CDB Structure Explained

Overview

This topic describes the SCSI Command Descriptor Block (CDB) Link will open in new window. structure that displays in the messages file.  This will focus on the first parameter which is the operation code. 
 

CDB Example

Below is an example of a CDB from a messages file on a DXi system with 1.4.0.3 software. This information may display differently in other DXi software versions. 
 
Oct 20 16:54:29 DA1QUDXI101 kernel: EQTMP Ser:VL01CXi CmdPtr:ffff81054d0082f8 IOSer:152128120 CMD:0x12 On aborting active cmd 1097 st 2 fl 0, ffff81054d0082f8 LUN: 0 tag:9114A78 llt: 4 CDB: 0x12 0 0 0 24 0 0 0 0 0 0 0 state: 0x1 [0:0:0:0:0] [0:0:0:0:3] flags: 1 t: 8053ms[S/0/115][S/115/116][S/116/0][S/0/1][P/0/1][P/1/2]
 
The CDB example above points to an INQUIRY since the Operation Code, the first parameter in the CDB, is 0x12. CDB structure and a list of the Operation Codes are listed below in the SCSI Command Operation Codes section. The entire CDB structure itself depends on the Operation Code and will not be covered here. 

 


SCSI Command Operation Codes

List of SCSI command Operation Codes.
Code↓ Command↓
00         TEST UNIT READY (mandatory)
01         RECALIBRATE or REWIND
03         REQUEST SENSE (mandatory except RBC)
04         FORMAT UNIT
05         READ BLOCK LIMITS
07         REASSIGN BLOCKS
07         INITIALIZE ELEMENT STATUS
08         READ (6)
0A        WRITE (6)
0B        SEEK (6)
0F        READ REVERSE (6)
10         WRITE FILEMARKS (6)
11         SPACE (6)
12         INQUIRY (mandatory)
13         VERIFY(6)
14         RECOVER BUFFERED DATA
15         MODE SELECT (6)
16         RESERVE (6)
17         RELEASE (6)
18         COPY
19         ERASE (6)
1A        MODE SENSE (6)
1B        START/STOP UNIT
1B        LOAD UNLOAD
1C        RECEIVE DIAGNOSTIC RESULTS
1D        SEND DIAGNOSTIC
1E        PREVENT/ALLOW MEDIUM REMOVAL
23         READ FORMAT CAPACITIES (MMC)
24         SET WINDOW
25         READ CAPACITY (10)
28         READ (10)
29         READ GENERATION
2A        WRITE (10)
2B        SEEK (10)
2C        ERASE (10)
2D        READ UPDATED BLOCK
2E        WRITE AND VERIFY (10)
2F        VERIFY (10)
30         SEARCH DATA HIGH (10)
31         SEARCH DATA EQUAL (10)
32         SEARCH DATA LOW (10)
33         SET LIMITS (10)
34         PRE-FETCH (10)
35         SYNCHRONIZE CACHE (10)
36         LOCK/UNLOCK CACHE (10)
37         READ DEFECT DATA (10)
37         INITIALIZE ELEMENT STATUS WITH RANGE
38         MEDIUM SCAN
39         COMPARE
3A        COPY AND VERIFY
3B        WRITE BUFFER
3C        READ BUFFER
3D        UPDATE BLOCK
3E        READ LONG
3F        WRITE LONG
40         CHANGE DEFINITION
41         WRITE SAME (10)
44         REPORT DENSITY SUPPORT
45         PLAY AUDIO (10)
46         GET CONFIGURATION
47         PLAY AUDIO MSF
4A        GET EVENT STATUS NOTIFICATION
4B        PAUSE / RESUME
4C        LOG SELECT
4D        LOG SENSE
50         XDWRITE (10)
51         XPWRITE (10)
52         XDREAD (10)
53         XDWRITEREAD (10)
54         SEND OPC INFORMATION
55         MODE SELECT (10)
56         RESERVE (10)
57         RELEASE (10)
58         REPAIR TRACK
5A        MODE SENSE (10)
5B        CLOSE TRACK / SESSION
5C        READ BUFFER CAPACITY
5D        SEND CUE SHEET
5E        PERSISTENT RESERVE IN
5F        PERSISTENT RESERVE OUT
7E        EXTENDED CDB
7F        VARIABLE LENGTH CDB
80         XDWRITE EXTENDED (16)
80         WRITE FILEMARKS (16)
81         REBUILD (16)
81         READ REVERSE (16)
82         REGENERATE (16)
83         EXTENDED COPY
84         RECEIVE COPY RESULTS
85         ATA COMMAND PASS THROUGH (16)
86         ACCESS CONTROL IN
87         ACCESS CONTROL OUT
88         READ (16)
89         COMPARE AND WRITE
8A        WRITE (16)
8B        ORWRITE
8C        READ ATTRIBUTE
8D        WRITE ATTRIBUTE
8E        WRITE AND VERIFY (16)
8F        VERIFY (16)
90         PRE-FETCH (16)
91         SYNCHRONIZE CACHE (16)
92         SPACE (16)
92         LOCK UNLOCK CACHE (16)
93         WRITE SAME (16)
9E        SERVICE ACTION IN (16)
9F        SERVICE ACTION OUT (16)
A0        REPORT LUNS
A1        ATA COMMAND PASS THROUGH (12)
A2        SECURITY PROTOCOL IN
A3        REPORT SUPPORTED OPCODES
A4        MAINTENANCE (OUT) (REPORT_KEY)
A5        MOVE MEDIUM
A6        EXCHANGE MEDIUM
A7        MOVE MEDIUM ATTACHED
A8        READ (12)
A9        SERVICE ACTION OUT (12)
AA        WRITE (12)
AB        SERVICE ACTION IN (12)
AC        ERASE (12)
AD       READ DVD STRUCTURE
AE        WRITE AND VERIFY (12)
AF        VERIFY (12)
B0        SEARCH DATA HIGH (12)
B1        SEARCH DATA EQUAL (12)
B2        SEARCH DATA LOW (12)
B3        SET LIMITS (12)
B4        READ ELEMENT STATUS ATTACHED
B5        SECURITY PROTOCOL OUT
B6        SEND VOLUME TAG
B7        READ DEFECT DATA (12)
B8        READ ELEMENT STATUS
B9        READ CD MSF
BA        REDUNDANCY GROUP (IN)
BB        REDUNDANCY GROUP (OUT)
BC        SPARE (IN)
BD       SPARE (OUT)
BE        VOLUME SET (IN)
BF        VOLUME SET (OUT)

 


Additional Information

 

 



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