SCSI CDB
From Wikipedia, the free encyclopedia
In SCSI computer storage, commands are sent in a Command Descriptor Block (CDB).
Each CDB can be a total of 6, 10, 12, or 16 bytes, but later versions of the SCSI standard also allow for variable-length CDBs. The CDB consists of a one byte operation code followed by some command-specific parameters.
A typical CDB structure is:
bit→ ↓byte |
7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 |
---|---|---|---|---|---|---|---|---|
0 | Operation code = 03h | |||||||
1 | LUN | Reserved | ||||||
2 | Reserved | |||||||
3 | Reserved | |||||||
4 | Allocation length | |||||||
5 | Control |