ISO/IEC 14776-323:2017

Information technology - Small computer system interface (SCSI) - Part 323: SCSI Block commands - 3 (SBC-3)

ISO/IEC 14776-323:2017, defines the model and command set extensions to be used in conjunction with the SCSI Primary Command Set standard - 4 (SPC-4) to facilitate operation of SCSI direct-access block devices (e.g. hard disk drives).

Technologies de l'information — Interface de petit ordinateur (SCSI) — Partie 323: Titre manque

General Information

• Status: Published
• Publication Date: 30-Jan-2017
• ICS: 35.200 - Interface and interconnection equipment
• Technical Committee: ISO/IEC JTC 1/SC 25 - Interconnection of information technology equipment
• Drafting Committee: ISO/IEC JTC 1/SC 25 - Interconnection of information technology equipment
• Current Stage: 6060 - International Standard published
• Start Date: 31-Jan-2017
• Due Date: 10-Aug-2016
• Completion Date: 10-Aug-2016

Relations

• Revised: ISO/IEC 14776-232:2001 - Information technology - Small computer system interface (SCSI) - Part 232: Serial Bus Protocol 2 (SBP-2)
• Effective Date: 10-May-2014

Overview

ISO/IEC 14776-323:2017 (SBC-3) - SCSI Block Commands – 3 - defines the model and command set extensions used together with the SCSI Primary Command Set (SPC-4) to support SCSI direct‑access block devices (for example, hard disk drives and block SSDs). The standard specifies behavior, state machines and command interactions that storage devices and hosts must implement to ensure predictable operation, management and interoperability of block storage over SCSI.

Key Topics and Requirements

The standard covers a broad set of technical topics and mandatory behaviors, including:

• Device and command model: definitions for direct‑access block device types, logical and physical block concepts, and command semantics when used with SPC‑4.
• Logical block provisioning: states and management for fully provisioned, thin provisioned and resource‑provisioned logical units (LBP state machine, unmap processing, WRITE SAME interactions).
• Sanitize and initialization: procedures and completion semantics for secure erase and device initialize operations.
• Caching and power loss behavior: read/write caching interactions, command ordering, and effects of power loss on cache contents.
• Error reporting and sense data: structured sense descriptors for block commands, pseudo unrecovered error processing and user data referral descriptors.
• Medium defects and write protection: defect reporting, defect list generation and write protection handling.
• Unmap, de‑duplication and data management: unmap command processing and interactions with provisioning and caches.
• XOR and rebuild support: model for XOR commands used by array subsystems, regenerate/rebuild operations and rebuild‑assist mode.
• State machines and conventions: editorial, numeric and state machine conventions that define transitions and allowable command sequences.

These topics represent behavioral requirements rather than implementation details; implementers must follow the model and command semantics defined when extending SPC‑4.

Applications and Who Uses It

ISO/IEC 14776-323:2017 is essential for:

• Storage device manufacturers (HDD/SSD firmware teams) implementing SCSI block command behavior.
• Storage array and SAN/NAS vendors that rely on consistent unmap, provisioning and XOR/rebuild semantics.
• Operating system and driver developers implementing host-side SCSI command logic and error handling.
• Test labs and QA teams validating interoperability with SPC‑4 and SCSI block command behavior.
• Standards and compliance engineers ensuring products meet SCSI protocol expectations.

Practical benefits include improved interoperability, reliable thin provisioning and unmap behavior, robust error reporting, secure sanitize operations, and standardized support for array rebuild and parity operations.

Related Standards

• SCSI Primary Command Set (SPC‑4) – base standard that SBC‑3 extends.
• Other parts of the ISO/IEC 14776 SCSI family - consult SPC‑4 and relevant SBC parts for full protocol context.

Keywords: ISO/IEC 14776-323:2017, SBC-3, SCSI Block Commands, SCSI direct-access block devices, SPC-4, logical block provisioning, unmap, sanitize operations, caching, error reporting, XOR commands, rebuild assist.

Standards Content (Sample)

ISO/IEC 14776-323
Edition 1.0 2017-01
INTERNATIONAL
STANDARD
colour
inside
Information technology – Small computer system interface (SCSI) –
Part 323: SCSI Block Commands – 3 (SBC-3)

All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form
or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from
either IEC or IEC's member National Committee in the country of the requester. If you have any questions about
ISO/IEC copyright or have an enquiry about obtaining additional rights to this publication, please contact the address
below or your local IEC member National Committee for further information.

IEC Central Office Tel.: [phone]
3, rue de Varembé Fax: [phone]
CH-1211 Geneva 20 [e-mail]
Switzerland www.iec.ch
About the IEC
The International Electrotechnical Commission (IEC) is the leading global organization that prepares and publishes
International Standards for all electrical, electronic and related technologies.

About IEC publications
The technical content of IEC publications is kept under constant review by the IEC. Please make sure that you have the

latest edition, a corrigenda or an amendment might have been published.

IEC Catalogue - webstore.iec.ch/catalogue Electropedia - www.electropedia.org
The stand-alone application for consulting the entire The world's leading online dictionary of electronic and
bibliographical information on IEC International Standards, electrical terms containing 20 000 terms and definitions in
Technical Specifications, Technical Reports and other English and French, with equivalent terms in 15 additional
documents. Available for PC, Mac OS, Android Tablets and languages. Also known as the International Electrotechnical
iPad. Vocabulary (IEV) online.

IEC publications search - www.iec.ch/searchpub IEC Glossary - std.iec.ch/glossary
The advanced search enables to find IEC publications by a 65 000 electrotechnical terminology entries in English and
variety of criteria (reference number, text, technical French extracted from the Terms and Definitions clause of
committee,…). It also gives information on projects, replaced IEC publications issued since 2002. Some entries have been
and withdrawn publications. collected from earlier publications of IEC TC 37, 77, 86 and

CISPR.
IEC Just Published - webstore.iec.ch/justpublished

Stay up to date on all new IEC publications. Just Published IEC Customer Service Centre - webstore.iec.ch/csc
details all new publications released. Available online and If you wish to give us your feedback on this publication or
also once a month by email. need further assistance, please contact the Customer Service
Centre: [e-mail].
ISO/IEC 14776-323
Edition 1.0 2017-01
INTERNATIONAL
STANDARD
colour
inside
Information technology – Small computer system interface (SCSI) –

Part 323: SCSI Block Commands – 3 (SBC-3)

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 35.200 ISBN 978-2-8322-3721-2

– 2 – ISO/IEC 14776-323:2017 © ISO/IEC 2017
– 2 – ISO/IEC 14776-323:2016 © ISO/IEC 2016
FOREWORD . 5
INTRODUCTION . 7
General . 7
SCSI standards family . 7
1 Scope. 8
2 Normative references. 8
3 Terms, definitions, symbols, abbreviations, keywords, and conventions. 9
3.1 Terms and definitions . 9
3.2 Symbols. 19
3.3 Abbreviations. 19
3.4 Keywords. 20
3.5 Editorial conventions . 21
3.6 Numeric and character conventions. 22
3.6.1 Numeric conventions . 22
3.6.2 Units of measure. 22
3.7 State machine conventions . 24
4 Direct access block device type model . 25
4.1 Direct access block device type model introduction. 25
4.2 Direct access block device type model. 26
4.2.1 Direct access block device type model overview. 26
4.2.2 Logical block access command types. 26
4.2.3 Logical block access operation types . 26
4.3 Media examples . 26
4.3.1 Media examples overview. 26
4.3.2 Rotating media. 27
4.3.3 Memory media . 27
4.4 Removable media. 27
4.5 Logical Blocks. 28
4.6 Physical blocks. 29
4.7 Logical block provisioning. 33
4.7.1 Logical block provisioning overview. 33
4.7.2 Fully provisioned logical unit. 34
4.7.3 Logical block provisioning management. 34
4.7.3.1 Logical block provisioning management overview . 34
4.7.3.2 Resource provisioned logical unit. 34
4.7.3.3 Thin provisioned logical unit. 35
4.7.3.4 Unmapping LBAs . 35
4.7.3.4.1 Processing unmap requests . 35
4.7.3.4.2 Unmap operations . 35
4.7.3.4.3 WRITE SAME command and unmap operations . 36
4.7.3.5 Autonomous LBA transitions. 37
4.7.3.6 Thin provisioned logical unit resource exhaustion considerations . 37
4.7.3.7 Logical block provisioning thresholds. 37
4.7.3.7.1 Logical block provisioning thresholds overview. 37
4.7.3.7.2 Logical block provisioning armed decreasing thresholds . 38
4.7.3.7.3 Logical block provisioning armed increasing thresholds. 39
4.7.3.7.4 Logical block provisioning threshold notification.40
4.7.4 LBP (logical block provisioning) state machine. 40
4.7.4.1 LBP state machine overview. 40
4.7.4.2 LBP state machine for thin provisioned logical units supporting anchored LBAs. 41
4.7.4.3 LBP state machine for thin provisioned logical units not supporting anchored LBAs. 41
4.7.4.4 LBP state machine for resource provisioned logical units. 42
4.7.4.5 Performing read operations with respect to logical block provisioning. 42
4.7.4.6 LBP1:Mapped state. 44

ISO/IEC 14776-323:2016 © ISO/IEC 2016 – 3 –
4.7.4.6.1 LBP1:Mapped state description. 44
4.7.4.6.2 Transition LBP1:Mapped to LBP2:Deallocated . 44
4.7.4.6.3 Transition LBP1:Mapped to LBP3:Anchored. 44
4.7.4.7 LBP2:Deallocated state. 44
4.7.4.7.1 LBP2:Deallocated state description. 44
4.7.4.7.2 Transition LBP2:Deallocated to LBP1:Mapped . 44
4.7.4.7.3 Transition LBP2:Deallocated to LBP3:Anchored. 45
4.7.4.8 LBP3:Anchored state . 45
4.7.4.8.1 LBP3:Anchored state description . 45
4.7.4.8.2 Transition LBP3:Anchored to LBP1:Mapped. 45
4.7.4.8.3 Transition LBP3:Anchored to LBP2:Deallocated. 45
4.8 Data de-duplication. 45
4.9 Ready state . 45
4.10 Initialization. 46
4.11 Sanitize operations. 46
4.11.1 Sanitize operations overview . 46
4.11.2 Performing a sanitize operation . 47
4.11.3 Completing a sanitize operation. 48
4.12 Write protection . 49
4.13 Medium defects . 49
4.13.1 Medium defects overview . 49
4.13.2 Generation of defect lists . 52
4.14 Write and unmap failures. 53
4.15 Caches . 53
4.15.1 Caches overview. 53
4.15.2 Read caching. 53
4.15.3 Write caching . 53
4.15.4 Command interactions with caches . 54
4.15.5 Write operation and write medium operation interactions with caches. 54
4.15.6 Read operation and read medium operation interactions with caches . 54
4.15.7 Verify medium operation interactions with caches. 55
4.15.8 Unmap operation interactions with caches . 55
4.15.9 Power loss effects on caches . 55
4.16 Implicit head of queue command processing . 56
4.17 Reservations. 56
4.18 Error reporting . 58
4.18.1 Error reporting overview. 58
4.18.2 Processing pseudo unrecovered errors. 60
4.18.3 Block commands sense data descriptor . 61
4.18.4 User data segment referral sense data descriptor. 62
4.18.5 Direct-access block device sense data descriptor. 64
4.19 Model for XOR commands . 65
4.19.1 Model for XOR commands overview . 65
4.19.2 SCSI storage array device supervised XOR operations. 66
4.19.2.1 SCSI storage array device supervised XOR operations overview . 66
4.19.2.2 Update write operation . 66
4.19.2.3 Regenerate operation. 66
4.19.2.4 Rebuild operation . 67
4.19.3 Array subsystem considerations. 67
4.19.3.1 Array subsystem considerations overview . 67
4.19.3.2 Access to an inconsistent stripe. 67
4.20 Rebuild assist mode . 67
4.20.1 Rebuild assist mode overview . 67
4.20.2 Enabling rebuild assist mode. 68
4.20.3 Using the rebuild assist mode. 68
4.20.3.1 Using rebuild assist mode overview. 68
4.20.3.2 Unpredicted unrecovered read error . 68
4.20.3.3 Predicted unrecovered read error . 69

– 4 – ISO/IEC 14776-323:2017 © ISO/IEC 2017
– 4 – ISO/IEC 14776-323:2016 © ISO/IEC 2016
4.20.3.4 Unpredicted unrecovered write error. 69
4.20.3.5 Predicted unrecovered write error. 69
4.20.4 Disabling the rebuild assist mode . 70
4.20.5 Testing rebuild assist mode . 70
4.21 START STOP UNIT and power conditions. 70
4.21.1 START STOP UNIT and power conditions overview. 70
4.21.2 Processing of concurrent START STOP UNIT commands. 70
4.21.3 Managing logical block access commands during a change to the active power condition . 71
4.21.4 Stopped power condition . 71
4.21.5 START STOP UNIT and power condition state machine . 71
4.21.5.1 START STOP UNIT and power condition state machine overview. 71
4.21.5.2 SSU_PC0:Powered_On state . 73
4.21.5.2.1 SSU_PC0:Powered_On state description . 73
4.21.5.2.2 Transition SSU_PC0:Powered_On to SSU_PC4:Active_Wait . 74
4.21.5.2.3 Transition SSU_PC0:Powered_On to SSU_PC8:Stopped. 74
4.21.5.3 SSU_PC1:Active state . 74
4.21.5.3.1 SSU_PC1:Active state description . 74
4.21.5.3.2 Transition SSU_PC1:Active to SSU_PC5:Wait_Idle . 74
4.21.5.3.3 Transition SSU_PC1:Active to SSU_PC6:Wait_Standby. 74
4.21.5.3.4 Transition SSU_PC1:Active to SSU_PC10:Wait_Stopped. 75
4.21.5.4 SSU_PC2:Idle state . 75
4.21.5.4.1 SSU_PC2:Idle state description . 75
4.21.5.4.2 Transition SSU_PC2:Idle to SSU_PC4:Active_Wait . 75
4.21.5.4.3 Transition SSU_PC2:Idle to SSU_PC5:Wait_Idle . 75
4.21.5.4.4 Transition SSU_PC2:Idle to SSU_PC6:Wait_Standby. 76
4.21.5.4.5 Transition SSU_PC2:Idle to SSU_PC7:Idle_Wait . 76
4.21.5.4.6 Transition SSU_PC2:Idle to SSU_PC10:Wait_Stopped. 76
4.21.5.5 SSU_PC3:Standby state. 76
4.21.5.5.1 SSU_PC3:Standby state description.76
4.21.5.5.2 Transition SSU_PC3:Standby to SSU_PC4:Active_Wait. 76
4.21.5.5.3 Transition SSU_PC3:Standby to SSU_PC6:Wait_Standby. 77
4.21.5.5.4 Transition SSU_PC3:Standby to SSU_PC7:Idle_Wait. 77
4.21.5.5.5 Transition SSU_PC3:Standby to SSU_PC9:Standby_Wait. 77
4.21.5.5.6 Transition SSU_PC3:Standby to SSU_PC10:Wait_Stopped . 78
4.21.5.6 SSU_PC4:Active_Wait state . 78
4.21.5.6.1 SSU_PC4:Active_Wait state description . 78
4.21.5.6.2 Transition SSU_PC4:Active_Wait to SSU_PC1:Active . 79
4.21.5.7 SSU_PC5:Wait_Idle state . 79
4.21.5.7.1 SSU_PC5:Wait_Idle state description .79
4.21.5.7.2 Transition SSU_PC5:Wait_Idle to SSU_PC2:Idle . 79
4.21.5.8 SSU_PC6:Wait_Standby state. 79
4.21.5.8.1 SSU_PC6:Wait_Standby state description. 79
4.21.5.8.2 Transition SSU_PC6:Wait_Standby to SSU_PC3:Standby. 79
4.21.5.9 SSU_PC7:Idle_Wait state . 79
4.21.5.9.1 SSU_PC7:Idle_Wait state description .79
4.21.5.9.2 Transition SSU_PC7:Idle_Wait to SSU_PC2:Idle . 80
4.21.5.10 SSU_PC8:Stopped state. 80
4.21.5.10.1 SSU_PC8:Stopped state description. 80
4.21.5.10.2 Transition SSU_PC8:Stopped to SSU_PC4:Active_Wait. 80
4.21.5.10.3 Transition SSU_PC8:Stopped to SSU_PC7:Idle_Wait. 81
4.21.5.10.4 Transition SSU_PC8:Stopped to SSU_PC9:Standby_Wait . 81
4.21.5.11 SSU_PC9:Standby_Wait state. 81
4.21.5.11.1 SSU_PC9:Standby_Wait state description. 81
4.21.5.11.2 Transition SSU_PC9:Standby_Wait to SSU_PC3:Standby. 81
4.21.5.12 SSU_PC10:Wait_Stopped state. 82
4.21.5.12.1 SSU_PC10:Wait_Stopped state description. 82
4.21.5.12.2 Transition SSU_PC10:Wait_Stopped to SSU_PC8:Stopped . 82
4.22 Protection information model. 82

ISO/IEC 14776-323:2016 © ISO/IEC 2016 – 5 –
4.22.1 Protection information overview. 82
4.22.2 Protection types . 82
4.22.2.1 Protection types overview . 82
4.22.2.2 Type 0 protection. 83
4.22.2.3 Type 1 protection. 84
4.22.2.4 Type 2 protection. 84
4.22.2.5 Type 3 protection. 85
4.22.3 Protection information format. 85
4.22.4 Logical block guard. 89
4.22.4.1 Logical block guard overview . 89
4.22.4.2 CRC generation. 89
4.22.4.3 CRC checking . 90
4.22.4.4 CRC test cases . 90
4.22.5 Application of protection information. 90
4.22.6 Protection information and commands . 91
4.23 Grouping function . 91
4.24 Background scan operations. 91
4.24.1 Background scan overview. 91
4.24.2 Background pre-scan operations. 92
4.24.2.1 Enabling background pre-scan operations. 92
4.24.2.2 Suspending and resuming background pre-scan operations. 92
4.24.2.3 Halting background pre-scan operations. 93
4.24.3 Background medium scan . 93
4.24.3.1 Enabling background medium scan operations . 93
4.24.3.2 Suspending and resuming background medium scan operations. 94
4.24.3.3 Halting background medium scan operations . 94
4.24.4 Interpreting the logged background scan results. 95
4.25 Association between commands and CbCS permission bits . 95
4.26 Deferred microcode activation. 97
4.27 Model for uninterrupted sequences on LBA ranges . 97
4.28 Referrals. 97
4.28.1 Referrals overview . 97
4.28.2 Discovering referrals. 98
4.28.3 Referrals in sense data. 99
4.29 ORWRITE commands. 100
4.29.1 ORWRITE commands overview . 100
4.29.2 ORWgeneration code . 100
4.29.2.1 ORWgeneration code overview. 100
4.29.2.2 ORWgeneration code processing . 101
4.29.3 Change generation and clear operation. 101
4.29.4 Set operation. 103
4.30 Block device ROD token operations. 104
4.30.1 Block device ROD token operations overview.104
4.30.2 POPULATE TOKEN command and WRITE USING TOKEN command completion. 105
4.30.3 Block device specific ROD tokens . 105
4.30.4 Block device zero ROD token. 106
4.30.5 ROD token device type specific data. 106
5 Commands for direct access block devices. 108
5.1 Commands for direct access block devices overview .108
5.2 COMPARE AND WRITE command . 111
5.3 FORMAT UNIT command . 113
5.3.1 FORMAT UNIT command overview . 113
5.3.2 FORMAT UNIT parameter list. 117
5.3.2.1 FORMAT UNIT parameter list overview.117
5.3.2.2 Parameter list header. 117
5.3.2.3 Initialization pattern descriptor. 122
5.4 GET LBA STATUS command . 123

– 6 – ISO/IEC 14776-323:2017 © ISO/IEC 2017
– 6 – ISO/IEC 14776-323:2016 © ISO/IEC 2016
5.4.1 GET LBA STATUS command overview.123
5.4.2 GET LBA STATUS parameter data . 125
5.4.2.1 GET LBA STATUS parameter data overview . 125
5.4.2.2 LBA status descriptor . 126
5.4.2.3 LBA status descriptor relationships. 126
5.5 ORWRITE (16) command . 127
5.6 ORWRITE (32) command . 133
5.7 POPULATE TOKEN command . 135
5.7.1 POPULATE TOKEN command overview . 135
5.7.2 POPULATE TOKEN parameter list. 136
5.7.3 Block device range descriptor. 138
5.8 PRE-FETCH (10) command. 139
5.9 PRE-FETCH (16) command. 140
5.10 PREVENT ALLOW MEDIUM REMOVAL command. 141
5.11 READ (10) command . 142
5.12 READ (12) command . 146
5.13 READ (16) command . 148
5.14 READ (32) command . 149
5.15 READ CAPACITY (10) command . 150
5.15.1 READ CAPACITY (10) overview . 150
5.15.2 READ CAPACITY (10) parameter data . 151
5.16 READ CAPACITY (16) command . 151
5.16.1 READ CAPACITY (16) command overview. 151
5.16.2 READ CAPACITY (16) parameter data . 152
5.17 READ DEFECT DATA (10) command . 154
5.17.1 READ DEFECT DATA (10) command overview. 154
5.17.2 READ DEFECT DATA (10) parameter data . 156
5.18 READ DEFECT DATA (12) command . 156
5.18.1 READ DEFECT DATA (12) command overview. 156
5.18.2 READ DEFECT DATA (12) parameter data . 158
5.19 READ LONG (10) command . 159
5.20 READ LONG (16) command . 161
5.21 REASSIGN BLOCKS command. 161
5.21.1 REASSIGN BLOCKS command overview. 161
5.21.2 REASSIGN BLOCKS parameter list. 163
5.22 RECEIVE ROD TOKEN INFORMATION . 165
5.22.1 RECEIVE ROD TOKEN INFORMATION overview . 165
5.22.2 RECEIVE ROD TOKEN INFORMATION parameter data for POPULATE TOKEN command. 165
5.22.3 The RECEIVE ROD TOKEN INFORMATION parameter data for the WRITE USING
TOKEN command. 168
5.23 REPORT REFERRALS command . 169
5.23.1 REPORT REFERRALS command overview . 169
5.23.2 REPORT REFERRALS parameter data. 170
5.24 SANITIZE command. 171
5.24.1 SANITIZE command overview. 171
5.24.2 SANITIZE command service actions . 172
5.24.2.1 SANITIZE command service actions overview . 172
5.24.2.2 OVERWRITE service action. 172
5.24.2.3 BLOCK ERASE service action. 173
5.24.2.4 CRYPTOGRAPHIC ERASE service action. 174
5.24.2.5 EXIT FAILURE MODE service action . 174
5.25 START STOP UNIT command. 174
5.26 SYNCHRONIZE CACHE (10) command.178
5.27 SYNCHRONIZE CACHE (16) command.179
5.28 UNMAP command. 180
5.28.1 UNMAP command overview. 180
5.28.2 UNMAP parameter list . 181
5.29 VERIFY (10) command . 182

ISO/IEC 14776-323:2016 © ISO/IEC 2016 – 7 –
5.30 VERIFY (12) command . 195
5.31 VERIFY (16) command . 196
5.32 VERIFY (32) command . 197
5.33 WRITE (10) command. 198
5.34 WRITE (12) command. 201
5.35 WRITE (16) command. 202
5.36 WRITE (32) command. 203
5.37 WRITE AND VERIFY (10) command . 204
5.38 WRITE AND VERIFY (12) command . 205
5.39 WRITE AND VERIFY (16) co
...