Skip to content

SCSI_COMMANDS.md

Latest commit

 

History

History
197 lines (151 loc) · 8.5 KB

SCSI_COMMANDS.md

File metadata and controls

197 lines (151 loc) · 8.5 KB

SCSI Commands Support

This document lists all SCSI commands supported by gotgt iSCSI target implementation.

Overview

gotgt implements SCSI Primary Commands (SPC-3/4) and SCSI Block Commands (SBC-2/3) to provide a complete iSCSI target solution for block storage devices.

Supported SCSI Commands

SPC Commands (Primary Commands)

Opcode Command Name Description Status
0x00 TEST UNIT READY Check if device is ready ✅ Supported
0x03 REQUEST SENSE Request sense data ✅ Supported
0x12 INQUIRY Get device information ✅ Supported
0x1A MODE SENSE (6) Get device parameters ✅ Supported
0x5A MODE SENSE (10) Get device parameters ✅ Supported
0x15 MODE SELECT (6) Set device parameters ✅ Supported
0x55 MODE SELECT (10) Set device parameters ✅ Supported
0x1B START STOP UNIT Control device power state ✅ Supported
0x1E PREVENT ALLOW MEDIUM REMOVAL Control media removal ✅ Supported
0xA0 REPORT LUNS Report LUN inventory ✅ Supported
0x1D SEND DIAGNOSTIC Run diagnostics ✅ Supported
0x5E PERSISTENT RESERVE IN Read reservation info ✅ Supported
0x5F PERSISTENT RESERVE OUT Modify reservations ✅ Supported
0xA3 MAINTENANCE IN Maintenance commands ✅ Supported (Report Supported Operation Codes)

SBC Commands (Block Commands)

Opcode Command Name Description Status
0x08 READ (6) Read data (21-bit LBA) ✅ Supported
0x28 READ (10) Read data (32-bit LBA) ✅ Supported
0xA8 READ (12) Read data (32-bit LBA) ✅ Supported
0x88 READ (16) Read data (64-bit LBA) ✅ Supported
0x0A WRITE (6) Write data (21-bit LBA) ✅ Supported
0x2A WRITE (10) Write data (32-bit LBA) ✅ Supported
0xAA WRITE (12) Write data (32-bit LBA) ✅ Supported
0x8A WRITE (16) Write data (64-bit LBA) ✅ Supported
0x2E WRITE AND VERIFY (10) Write and verify ✅ Supported
0xAE WRITE AND VERIFY (12) Write and verify ✅ Supported
0x8E WRITE AND VERIFY (16) Write and verify ✅ Supported
0x41 WRITE SAME (10) Write same pattern ✅ Supported
0x93 WRITE SAME (16) Write same pattern ✅ Supported
0x8B ORWRITE (16) OR write operation ✅ Supported
0x89 COMPARE AND WRITE Atomic compare and write ✅ Supported
0x25 READ CAPACITY (10) Get device capacity ✅ Supported
0x9E SERVICE ACTION IN (16) Read capacity (16) ✅ Supported
0x2F VERIFY (10) Verify data integrity ✅ Supported
0xAF VERIFY (12) Verify data integrity ✅ Supported
0x8F VERIFY (16) Verify data integrity ✅ Supported
0x34 PRE-FETCH (10) Cache data ✅ Supported
0x90 PRE-FETCH (16) Cache data ✅ Supported
0x35 SYNCHRONIZE CACHE (10) Flush cache ✅ Supported
0x91 SYNCHRONIZE CACHE (16) Flush cache ✅ Supported
0x42 UNMAP Deallocate blocks ✅ Supported
0x04 FORMAT UNIT Format media ✅ Supported
0x16 RESERVE (6) Reserve device ✅ Supported
0x17 RELEASE (6) Release device ✅ Supported

Persistent Reservation Service Actions

PR IN Service Actions

Service Action Name Description Status
0x00 READ KEYS Read reservation keys ✅ Supported
0x01 READ RESERVATION Read current reservation ✅ Supported
0x02 REPORT CAPABILITIES Report PR capabilities ✅ Supported

PR OUT Service Actions

Service Action Name Description Status
0x00 REGISTER Register reservation key ✅ Supported
0x01 RESERVE Reserve device ✅ Supported
0x02 RELEASE Release reservation ✅ Supported
0x03 CLEAR Clear all reservations ✅ Supported
0x04 PREEMPT Preempt reservation ✅ Supported
0x06 REGISTER AND IGNORE EXISTING KEY Register new key ✅ Supported
0x07 REGISTER AND MOVE Register and move ✅ Supported

Supported VPD Pages

The INQUIRY command supports the following Vital Product Data (VPD) pages:

Page Code Name Description Status
0x00 Supported VPD Pages List of supported VPD pages ✅ Supported
0x80 Unit Serial Number Device serial number ✅ Supported
0x83 Device Identification Device identifiers ✅ Supported
0xB0 Block Limits Block device limits ✅ Supported
0xB2 Logical Block Provisioning Thin provisioning info ✅ Supported

Supported Mode Pages

The MODE SENSE command supports the following mode pages:

Page Code Name Description Status
0x02 Disconnect-Reconnect Disconnect/reconnect parameters ✅ Supported
0x08 Caching Cache control parameters ✅ Supported
0x0A Control Control mode parameters ✅ Supported
0x0A/0x01 Control Extension Extended control parameters ✅ Supported
0x1C Informational Exceptions SMART control parameters ✅ Supported

iSCSI Protocol Features

Feature Description Status
Login Authentication CHAP authentication ✅ Supported
Multiple Connections Multiple TCP connections per session ✅ Supported
Header Digest CRC32C header integrity ✅ Supported
Data Digest CRC32C data integrity ✅ Supported
Immediate Data Immediate data delivery ✅ Supported
Unsolicited Data Unsolicited data-out PDUs ✅ Supported
Error Recovery Level Error recovery mechanisms Level 0 Supported

Tested with libiscsi

All commands have been tested with the libiscsi test suite. The following test categories are fully supported:

  • ✅ Inquiry commands (including EVPD handling)
  • ✅ Read operations (6/10/12/16 byte CDBs)
  • ✅ Write operations (6/10/12/16 byte CDBs)
  • ✅ Write and Verify operations
  • ✅ Verify operations
  • ✅ Capacity reporting
  • ✅ Mode Sense/Select operations
  • ✅ Persistent Reservation operations
  • ✅ Unmap/Trim operations
  • ✅ Synchronize Cache operations
  • ✅ iSCSI protocol compliance

Test Results

Total Tests: 38
Passed: 38
Failed: 0
Pass Rate: 100%

Tested with libiscsi test suite covering all major SCSI command categories.

Recent Fixes

Bug Fix: SCSICDBBufXLength Function (2025-03-10)

Fixed incorrect Allocation Length calculation for 6-byte CDB commands:

  1. INQUIRY (0x12) and REQUEST_SENSE (0x03): Use bytes 3-4 for Allocation Length
  2. Other Group 0 commands (READ_6, WRITE_6, etc.): Return ok=false since these commands don't have Allocation Length field in their CDB. This prevents incorrect truncation of sense data buffer.

Bug Fix: CDB Group ID Comparison (2025-03-10)

Fixed incorrect comparison between CDB length constants and group IDs:

  • Original: Used CDB length constants (6, 10, 12, 16) which were incorrect
  • Fixed: Use actual group IDs (0-7) for switch statement

Bug Fix: PERSISTENT_RESERVE_IN/OUT (0x5E/0x5F) (2025-03-10)

Fixed Allocation Length position for these commands:

  • Use bytes 6-7 instead of bytes 7-8
  • Added manual BigEndian conversion for correct byte order

Notes

Block Device Characteristics VPD Page (0xB1)

This VPD page is currently not supported. The INQUIRY command will return a CHECK CONDITION status with ILLEGAL_REQUEST sense key when this page is requested. This is expected behavior and does not affect normal operations.

Persistent Reservations

  • All standard reservation types are supported: Write Exclusive, Exclusive Access, and their variants with registrants only.
  • Reservation scopes: LU (Logical Unit) scope is supported.
  • Persistent reservation operations require proper key registration before use.

Thin Provisioning

  • UNMAP command is fully supported for thin-provisioned LUNs.
  • Logical Block Provisioning VPD page (0xB2) reports thin provisioning capabilities.

Version Information

  • SPC Version: SPC-3 (with some SPC-4 features)
  • SBC Version: SBC-2 (with some SBC-3 features)
  • iSCSI Protocol: RFC 3720 compliant

References