HGST Ultrastar 7K4000 (SAS) Hard Disk Drive Specification
265
18.60 WRITE BUFFER (3B)
Table 223: WRITE BUFFER (3B)
The WRITE BUFFER command is used in conjunction with the READ BUFFER command as a diagnostic function for test-
ing the memory of the drive and the SCSI bus integrity. This command does not alter the medium of the drive. Additional
modes are provided for downloading microcode and saving microcode.
This command will cause the entire cache to be emptied.
The function of this command and the meaning of fields within the command descriptor block depend on the contents of the
mode field.
MODE Description
00000 Write combined header and data
00010 Data
00100 Download Microcode
00101 Download Microcode and Save - single binary file
00111 Download Microcode and Save - multiple binary files
01010 Write Data to Echo Buffer
01110 Download microcode with offsets, save, and defer activate
01111 Activate deferred microcode
11010 Enable expander Communications Protocol
All Others Not Supported
If any values other than shown above are specified, Check Condition status is returned with a sense key of Illegal Request and
additional sense code of Invalid Field in CDB.
18.60.1 Combined Header And Data (Mode 00000b)
In this mode, the data to be transferred is preceded by a four-byte header.
Buffer ID must be zero. If another value is specified, no download function is performed and the command is terminated with
Check Condition status. And the drive shall set the sense key to Illegal Request and additional sense code to Illegal Field in
CDB.
Buffer Offset must be zero. If another value is specified, no download function is performed and the command is terminated
with Check Condition status. And the drive shall set the sense key to Illegal Request and additional sense code to Illegal Field
Byte
Bit
76543210
0 Command Code = 3Bh
1 Reserved = 0 Mode
2 Buffer ID
3-5 Buffer Offset
6-8 Parameter List Length
9 VU = 0 Reserved = 0 FLAG LINK
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