SCSI command

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In SCSI computer storage, a command is the basic unit of communication. The SCSI command architecture was originally defined for parallel SCSI buses but has been carried forward with minimal change for use with Fibre Channel, iSCSI and Serial Attached SCSI.

In SCSI protocol, the initiator sends a SCSI command to the target which then responds. SCSI commands are sent in a Command Descriptor Block (CDB). The CDB consists of a one byte operation code followed by five or more bytes containing command-specific parameters. At the end of the command the target returns a Status Code byte.

The rest of this article contains a list of SCSI commands, firstly in operation code order and secondly in alphabetical order. There are links to detailed descriptions for the more common SCSI commands:

[edit] List of SCSI commands by operation code

Code Command
00 TEST UNIT READY
01 REZERO UNIT
03 REQUEST SENSE
04 FORMAT UNIT
07 REASSIGN BLOCKS
08 READ (6)
0A WRITE (6)
0B SEEK (6)
11 SPACE (6)
12 INQUIRY
15 MODE SELECT (6)
16 RESERVE (6)
17 RELEASE (6)
18 COPY
1A MODE SENSE (6)
1B START/STOP UNIT
1C RECEIVE DIAGNOSTIC RESULTS
1D SEND DIAGNOSTIC
1E PREVENT/ALLOW MEDIUM REMOVAL
23 READ FORMAT CAPACITIES (MMC)
25 READ CAPACITY
28 READ (10)
2A WRITE (10)
2B SEEK (10)
2E WRITE AND VERIFY
2F VERIFY
30 SEARCH DATA HIGH
31 SEARCH DATA EQUAL
32 SEARCH DATA LOW
33 SET LIMITS (10)
34 PRE-FETCH
35 SYNCHRONIZE CACHE
36 LOCK/UNLOCK CACHE
37 READ DEFECT DATA
39 COMPARE
3A COPY AND VERIFY
3B WRITE BUFFER
3C READ BUFFER
3E READ LONG
3F WRITE LONG
40 CHANGE DEFINITION
41 WRITE SAME
4C LOG SELECT
4D LOG SENSE
50 XDWRITE
51 XPWRITE
52 XDREAD
55 MODE SELECT (10)
56 RESERVE (10)
57 RELEASE (10)
5A MODE SENSE (10)
5E PERSISTENT RESERVE IN
5F PERSISTENT RESERVE OUT
80 XDWRITE EXTENDED
82 REGENERATE
A0 REPORT LUNS
A5 MOVE MEDIUM
A8 READ (12)
AA WRITE (12)
B3 SET LIMITS (12)
B4 READ ELEMENT STATUS
B7 READ DEFECT DATA (12)

[edit] List of SCSI commands, alphabetical

Code Command
40 CHANGE DEFINITION
39 COMPARE
18 COPY
3A COPY AND VERIFY
04 FORMAT UNIT
12 INQUIRY {Mandatory}
36 LOCK/UNLOCK CACHE
4C LOG SELECT
4D LOG SENSE
15 MODE SELECT (6)
55 MODE SELECT (10)
1A MODE SENSE (6)
5A MODE SENSE (10)
A5 MOVE MEDIUM
5E PERSISTENT RESERVE IN
5F PERSISTENT RESERVE OUT
34 PRE-FETCH
1E PREVENT/ALLOW MEDIUM REMOVAL
08 READ (6)
28 READ (10)
A8 READ (12)
3C READ BUFFER
25 READ CAPACITY
37 READ DEFECT DATA (10)
B7 READ DEFECT DATA (12)
B4 READ ELEMENT STATUS
23 READ FORMAT CAPACITIES (MMC)
3E READ LONG
07 REASSIGN BLOCKS
1C RECEIVE DIAGNOSTIC RESULTS
82 REGENERATE
17 RELEASE (6)
57 RELEASE (10)
A0 REPORT LUNS
03 REQUEST SENSE {Mandatory}
16 RESERVE (6)
56 RESERVE (10)
01 REZERO UNIT
31 SEARCH DATA EQUAL
30 SEARCH DATA HIGH
32 SEARCH DATA LOW
0B SEEK (6)
2B SEEK (10)
1D SEND DIAGNOSTIC {Mandatory}
33 SET LIMITS (10)
B3 SET LIMITS (12)
11 SPACE (6)
1B START/STOP UNIT
35 SYNCHRONIZE CACHE
00 TEST UNIT READY {Mandatory}
2F VERIFY
0A WRITE (6)
2A WRITE (10)
AA WRITE (12)
2E WRITE AND VERIFY
3B WRITE BUFFER
3F WRITE LONG
41 WRITE SAME
52 XDREAD
50 XDWRITE
80 XDWRITE EXTENDED
51 XPWRITE

[edit] External links