Write buffer (3bh), What the library does with this command, Command usage – Dell PowerVault ML6000 User Manual
Page 89: Write buffer cdb format
PowerVault ML6000 SCSI Reference Guide
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Write Buffer (3Bh)
What the Library Does With This Command
The library will receive a requested buffer of data and write it to the appropriate internal storage. The
Controller logical unit is the primary device to use with this command, since the Media Changer logical units
only support the echo buffer mode.
Command Usage
This command can be used primarily to download new firmware to the library, as well as to perform
enhanced domain validation (using the echo buffer mode). The initiator can either transfer the data with a
single WRITE BUFFER command, or it can also transfer it in blocks utilizing offsets into the buffer.
Write Buffer CDB Format
The WRITE BUFFER CDB format is shown in the following table.
Mode – The supported modes are:
•
2h – Data
•
Ah – Echo Buffer
In Data Mode, an amount of data specified by the Parameter List Length is targeted for the buffer defined
by the Buffer ID field, starting at the specified Buffer Offset. Buffer IDs are assigned beginning with zero,
and are assigned contiguously. Buffer ID code assignments for the WRITE BUFFER command are the
same as for the READ BUFFER command.
In Echo Buffer Mode, the amount of data specified by the Parameter List Length is transferred from the
initiator to the echo buffer. The Buffer ID and Buffer Offset fields are ignored in this mode.
Buffer ID – This field specifies which buffer the request is for. The IDs are the same for both the READ
BUFFER and WRITE BUFFER commands. The IDs supported by the library, along with their primary use,
are listed in
Table 76
WRITE BUFFER CDB format
Bit
Byte
7
6
5
4
3
2
1
0
0
Op Code (3Bh)
1
Logical Unit Number
Rsvd
Mode
2
Buffer ID
3
Buffer Offset
5
6
Parameter List Length
8
9
Control