1、ANSI INCITS 131-1994 (R1999)(formerly ANSI X3.131-1994 (R1999)for Information Systems -Small Computer SystemInterface-2ANSI x3.131-1994 American National Standard for Information Systems - Small Computer System Interface-2 Secretariat Computer and Business Equipment Manufacturers Association Approve
2、d January 31,1994 American National Standards Institute, Inc. Abstract The SCSI protocol is designed to provide an efficient peer-to-peer I/O bus with up to 16 devices, including one or more hosts. Data may be transferred asynchronously at rates that only depend on device implementation and cable le
3、ngth. Synchronous data transfers are supported at rates up to 10 mega-transfers per second. With the 32-bit wide data transfer option, data rates of up to 40 megabytes per second are possible. SCSI-2 includes command sets for magnetic and optical disks, tapes, printers, processors, CD- ROMs, scanner
4、s, medium changers, and communications devices. AmericanNationalStandardApproval of an American National Standard requires review by ANSI that therequirements for due process, consensus, and other criteria for approval havebeen met by the standards developer.Consensus is established when, in the jud
5、gment of the ANSI Board of StandardsReview, substantial agreement has been reached by directly and materiallyaffected interests. Substantial agreement means much more than a simplemajority, but not necessarily unanimity. Consensus requires that all views andobjections be considered, and that a conce
6、rted effort be made toward theirresolution.The use of American National Standards is completely voluntary; their existencedoes not in any respect preclude anyone, whether he has approved the standardsor not, from manufacturing, marketing, purchasing, or using products, processes,or procedures not co
7、nforming to the standards.The American National Standards Institute does not develop standards and will inno circumstances give an interpretation of any American National Standard.Moreover, no person shall have the right or authority to issue an interpretation ofan American National Standard in the
8、name of the American National StandardsInstitute. Requests for interpretations should be addressed to the secretariat orsponsor whose name appears on the title page of this standard.CAUTION NOTICE: This American National Standard may be revised orwithdrawn at any time. The procedures of the American
9、 National StandardsInstitute require that action be taken periodically to reaffirm, revise, or withdrawthis standard. Purchasers of American National Standards may receive currentinformation on all standards by calling or writing the American National StandardsInstitute.CAUTION: The developers of th
10、is standard have requested that holders of patents that may be required for theimplementation of the standard disclose such patents to the publisher. However, neither the developers nor the publisherhave undertaken a patent search in order to identify which, if any, patents may apply to this standar
11、d. As of the date ofpublication of this standard and following calls for the identification of patents that may be required for the implementationof the standard, no such claims have been made. No further patent search is conducted by the developer or publisher inrespect to any standard it processes
12、. No representation is made or implied that licenses are not required to avoidinfringement in the use of this standard.Published byAmerican National Standards Institute11 West 42nd Street, New York, New York 10036Copyright 1994 by Information Technology Industry Council (ITI)All rights reserved.No p
13、art of this publication may be reproduced in anyform, in an electronic retrieval system or otherwise,without prior written permission of ITI, 1250 Eye Street NW,Washington, DC 20005.Printed in the United States of AmericaContents Page Foreword . . . . . . . . . . . . . . . . . . . . . . . . . . . .
14、. . . . . . . . . . . . . . . . . . . . xix Introduction . , , . . . . . . . . . . . . . , . . , . . . . . . . . . . . . . . . . . , . . . , . . . . . xxii 1 Scope 1 2 Normative references . 2 3 Definitions, symbols and abbreviations 3 3.1 Definitions . 3 3.2 Symbols and abbreviations 5 4 General .
15、6 4.1 Overview 6 4.2 Conventions . 7 5 5.1 5.2 5.2.1 5.2.2 5.2.3 5.3 5.3.1 5.3.1.1 5.3.1.2 5.3.1.3 5.3.2 5.3.2.1 5.3.2.2 5.3.2.3 5.3.3 5.4 5.4.1 5.4.1.1 5.4.1.2 5.4.2 5.4.2.1 5.4.2.2 5.4.3 5.4.4 5.5 5.6 5.6.1 5.6.2 5.6.3 5.7 5.7.1 5.7.2 5.7.3 5.7.4 5.7.5 Physical characteristics . Physical descripti
16、on Cable requirements . Single-ended cable Differential cable Cable requirements for fast synchronous data transfer Connector requirements Non-shielded connector requirements Non-shielded connector alternative l- A cable Non-shielded connector alternative 2- A cable Non-shielded connector - B cable
17、. Shielded connector requirements Shielded connector alternative l- A cable Shielded connector alternative 2- A cable Shielded connector - B cable . Connector contact assignments . Electrical description . Single-ended alternative . Output characteristics Input characteristics Differential alternati
18、ve . Output characteristics Input characteristics Terminator power RESERVED lines SCSlbus SCSI bus signals Signal values . OR-tied signals . Signal sources SCSI bus timing . Arbitration delay Assertion period Bus clear delay . Bus free delay . Bus set delay 8 8 8 8 9 9 9 9 9 10 10 15 15 15 15 20 25
19、25 25 25 26 26 26 26 29 30 32 33 33 33 34 35 35 35 35 36 i 5.7.6 5.7.7 5.7.6 5.7.9 5.7.10 5.7.11 5.7.12 5.7.13 5.7.14 5.7.15 5.7.16 5.7.17 5.7.16 5.6 5.6.1 5.6.2 5.6.3 5.6.4 5.8.5 6 Logical characteristics 39 6.1 SCSI bus phases 39 6.1 .l BUS FREE phase . 39 6.1.2 ARBITRATION phase . 40 6.1.3 SELECT
20、ION phase 40 6.1.3.1 SELECTION time-out procedure . 41 6.1.4 RESELECTION phase 41 6.1.4.1 RESELECTION 41 6.1.4.2 RESELECTION time-out procedure 42 6.1.5 Information transfer phases 42 6.1.5.1 Asynchronous information transfer . 43 6.1.5.2 Synchronous data transfer . 43 6.1.5.3 Wide data transfer . 4
21、4 6.1.6 COMMAND phase . 46 6.1.7 Data phase 46 6.1.7.1 DATAINphase . 46 6.1.7.2 DATAOUTphase . 46 6.1.8 STATUS phase . 46 6.1.9 Message phase . 46 6.1.9.1 MESSAGE IN phase . 46 6.1.9.2 MESSAGE OUT phase . : 46 6.1.10 Signal restrictions between phases 47 6.2 SCSlbus conditions . 47 6.2.1 Attention c
22、ondition . 47 6.2.2 Reset condition . 46 6.2.2.1 Hard reset alternative . 49 6.2.2.2 Soft reset alternative . 49 6.3 SCSlbus phase sequences 50 6.4 SCSI pointers 51 6.5 Message system description . 52 6.6 Messages . 55 6.6.1 ABORT . 55 6.6.2 ABORTTAG . 55 6.6.3 BUS DEVICE RESET . 56 Page Bus settled
23、elay 36 Cable skew delay . 36 Data release delay 36 Deskewdelay 36 Disconnection delay . 36 Hold time . 36 Negation period 36 Power-on to selection time 36 Reset to selection time . 36 Reset hold time 37 Selection abort time . 37 Selection time-out delay 37 Transfer period . 37 Fast synchronous tran
24、sfer option 37 Fast assertion period 37 Fast cable skew delay . 37 Fast deskew delay 37 Fast hold time . 37 Fast negation period . 38 ii 6.6.4 6.6.5 6.6.6 6.6.7 6.6.6 6.6.9 6.6.10 6.6.11 6.6.12 6.6.13 6.6.14 6.6.15 6.6.16 6.6.17 6.6.17.1 6.6.17.2 6.6.17.3 6.6.16 6.6.19 6.6.20 6.6.21 6.6.22 6.6.23 7
25、SCSI commands and status 67 7.1 Command implementation requirements 67 7.1.1 Reserved 67 7.1.2 Operation code types 67 7.2 Command descriptor block 88 7.2.1 Operation code . 69 7.2.2 Logicalunitnumber 70 7.2.3 Logical block address 70 7.2.4 Transfer length . 70 7.2.5 Parameter list length . 70 7.2.6
26、 Allocation length 70 7.2.7 Control field 71 7.3 Status 71 7.4 Command examples . 73 7.4.1 Single command example . 73 7.4.2 Disconnect example 73 7.4.3 Linked command example . 74 7.5 Command processing considerations and exception conditions 74 7.5.1 Programmable operating definition . 74 7.5.2 In
27、correct initiator connection . 75 7.5.3 Selection of an invalid logical unit . 75 7.5.4 Parameter rounding 78 7.5.5 Asynchronous event notification 76 7.5.6 Unexpected reselection . 77 7.6 Contingent allegiance condition . 78 7.7 Extended contingent allegiance condition 78 7.6 Queued I/O processes 7
28、9 7.6.1 Untagged queuing . 79 7.6.2 Tagged queuing 79 7.6.3 Example of queued I/O process . 80 Page CLEAR QUEUE . 56 COMMAND COMPLETE . 56 DISCONNECT 56 IDENTIFY 57 IGNORE WIDE RESIDUE 58 INITIATE RECOVERY . 58 INITIATOR DETECTED ERROR . 59 LINKED COMMAND COMPLETE 59 LINKED COMMAND COMPLETE (WITH FL
29、AG) 59 MESSAGE PARITY ERROR 59 MESSAGEREJECT 59 MODIFY DATA POINTER Message . 60 NO OPERATION 60 Queue tag messages . 60 HEAD OF QUEUE TAG . 61 ORDERED QUEUE TAG . 61 SIMPLE QUEUE TAG . 61 RELEASERECOVERY 61 RESTORE POINTERS 61 SAVEDATAPOINTER 62 SYNCHRONOUS DATA TRANSFER REQUEST 62 TERMINATE I/O PR
30、OCESS 84 WIDE DATA TRANSFER REQUEST 64 . . . III 7.8.3.1 7.8.3.2 7.9 8 8.1 8.1.1 8.1.1.1 8.1.1.2 8.1.1.3 8.1.2 8.1.2.1 8.1.2.2 8.1.2.3 8.1.2.4 8.2 8.2.1 8.2.2 8.2.3 8.2.3.1 8.2.3.2 8.2.3.3 8.2.3.4 8.2.3.5 8.2.3.8 8.2.3.7 8.2.4 8.2.5 8.2.5.1 8.2.5.2 8.2.8 8.2.7 8.2.8 8.2.9 8.2.10 8.2.10.1 8.2.10.2 8.
31、2.10.3 8.2.10.4 8.2.10.5 8.2.11 8.2.12 8.2.12.1 8.2.12.2 8.2.12.3 8.2.12.4 8.2.13 8.2.14 8.2.14.1 8.2.14.2 8.2.14.3 8.2.15 8.2.16 8.2.17 Page Typical sequences for tagged queuing 81 Example of tagged queuing 81 Unit attention condition . 83 All device types 84 Model for all device types . 84 SCSI ad
32、dresses . 84 SCSI device address . 84 Logical units . 84 Target routines . 84 Commands implemented by all SCSI devices 84 Using the INQUIRY command 85 Using the REQUEST SENSE command . 85 Using the SEND DIAGNOSTIC command 85 Using the TEST UNIT READY command 85 Commands for all device types . 85 CHA
33、NGE DEFINITION command 86 COMPARE command . 88 COPYcommand 89 Errors detected by the managing SCSI device 90 Errors detected by a target 91 COPY function code OOh and Olh . 91 COPY function code 02h 92 COPY function code 03h 93 COPY function code 04h 94 Copies with unequal block lengths . 94 COPY AN
34、D VERIFY command 95 INQUIRY command 96 Standard INQUIRY data . 97 Vital product data . 100 LOG SELECT command 101 LOG SENSE command . 103 MODE SELECT(G) command . 104 MODE SELECT(lO) command 106 MODE SENSE(G) command 106 Current values 107 Changeablevalues 10 8 Default values 108 Savedvalues . 108 I
35、nitial responses . 108 MODE SENSE(l0) command . 109 READ BUFFER command . 109 Combined header and data mode (OOOb) 110 Vendor-specific mode (001 b) . 110 Data mode (OlOb) . 110 Descriptor mode (Ollb) . 111 RECEIVE DIAGNOSTIC RESULTS command . 112 REQUEST SENSE command . 112 Sense-keyspecific . 116 D
36、eferred errors . 1 I 7 Sensekeyandsensecodedefinitions 119 SEND DIAGNOSTIC command 125 TEST UNIT READY command 126 WRITE BUFFER command . 127 iv 8.2.17.1 8.2.17.2 8.2.17.3 8.2.17.4 8.2.17.5 8.3 8.3.1 8.3.1.1 8.3.2 8.3.2.1 8.3.2.2 8.3.2.3 8.3.2.4 8.3.2.5 8.3.3 8.3.3.1 8.3.3.2 8.3.3.3 8.3.4 8.3.4.1 8.
37、3.4.2 8.3.4.3 8.3.4.4 8.3.4.5 9 9.1 9.1.1 9.1.2 9.1.3 9.1.4 9.1.5 9.1.8 9.1.7 9.1.8 9.1.9 9.1.10 9.1.11 9.1.12 9.1.13 9.1.13.1 9.1.13.2 9.1.13.3 9.2 9.2.1 9.2.1.1 9.2.1.2 9.2.2 9.2.3 9.2.4 9.2.5 9.2.8 9.2.7 9.2.8 Page Combined header and data mode (OOOb) 128 Vendor-specific mode (001 b) . 128 Data m
38、ode (OlOb) . 128 Download microcode mode (1 OOb) 129 Download microcode and save mode (101 b) . 129 Parameters for ail device types . 129 Diagnostic parameters . 129 Supported diagnostic pages . 130 Log parameters . 131 Buffer over-run/under-run page . 134 Error counter pages 135 Last n error events
39、 page 136 Non-medium error page 136 Supported log pages . 136 Mode parameters . 137 Controimodepage 14 0 Disconnect-reconnect page 142 Peripheral device page . 144 Vital product data parameters 144 ASCII implemented operating definition page . 145 ASCII information page . 145 implemented operating d
40、efinition page . 146 Supported vital product data pages 148 Unit serial number page . 149 Direct-access devices 150 Direct-access device model 150 Removable medium 150 Logical blocks 150 Ready state 151 initialization 151 Medium defects . 151 Datacache I5 2 Reservations . 153 Seekandrezero 15 4 Notc
41、hed drives . 154 Rotational position locking . 154 Relative addressing 154 Errorreporting 15 4 Examples . 15 5 Rotating media . 155 Sequential media 156 Memory media 156 Commands for direct-access devices. 157 FORMAT UNIT command 158 Defect list formats . 162 initialization pattern option . 163 LOCK
42、 UNLOCK CACHE command . 165 PRE-FETCH command 166 PREVENT ALLOW MEDIUM REMOVAL command . 167 READ(G) command 168 READ(l0) command . 168 READ CAPACITY command 169 READ DEFECT DATA command . 171 V 9.2.9 9.2.10 9.2.11 9.2.11.1 9.2.11.2 9.2.11.3 9.2.12 9.2.12.1 9.2.12.2 9.2.12.3 9.2.12.4 9.2.13 9.2.14 9
43、.2.14.1 9.2.14.2 9.2.14.3 9.2.15 9.2.16 9.2.17 9.2.16 9.2.19 9.2.20 9.2.21 9.2.22 9.2.23 9.2.24 9.3 9.3.1 9.3.1.1 9.3.1.2 9.3.2 9.3.3 9.3.3.1 9.3.3.2 9.3.3.3 9.3.3.4 9.3.3.5 9.3.3.6 9.3.3.7 9.3.3.6 9.4 10 10.1 10.1.1 10.1.2 10.1.3 10.1.4 10.1.5 10.1.6 10.1.7 10.1.6 10.2 10.2.1 vi Page READ LONG comm
44、and . 173 REASSIGN BLOCKS command . 174 RELEASEcommand . I7 5 Logical unit release 176 Extent release 176 Third-party release . 176 RESERVEcommand . I7 7 Logical unit reservation . 177 Extent reservation . 177 Third-party reservation . 179 Superseding reservations 160 REZERO UNIT command 180 SEARCH
45、DATA commands 181 SEARCH DATA EQUAL command . 183 SEARCHDATAHlGHcommand . 183 SEARCH DATA LOW command . 183 SEEK(G) and SEEK(lO) commands 183 SET LIMITS command 184 START STOP UNIT command 185 SYNCHRONIZE CACHE command . 188 VERIFYcommand . I8 7 WRITE(G) command 188 WRITE(lO)command.18 8 WRlTEANDVER
46、lFYcommand . 189 WRITE LONG command 190 WRITE SAME command 191 Parameters for direct-access devices . 192 Diagnostic parameters 192 Translate address page - SEND DIAGNOSTIC 192 Translate address page - RECEIVE DIAGNOSTIC . 193 Log parameters . 194 Mode parameters . 194 Caching page 196 Flexible disk
47、 page . 199 Format device page 202 Medium types supported page . 205 Notch and partition page 206 Read-write error recovery page . 207 Rigid disk drive geometry page . 214 Verify error recovery page . 215 Definitions specific to direct-access devices 217 Sequential-access devices . 218 Sequential-ac
48、cess device model 218 Physical elements . 218 Data storage characteristics 219 Partitions within a volume. . 221 Logical elements within a partition . 222 Data buffering 223 Recorded object descriptors (block identifiers) 224 Direction and position definitions 224 Error reporting 225 Command descrip
49、tions for sequential-access devices 226 ERASE command . 227 10.22 10.2.3 10.2.4 10.2.5 10.2.6 10.2.7 10.2.6 10.2.9 10.2.9.1 10.2.10 10.2.10.1 10.2.10.2 10.2.11 10.2.12 10.2.13 10.2.14 10.2.15 10.3 10.3.1 10.3.2 10.3.3 10.3.3.1 10.3.3.2 10.3.3.3 10.3.3.4 10.4 11 Commands for printer devices 257 11.1 Model for printer devices . 257 11.2 Commands for printer devices 256 11.2.1 FORMATcommand 259 11.2.2 PRINTcommand 260 11.2.3 RECOVER BUFFERED DATA command . 260 11.2.4 SLEW AND PRINT command . 261 11.2.5 STOP PRINT command . 262 11.2.6 SYNCHRONIZE BUFFER command 262 11.3 Parameters for printer
