify which SCSI features the drive imple-

ments, what the default parameters are for the various features they implement, which parameters are changeable, and which are not.

The combination of this specification together with the details in the individual drive’s Product Manual, provides a description of how a particular product implements the SCSI I/O system. This specification is Volume 2 of a set of manuals that is made up of an individual drive’s Product Manual, and this manual. The older Ultra2 SCSI Interface Manual, part number 77738479, applies to Seagate products that implement older versions of the SCSI interface (SCSI-1/SCSI-2). This new Parallel SCSI Interface Manual, part number 100293069, is refer enced by newer individual drive’s Product Manuals, representing Seagate products that support Ultra160 or Ultra320 SCSI features and other new features, such as packetized information transfer (SPI information units), data group transfers, paced transfers, increased CRC protection, etc.

1.1.1.

1Unless required for clarity, “SCSI” is now used instead of “SCSI-3.”

Parallel SCSI Interface Product Manual, Rev. A 1

1.1.1 Scope of SCSI standards

Figure 1 uses a representative set of specifications to show the functional partitions and the relationships among SCSI standards applicable to drives covered by this manual.

SCSI Block

Commands (SBC)

Commands

SCSI Primary

Commands (SPC)

SCSI

Interlocked

Protocol

SCSI Architecture Model (SAM)

Figure 1. Functional scope of SCSI1 standards

and

SCSI

Parallel

Interface (SPI-3)

Physical and Signaling

SCSI

Fibre Channel

Protocol (FCP)

Fibre Channel

Interface (FC-PH)

Protocols

Common Access Method (CAM)

Interconnects

The functional areas define the scope of each standard as follows:

• SCSI Architecture Model: Defines the SCSI systems model, the functional partitioning of the SCSI standard set and requirements applicable to all SCSI implementations and implementation standards.

• Commands: Implementation standards which define classes including a device model for each class. These standards specify the required commands and behavior that is common to all devices or unique to a given class of devices and prescribe the rules to be followed by a SCSI initiator port when sending commands to a device.

• Common Access Method: Implementation standard which defines a host architecture and set of services for device access.

• Protocols: Implementation standards which define the rules for exchanging information so that different SCSI devices can communicate.

• Interconnects: Implementation standards which define the electrical and signaling rules essential for devices to interoperate over a given physical interconnect.

The diagram of Figure 1 shows how the standards listed below fit within each category. The standards included in the diagram are meant to serve as examples and may not reflect the full set of standards currently in force.

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1.1.2 Applicable standards

The following ANSI standards should be referenced for more details about SCSI system standards of operation:

• SCSI Architecture Model - 4 (SAM-4), T10/1683-D

• SCSI Enclosure Services - 2 (SES-2), T10/1559-D

• SCSI Block Commands - 3 (SBC-3), T10/1215-D

• SCSI Primary Commands - 4 (SPC-4), T10/1731-D

• SCSI Enhanced Parallel Interface (EPI), T10/1143-DT

• SCSI Parallel Interface (SPI-5), T10/1525D

• SCSI Medium Changer Commands - 3 (SMC-3), T10/1730-D

• SCSI Controller Command Set - 2 (SCC-2), T10/1225D

• SCSI Stream Command - 3 (SSC-3), T10/1611-D

1.2 General interface description

This Parallel SCSI Interface Manual describes the Seagate Technology LLC. subset of the SCSI (Small Computer Systems Interface) as implemented on the Seagate-built drives. The interface is compatible with the SCSI Interface Specifications listed in Section ligent” peripherals.

The Seagate SCSI interface described herein consists of a 9 or 18 bit bidirectional data bus (includes bits for parity checking and enabling CRC protection), plus 9 control signals. The SCSI interface supports multiple ini tiators, disconnect/reconnect, self-configuring host software, automatic features that relieve the host from the necessity of knowing the physical architecture of the target (logical block addressing is used), and some other miscellaneous features.

1.1.2. The drives covered by this manual are classified as “Intel-

The SCSI physical interface uses either single-ended drivers and receivers or low voltage differential drivers and receivers and uses asynchronous or synchronous communication protocols. The bus interface transfer rate for asynchronous or synchronous is given in individual drive’s Product Manual. The bus protocol supports multiple initiators, disconnect/reconnect, additional messages plus 6-byte, 10-byte, 12-byte, 16-byte and vari able length Command Descriptor Blocks.

Unless specified otherwise in the individual drive’s Product Manual, the drive is always a SCSI target port, and never a SCSI initiator port. For certain commands, which may or may not be supported by a particular drive model, the drive must act as a SCSI initiator port, but does not otherwise do so. For purposes of this specifica tion, “drive” may be substituted for the word “target” wherever “target” appears.

In the event of a conflict between this document and ANSI SCSI documents, the requirements of the ANSI documents shall apply.

Note. In this revision, some new terminology is introduced as taken from the ANSI specifications. In many

instances, the broader scope terms such as “initiator” and “target” are not used, but rather the more specific terms “Application Client” and “Device Server” appear. In Figure “application clients” from a single initiator may have one or more tasks in queue with several “device servers” in a single target. A drive could be a SCSI target port or it could be one of the device servers as part of some larger entity. When reading the description, one needs to be able to put the drive of interest in the proper context in terms of what is shown in Figure operation of the SCSI protocol, the terms in the SCSI architectural model as described in ANSI specification T10/1683-D (SAM-4) should be well understood before reading operation descriptions in any SCSI document. Although a Glossary of terms is provided herein, the definitions may not be adequate for some. The SAM-4 specification gives a more detailed understanding of some of the new SCSI ter minology

2. For a proper understanding of the

2, it can be seen that several

Parallel SCSI Interface Product Manual, Rev. A 3

Application

Client

Device Service Request

Device Service Response

Task Management Request

Task Management Response

Logical

Unit

Device Server

Task

Manager

Initiator

Figure 2. SCSI client-server model

Target

1.2.1 Glossary

aborted command—A SCSI command that has been ended by aborting the task created to execute it.

ACA—Auto Contingent Allegiance (see below).

additional sense code—a combination of the ADDITIONAL SENSE CODE and ADDITONAL SENSE CODE

QUALIFIER in the sense data (see SPC-4)

application client—An object that is the source of SCSI commands. An object in this sense is not a tangible piece of hardware, but may be a single numeric parameter, such as a logical unit number, or a complex entity that performs a set of operations or services on behalf of another object (see ANSI SAM-4, T10/1683-D).

asynchronous event notification—A procedure used by targets to notify initiators of events that occur when a pending task does not exist for that initiator.

asynchronous transfer—An information transfer that uses the REQ/ACK handshake with an offset of zero.

auto contingent allegiance (ACA)—One of the conditions of a task set following the return of a CHECK

CONDITION status. See Section

4.4.2.

blocked task state—The state of a task that is prevented from completing due to an ACA condition.

blocking boundary—A task set boundary denoting a set of conditions that inhibit tasks outside the boundary

from entering the Enabled state.

byte—An 8-bit construct.

call—The act of invoking a procedure.

client-server—A relationship established between a pair of distributed objects where one (the client) requests

the other (the server) to perform some operation or unit of work on the client’s behalf (see SAM-4).

client—An object that requests a service from a server.

command—A request describing a unit of work to be performed by a device server.

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command descriptor block—A structure used to communicate a command from an application client to a device server. Command structures of 6, 10, 12, or 16 bytes are used, but a new variable length command structure has recently been introduced.

completed command—A command that has ended by returning a status and service response of Task Complete or Linked Command Complete.

completed task—A task that has ended by returning a status and service response of Task Complete. The actual events comprising the Task Complete response are protocol specific.

confirmation—A response returned to an object, which signals the completion of a service request.

confirmed service—A service available at the protocol service interface, which requires confirmation of com-

pletion. The confirmed service consists of the request and confirmation steps and optionally the indication and response steps.

contingent allegiance (CA)—An optional condition of a task set following the return of a CHECK CONDITION status. A detailed definition of contingent allegiance may be found in Section SAM-4, ACA supported by SAM-4)

control mode page—The mode page that identifies the settings, and provides control, of several device server behaviors that may be of interest to an application client or may be changed by an application client. The complete definition of the Control mode page is found in the Seagate SCSI Command Reference Manual, Part number 100293068, or SPC-4.

current task—A task that is in the process of sending messages, sending status, transferring data, or transferring command data to or from the initiator.

4.4.2. (CA declared obsolete by

cyclic redundancy check (CRC)—An error detecting code used to detect the validity of data that has been transferred during the current data group.

data field—The portion of a data group that contains data bytes.

data group—A sequence of data bytes and the four pCRC bytes during a DT DATA IN PHASE or a DT DATA

OUT PHASE that starts at the first byte of the DT DATA phase or at the first byte after the last pCRC byte.

data group transfer—Parallel transfers that transfer data and pCRC information using only data groups. The last four bytes of a data group transfer contain CRC information over the whole data group.

destination device—The SCSI device to which a service delivery transaction is addressed. See source device.

device server—An object within the logical unit which executes SCSI tasks according to the rules for task management described in clause 7 of ANSI SAM-4 document, T10/1683-D.

device service request—A request, submitted by an application client, conveying a SCSI command to a device server.

device service response—The response returned to an application client by a device server on completion of a SCSI command.

differential—A signalling alternative that employs differential (two complementary signals) drivers and receivers to improve signal-to-noise ratios and increase maximum cable lengths.

disconnect—The action that occurs when a SCSI device releases control of the SCSI bus, allowing it to go to the BUS FREE PHASE.

domain—An I/O system consisting of a set of SCSI devices that interact with one another by means of a service delivery subsystem.

dormant (task state)—The state of a task that is prevented from starting execution due to the presence of certain other tasks in the task set.

Parallel SCSI Interface Product Manual, Rev. A 5

double transition (DT)—The latching of data on both the assertion edge and the negated edge of the REQ or ACK signals.

driver—The circuitry used to control the state of the bus.

enabled task state—The state of a task that may complete at any time. Alternatively, the state of a task that is

waiting to receive the next command in a series of linked commands.

ended command—A command that has completed or aborted.

exception condition—Any event that causes a SCSI device to enter an auto contingent allegiance or contin-

gent allegiance condition.

faulted initiator—The initiator to which a Command Terminated or CHECK CONDITION status was returned.

faulted I_T nexus: The I_T nexus on which a CHECK CONDITION status was returned that resulted in the

establishment of an ACA. The faulted I_T nexus condition is cleared when the ACA condition is cleared.

faulted task set: A task set that contains a faulting task. The faulted task set condition is cleared when the ACA condition resulting from the CHECK CONDITION status is cleared.

faulting command: A command that completed with a status of CHECK CONDITION that resulted in the establishment of an ACA.

faulting task: A task that has completed with a status of CHECK CONDITION that resulted in the establishment of an ACA.

function complete—A logical unit response indicating that a task management function has finished. The actual events comprising this response are protocol specific.

hard reset—a SCSI target port response to a reset event or a SCSI target port Reset in which the target performs the operations described in Section 7.6.7.

implementation—The physical realization of an object.

implementation-specific—A requirement or feature that is defined in a SCSI standard but whose implemen-

tation may be specified by the system integrator or vendor.

implementation option—An option whose actualization within an implementation is at the discretion of the implementor.

indication—The second step in a four-step confirmed service reply to a request.

information unit transfer—Parallel transfers that transfer data, status, commands, task attributes, task man-

agement information, acrid, and nexus information using only SPI information units.

initial connection—The result of a physical connect. It exists from the assertion of the BSY signal in a SELECTION PHASE until the next BUS FREE PHASE or the next QAS REQUEST message.

initiator—A SCSI device containing application clients which originate device service and task management requests to be processed by a SCSI target port SCSI device.

interconnect—The electrical media (including connectors and passive loads) used to connect the TERMPWR, terminators, and SCSI devices in a SCSI bus.

interconnect subsystem—One or more physical interconnects which appear as a single path for the transfer of information between SCSI devices in a domain.

intersymbol interference (ISI)—The effect of adjacent symbols on the symbol currently being received.

in transit—Information that has been sent to a remote object but not yet received.

6 Parallel SCSI Interface Product Manual, Rev. A

I/O operation—An operation defined by an unlinked SCSI command, a series of linked SCSI commands or a task management function.

I/O process—An I/O process consists of one initial connection or, if information units are enabled, the establishment of a nexus, and a zero or more physical or logical reconnection all pertaining to a single task or a group of tasks. An I/O process begins with the establishment of a nexus. If the SPI information unit transfers are disabled, an I/O process normally ends with a Command Complete message. If information unit transfers are enabled, an I/O process ends with a SPI L_Q information unit with the type field set to status and the Data Length field set to zero.

I_T nexus—A nexus that exists between a SCSI initiator port and a SCSI target port.

I_T_L nexus—A nexus that exists between a SCSI initiator port, a SCSI target port, and a logical unit. This

relationship replaces the prior I T nexus.

I_T_L_Q nexus—A nexus between a SCSI initiator port, a SCSI target port, a logical unit, and a queue tag following the successful receipt of one of the queue tag messages. This relationship replaces the prior I T L nexus.

iuCRC protection—The use of CRC to detect DT DATA PHASE data transmission errors during parallel transfers. Contains CRC information covering all bytes transmitted in a SPI information unit.

layer—A subdivision of the architecture constituted by subsystems of the same rank.

linked CDB—A CDB with the link bit in the control byte set to one.

linked command—One in a series of SCSI commands executed by a single task, which collectively make up

a discrete I/O operation. In such a series, each command has the same task identifier, and all except the last have the link bit in the CDB control byte set to one.

logical connect—Establishes an I_T_L_Q nexus using SPI L_Q information units.

logical disconnect—Reduces the current I_T_L_Q nexus to an I_T nexus.

logical reconnect—Reestablishes an I_T_L_Q nexus from an I_T nexus using SPI L_Q information units.

logical unit—a SCSI target port-resident entity which implements a device model and executes SCSI com-

mands sent by an application client.

logical unit number—A 64-bit identifier for a logical unit.

logical unit option—An option pertaining to a logical unit, whose actualization is at the discretion of the logical

unit implementor.

logical unit reset— A logical unit action in response to a logical unit reset event in which the logical unit performs the operations described in SCSI Architecture Model-4.

lower level protocol—A protocol used to carry the information representing upper level protocol transactions.

mandatory—The referenced item is required to claim compliance with a standard.

media information—Information stored within a SCSI device which is non-volatile (retained through a power

cycle) and accessible to a SCSI initiator port through the execution of SCSI commands.

multidrop—A characteristic of the SCSI bus that allows SCSI devices to be connected to the SCSI bus without disrupting the electrical path between the terminators.

multimode single-ended (MSE)—A signalling alternative for LVD SCSI devices that combines LVD SCSI and single-ended SCSI (see SPI-5, SCSI parallel interface electrical characteristics) drivers and receivers to allow operation when SE SCSI devices are present on the bus.

Parallel SCSI Interface Product Manual, Rev. A 7

nexus—A relationship between a SCSI initiator port and a SCSI target port, logical unit, or queue tag that begins with an initial connection and ends with the completion of the associated I/O process. This relationship is formed as the result of a task.

object—An architectural abstraction or “container” that encapsulates data types, services, or other objects that are related in some way.

odd parity—Odd logical parity, where the parity bit is driven and verified to be that value that makes the number of assertions on the associated data byte plus the parity bit equal to an odd number (1, 3, 5, 7, or 9). See parity bit. If an even number of asserted bits are detected at the receiver, a parity error occurs.

paced transfer—Parallel transfers that transfer information using pacing.

pacing—Use of the ACK or REQ signal as a continuously running clock in combination with the P1 signal to

indicate when data is valid.

packetized—A method of transferring information using SPI information units. See object.

pad field—The portion of a data group that contains pad information.

parallel protocol request—Messages used to negotiate a synchronous data transfer agreement, a wide data

transfer agreement, and set the protocol options between two SCSI devices.

parity bit—A bit associated with a byte that is used to detect the presence of an odd number of asserted bits within the byte. The parity bit is driven such that the number of logical ones in the byte plus the parity bit is odd.

pCRC field—The portion of a data group that contains pCRC information.

pCRC protection—The use of pCRC to detect DT DATA PHASE.

peer-to-peer protocol service—A service used by an upper level protocol implementation to exchange infor-

mation with its peer.

peer entities—Entities within the same (protocol) layer.

pending task—A task that is not a current task.

physical interconnect—A single physical pathway for the transfer of information between SCSI devices in a

domain.

physical reconnect—The act of resuming a nexus to continue a task. A SCSI target port initiates a physical reconnect when conditions are appropriate for the physical bus to transfer data associated with a nexus between a SCSI initiator port and a SCSI target port.

physical reconnection—The result of a physical reconnect that exists from the assertion of the BSY signal in a SELECTION or RESELECTION PHASE. A physical reconnection ends with the BUS FREE PHASE (see Section

port—Synonymous with “service delivery port.” A single attachment to a SCSI bus from a SCSI device.

procedure—An operation that can be invoked through an external calling interface.

protocol—The rules governing the content and exchange of information passed between distributed objects

through the service delivery subsystem.

protocol option—An option whose definition within a SCSI protocol standard is discretionary.

3.1.1) or a QAS REQUEST message (see Section 4.3.13).

protocol service confirmation—A signal from the lower level protocol service layer notifying the upper layer that a protocol service request has completed.

protocol service indication—A signal from the lower level protocol service layer notifying the upper level that a protocol transaction has occurred.

8 Parallel SCSI Interface Product Manual, Rev. A

protocol service request—A call to the lower level protocol service layer to begin a protocol service transaction.

protocol service response—A reply from the upper level protocol layer in response to a protocol service indication.

quick arbitration and selection process (QAS)—Quicker than the normal arbitration and selection process. Implementation is optional for SCSI devices.

queue—The arrangement of tasks within a task set, usually according to the temporal order in which they were created. See task set.

queue tag—The parameter associated with a task that uniquely identifies it from other tagged tasks for a logical unit from the same initiator.

receiver—A client or server that is the recipient of a service delivery transaction.

reference model—A standard model used to specify system requirements in an implementation-independent

manner.

request—A transaction invoking a service.

request-response transaction—An interaction between a pair of distributed, cooperating objects, consisting

of a request for service submitted to an object followed by a response conveying the result.

request-confirmation transaction—An interaction between a pair of cooperating objects, consisting of a request for service submitted to an object followed by a response for the object confirming request completion.

reset event—A protocol-specific event which may trigger a hard reset response from a SCSI device as described in Section

response—A transaction conveying the result of a request.

SCSI application layer (SAL)—The protocols and procedures that implement or invoke SCSI commands and

task management functions by using services provided by a SCSI protocol layer.

SCSI device—A device that contains at least one SCSI port and the means to connect its drivers and receivers to the bus.

SCSI device identifier—An address by which a SCSI device is referenced within a domain.

SCSI I/O system—An I/O system, consisting of two or more SCSI devices, a SCSI interconnect and a SCSI

protocol, which collectively interact to perform SCSI I/O operations.

SCSI protocol layer—The protocol and services used by a SCSI application layer to transport data representing a SCSI application protocol transaction.

sender—A client or server that originates a service delivery transaction.

server—A SCSI object that performs a service on behalf of a client.

service—Any operation or function performed by a SCSI object, which can be invoked by other SCSI objects.

service delivery failure—Any non-recoverable error causing the corruption or loss of one or more service

delivery transactions while in transit.

5.3.

service delivery port—A device-resident interface used by the application client, device server or task manager to enter and retrieve requests and responses from the service delivery subsystem. Synonymous with “port.”

service delivery subsystem—That part of a SCSI I/O system which transmits service requests to a logical unit or target and returns logical unit or target responses to a SCSI initiator port.

Parallel SCSI Interface Product Manual, Rev. A 9

service delivery transaction—A request or response sent through the service delivery subsystem.

signal—(n) A detectable asynchronous event possibly accompanied by descriptive data and parameters. (v)

The act of generating such an event.

single transition (ST)—The latching of data only on the assertion edge of the REQ or ACK signals.

source device—The SCSI device from which a service delivery transaction originates. See destination device.

SPI information unit—Data structures that encapsulate data, status, command, task attributes, iuCRC, and

nexus information into various formats.

SPI L_Q information unit—The SPI L_Q information unit (see Section 6.2.2, tables 49 and 50) contains L_Q nexus (Logical unit—Q tag relationship) information for the information unit that follows, the type of information unit that follows, and the length of information unit that follows. A SPI L_Q information unit shall precede all SPI command information units, SPI multiple command information units, SPI data information units, SPI status information units, and the first of an uninterrupted sequence of SPI data stream information units.

subsystem—An element in a hierarchically partitioned system which interacts directly only with elements in the next higher division or the next lower division of that system.

suspended information—Information stored within a logical unit that is not available to any pending tasks.

target—A SCSI device which receives SCSI commands and directs such commands to one or more logical

units for execution.

task—An object within the logical unit representing the work associated with a command or group of linked commands. A task consists of one initial connection and zero or more physical or logical reconnections, all per taining to the task.

task abort event—An event or condition indicating that the task has been aborted by means of a task management function.

task address—a SCSI initiator port identifies a task to a SCSI target port using a Task Address. The Task Address object represents either a Tagged Task Address or an Untagged Task Address without regard for the tagged or untagged nature of the Task. A Tagged Task Address is composed of a Logical Unit Identifier and a Tag. An Untagged Task Address is composed of a Logical Unit Identifier.

task completion event—An event or condition indicating that the task has ended with a service response of Task Complete.

task ended event—An event or condition indicating that the task has completed or aborted.

task management function—A task manager service which can be invoked by an application client to affect

the execution of one or more tasks.

task management request—A request submitted by an application client, invoking a task management func- tion to be executed by a task manager.

task management response—The response returned to an application client by a task manager on completion of a task management request.

task manager—A server within the target which executes task management functions.

task set—A group of tasks within a SCSI target port device, whose interaction is dependent on the queuing

and auto contingent allegiance rules of Section

task slot—Resources within the logical unit that may be used to contain a task.

7.6.1.

task tags—A Tag is a field containing up to 64 bits that is a component of a Tagged Task Identifier. A SCSI initiator port assigns tag values in each Tagged Task Identifier in a way that ensures that the identifier uniqueness requirements stated in ANSI SAM-4, T10/1683-D, are met.

10 Parallel SCSI Interface Product Manual, Rev. A

third-party command—A SCSI command which requires a logical unit within the target device to assume the initiator role and send a SCSI command to a SCSI target port device.

transaction—A cooperative interaction between two objects, involving the exchange of information or the execution of some service by one object on behalf of the other.

transfer period—The negotiated time between edges of REQ or ACK that latch data. For ST, the transfer period is measured from assertion edge of the REQ or ACK signal to the next assertion edge of the signal. For DT, the transfer period is measured from a transition edge of the REQ or ACK signal to the next transition edge of the signal.

unconfirmed protocol service—A service available at the protocol service interface, which does not result in a completion confirmation.

unlinked command—A SCSI command having the link bit set to zero in the CDB control byte.

upper level protocol—An application-specific protocol executed through services provided by a lower level

protocol.

1.2.2 Keywords

Several keywords are used to differentiate between different levels of requirements and optionality, as follows:

vendor-specific—Specification of the referenced item is determined by the device vendor.

protocol-specific—Implementation of the referenced item is defined by a SCSI protocol standard (see Sec-

tion 1.1.1.)

expected—A keyword used to describe the behavior of the models specified by this standard.

invalid—A keyword used to describe an illegal or unsupported bit, byte, word, field, or code value. Receipt of

an invalid bit, byte, word, field, or code value shall be reported as an error.

mandatory—A keyword indicating items required to be implemented as defined by this standard.

may—A keyword that indicates flexibility of choice with no implied preference (equivalent to “may or may not”).

may not—Keywords that indicates flexibility of choice with no implied preference (equivalent to “may or may

not”).

obsolete—A keyword indicating items that were defined in prior SCSI standards but have been removed from this standard.

option, optional—Keywords that describe features which are not required to be implemented by this standard. However, if any optional feature defined by the standard is implemented, it shall be implemented as defined by the standard.

reserved—A key word referring to bits, bytes, words, fields, and code values that are set aside for future standardization. Their use and interpretation may be specified by future extensions to this or other standards. A reserved bit, byte, word, or field shall be set to zero, or in accordance with a future extension to this standard. Recipients are not required to check reserved bits, bytes, words, or fields for zero values. Receipt of reserved code values in defined fields shall be treated as an error.

shall—A keyword indicating a mandatory requirement. Designers are required to implement all such mandatory requirements to ensure interoperability with other standard conformant products.

should—A keyword indicating flexibility of choice with a strongly preferred alternative. Equivalent to the phrase “it is recommended.”

Parallel SCSI Interface Product Manual, Rev. A 11

1.3 Physical interface characteristics

The physical interface characteristics (cables, connectors, electrical descriptions, termination requirements, etc.) for the drives covered by this Interface Manual are found in each individual drive’s Product Manual, since these features are not the same for all drives.

1.4 Summary of SCSI messages

Following is an alphabetical summary of the SCSI messages described in this manual. Details are given in Section

Message Name Hex Code Page number

ABORT TASK 06 105 CLEAR QUEUE 0E 106 DISCONNECT 04 87 EXTENDED MESSAGE 01 84 IDENTIFY 80-FF 87 IGNORE WIDE RESIDUE 23 88 INITIATE RECOVERY 0F Not described in this manual INITIATOR DETECTED ERROR 05 89 MESSAGE PARITY ERROR 09 89 MESSAGE REJECT 07 89 MODIFY DATA POINTER 01, 05, 00 89 (extended message) NO OPERATION 08 91 PARALLEL PROTOCOL REQUEST 01, 06, 04 92 QAS REQUEST 55 96 RELEASE RECOVERY 10 Not described in this manual RESTORE POINTERS 03 96 SAVE DATA POINTERS 02 96 SYNCHRONOUS DATA TRANSFER REQUEST 01, 03, 01 97 (extended message) TASK ATTRIBUTE MESSAGES 102 ACA (AUTO CONTINGENT

ALLEGIANCE) HEAD OF QUEUE TAG 21 104 LINKED COMMAND COMPLETE 0A 89 ORDERED QUEUE TAG 22 104 SIMPLE QUEUE TAG 20 104 TASK COMPLETE 00 99 TASK MANAGEMENT MESSAGES 105 ABORT TASK 00 105 ABORT TASK SET 06 106 CLEAR ACA 16 106 CLEAR TASK SET 0E 106 LOGICAL UNIT RESET 17 106 TARGET RESET 0C 106 WIDE DATA TRANSFER REQUEST 01, 03 100 (extended message)

24 103

12 Parallel SCSI Interface Product Manual, Rev. A

2.0 SCSI bus

This manual discusses only the “logical” and timing characteristics of the SCSI system and interface. A general description of the SCSI bus physical characteristics (voltages, connector configurations, pinouts, etc.) are given in the individual drive’s Product Manual, in the “Interface requirements” section, which covers the inter face requirements and SCSI features supported by the drive described in the particular Product Manual being referenced. For all of the physical details of the SCSI interface, consult the ANSI standards referenced in Sec tion 1.1.2.

Communication on the SCSI Bus is allowed between only two SCSI devices at a time. Seagate drives support systems with a maximum of 16 SCSI devices including the host computer(s) connected to the SCSI bus. Each SCSI device has a SCSI ID bit assigned as shown in Table plugs onto a connector in a binary coded configuration during system configuration. Some drive models have an interface that includes the SCSI bus ID lines, so that the host can set the drive ID over the interface (see individual drive’s Product Manual, “Option/configuration headers” section).

When two SCSI devices communicate on the SCSI Bus, one acts as a SCSI initiator port and the other acts as a SCSI target port. The initiator (typically a host computer) originates an I/O process and the target performs whatever operations/tasks are called for by the I/O process. Devices arbitrate to get control of the bus to per form whatever communications are required by the current I/O process. As part of the arbitration process, devices on the SCSI bus assert their bus ID (one of the DB lines as shown in Table is discussed in more detail later. Devices supported by this interface specification always operate as targets, unless otherwise specified (i.e., if certain commands are supported) in the individual drive’s Product Manual, Volume 1.

1. The SCSI ID is assigned by installing 0-3 jumper

1). The arbitration process

Parallel SCSI Interface Product Manual, Rev. A ) 13

Table 1: SCSI IDs and associated SCSI bus arbitration priorities

SCSI

addressDB15

7 - - - - - - - - 1 - - - - - - - 1

6 - - - - - - - - - 1 - - - - - - 2

5 - - - - - - - - - - 1 - - - - - 3

4 - - - - - - - - - - - 1 - - - - 4

3 - - - - - - - - - - - - 1 - - - 5

2 - - - - - - - - - - - - - 1 - - 6

1 - - - - - - - - - - - - - - 1 - 7

0 - - - - - - - - - - - - - - - 1 8

15 1 - - - - - - - - - - - - - - - 9

14 - 1 - - - - - - - - - - - - - - 10

13 - - 1 - - - - - - - - - - - - - 11

12 - - - 1 - - - - - - - - - - - - 12

11 - - - - 1 - - - - - - - - - - - 13

10 - - - - - 1 - - - - - - - - - - 14

DB8DB

Priority

9 - - - - - - 1 - - - - - - - - - 15

8 - - - - - - - 1 - - - - - - - - 16

Key: - = a logical 0 bit resulting from the data bus bit being released

The Host Adapter/Initiator must be identified by one of the 16 SCSI Device IDs (usually 7, which is highest arbitration priority). Make sure that none of the devices on the SCSI bus have duplicate IDs.

Certain SCSI bus functions are assigned to the initiator and certain SCSI bus functions are assigned to the target. The initiator will select a particular target. The target will request the transfer of Command, Data, Status, or other information on the data bus.

Under SCSI-2 protocol, information transfers on the data bus are interlocked and follow a defined REQ/ACK Handshake protocol. One byte of information will be transferred with each handshake. Synchronous data transfers do not require a one-for-one interlocking of REQ/ACK signals, but the total number of REQ pulses in a particular data transfer event must equal the total number of ACK pulses. The synchronous data transfer option is described in Paragraphs 3.1.5.2 and 3.5.3.2 of the Ultra2 SCSI Interface Manual, part number

77738479.

This Ultra160/Ultra320 Parallel SCSI Interface Manual, discusses SCSI-3 protocol (now called only “SCSI”). There are now different ways of latching data from the REQ and ACK signals, depending on whether ST DATA phases, DT DATA phases, or paced transfers are being used for information transfers. This is described in Section

2.1.2.

The drive supports single initiator, single target; single initiator, multiple target; multiple initiator, single target; or multiple initiator, multiple target bus configurations.

14 Parallel SCSI Interface Product Manual, Rev. A )

2.1 SCSI bus signals overview

Information transfer on the SCSI bus is allowed between only two SCSI devices at any given time except during MESSAGE IN PHASE when QAS is enabled. All SCSI devices that have QAS enabled are required to monitor messages during a MESSAGE IN PHASE for a QAS REQUEST MESSAGE. The maximum number of SCSI devices is determined by the width of the data path implemented. The SCSI devices may be any combi nation of SCSI initiator ports (commonly called “initiators”) and SCSI target ports (commonly called “targets”), provided there is at least one of each.

Each SCSI device has a SCSI address and a corresponding SCSI ID bit assigned to it. When two SCSI devices communicate on the SCSI bus, one acts as the initiator and the other acts as the target. The initiator originates an I/O process and the target receives the I/O process.

Some drive models have a single 80-pin I/O connector that contains additional interface lines that carry drive configuration select signals. These are peculiar to certain drives and are not SCSI standard signals. These are described in the individual drive’s product manual, Volume 1.

The 28 SCSI standard signals are described as follows:

BSY (Busy)—An “OR-tied” signal to indicate the bus is being used.

SEL (Select)—An “OR-tied” signal used by a SCSI initiator port to select a SCSI target port, or by a SCSI tar-

get port to reselect a SCSI initiator port.

RST (Reset)—An “OR-tied” signal that indicates the bus reset condition (see Section 5.2).

C/D (Control/Data)—A signal sourced by a SCSI target port that indicates whether CONTROL or DATA

PHASE information is on the data bus. Assertion indicates Control (i.e., COMMAND, STATUS, and MESSAGE phases).

I/O (Input/Output)—A signal sourced by a SCSI target port to control the direction of data movement on the Data Bus with respect to a SCSI initiator port. Assertion indicates input to the initiator. This signal also distin guishes between SELECTION and RESELECTION phases.

MSG (Message)—A signal sourced by a SCSI target port to indicate the MESSAGE phase or a DT DATA phase depending on whether C/D is true or false. Asserted indicates MESSAGE or DT DATA.

REQ (Request)—A signal sourced by a SCSI target port to indicate a request for an information transfer on the SCSI bus.

ACK (Acknowledge)—A signal sourced by a SCSI initiator port to respond with an acknowledgment of an information transfer on the SCSI bus.

ATN (Attention)—A signal sourced by a SCSI initiator port to indicate the Attention condition.

DIFFSENS (Differential Sense)/Multimode—SE or LVD alternative— “LW” and “LC” models have I/O cir-

cuits that can operate either in single-ended (SE) or low voltage differential (LVD) mode. When the interface DIFFSENS line is between -0.35 V and +0.5 V, the drive interface circuits operate single-ended. When DIFFS ENS is between +0.7 V and +1.9 V, the drive interface circuits operate low voltage differential. This arrangement is not intended to allow dynamically changing transmission modes, but rather to prevent incompatible devices from attempting to interoperate. Drives must operate only in the mode for which the installation and interface cabling is designed. Multimode I/O circuits used by “LW” and “LC” devices do not operate at high volt age differential levels and should never be exposed to high voltage differential environments unless the command mode voltages in the environment are controlled to safe levels for single-ended and low voltage differential devices (see the ANSI SPI-5 specification). High Voltage Differential (HVD) is now an obsolete ANSI standard.

P_CRCA (Parity/CRC Available)—A signal identifying either parity or CRC available based on bus phase and negotiated settings.

Parallel SCSI Interface Product Manual, Rev. A ) 15

During the SELECTION PHASE, RESELECTION PHASE, ST DATA PHASE, COMMAND PHASE, MESSAGE PHASE, and STATUS PHASE, this signal is referred to as DB(P_CRCA) and is sourced by the SCSI device port driving the Data Bus. The DB(P_CRCA) signal is associated with the DB(7-0) signals and is used to detect the presence of an odd number of bit errors within the byte. The DB(P_CRCA) bit is driven such that the num ber of logical ones in the byte plus the parity bit is odd.

Data group transfers are enabled (see Section 4.3.12) when this signal is referred to as P_CRCA and is sourced by the target to control whether a data group field is a pad field, pCRC field, or data field (see Section

2.11.1). When asserted, the data group field shall be pad or pCRC fields that shall not be transferred to the application client. When negated, the data group field shall be a data field that shall be transferred to the application client.

During DT DATA phases when information unit transfers are enabled, this signal is referred to as P_CRCA and sourced by the SCSI target. Depending on the negotiated condition of read streaming and write flow control, the SCSI initiator and target usage for P_CRCA is different. When information unit transfers are enabled, the SCSI target and initiator shall use the P_CRCA signal as indicated in Table

Table 2: P_CRC signal usage requirements

SCSI initiator Write flow control

Disabled Disabled All Ignore Continuously negated.

Enabled Disabled DT DATA IN Ignore Continuously negated.

Read streaming DT Data phase

response to

P_CRCA

SCSI target usage of P_CRCA

DT DATA OUT Monitor Asserts to indicate when the current SPI data stream

information unit is the last SPI data stream information unit of the current write stream.

Disabled Enabled DT DATA IN Monitor Asserts to indicate when the current SPI data stream

information unit is the last SPI data stream information unit of the current read stream.

DT DATA OUT Ignore Continuously negated.

Enabled Enabled DT DATA IN Monitor Asserts to indicate when the current SPI data stream

information unit is the last SPI data stream information unit of the current read stream.

DT DATA OUT Monitor Asserts to indicate when the current SPI data stream

information unit is the last SPI data stream information unit of the current read stream.

A SCSI device is not required to use read streaming even if it is enabled A SCSI device is not required to use write flow control even if it is enabled

P1 (Parity 1)—A signal normally sourced by the SCSI device driving the Data Bus. The P1 signal is associated with the DB(15–8) signals and is used to detect the presence of an odd number of bit errors within the byte The P1 bit is driven such that the number of logical ones in the byte plus the P1 bit is odd.

During the ST DATA PHASE with transfer length set for 8-bit transfers, COMMAND PHASE, MESSAGE PHASE, and STATUS phase, the P1 signal shall not be driven by any SCSI device.

During the SELECTION phase and the RESELECTION phase on a 16-bit wide bus segment the P1 signal shall be sourced by the SCSI device driving the DATA BUS.

When data group transfers are enabled (see Section 4.3.12), the P1 signal shall be continuously negated by the SCSI device driving the DB(15-0) signals and shall be ignored by the SCSI device receiving the DB(15-0) signals during DT DATA phases.

16 Parallel SCSI Interface Product Manual, Rev. A )

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