
2-10
SCSI REFERENCE 1014826
CHAPTER 2—OVERVIEW OF THE LIBRARY AS A SCSI DEVICE
2.2.2 SCSI COMMAND FORMAT
The library uses six-, ten-, and twelve-byte commands, whose formats are
described in the SCSI-3 standards (SPC-2, SMC-2, SAM-2). Any command
descriptor block (CDB) fields that are specific to the library for a given
command are described in the command chapter. This section describes the
CDB fields that are common for every command.
Note: Any errors caused by illegal parameters in a CDB or parameter list for a
particular command are listed at the end of the command chapter. Errors
of this type return a sense key of Illegal Request (5h).
The word Reserved or RSVD has one of the following meanings when used
in a SCSI command field definition:
The field is defined as reserved by the ANSI Small Computer System
Interface (SCSI) standard. The library checks these fields for a value of 0.
If zeros are not present, the library returns Check Condition status with
the sense key set to Illegal Request (5h).
REQUEST VOLUME
ELEMENT ADDRESS
(12 bytes)
B5h Returns the element descriptors (including element
address and status flags for each element) created as
a result of the SEND VOLUME TAG command.
Data is returned in element address order.
Chapter 19
RESERVE
(6 bytes or 10 bytes)
16h
56h
Reserves the library for the initiator’s use. Chapter 20
REZERO UNIT
(6 bytes)
01h Implemented to provide software compatibility
when it is required. Because the library does not
need to calibrate its mechanics, it always returns
and immediate Good status in response to this
command.
Chapter 21
SEND DIAGNOSTIC
(6 bytes)
1Dh Requests that a self test or another specific test be
performed.
Chapter 22
SEND VOLUME TAG
(12 bytes)
B6h Compares the template it receives from the initiator
to the cartridge inventory information in memory,
and determines which bar code labels match the
template.
Chapter 23
TEST UNIT READY
(6 bytes)
00h Informs the initiator whether it is ready to accept all
other commands.
Chapter 24
WRITE BUFFER
(10 bytes)
3Bh Writes new microcode received from the initiator
into its flash EEPROM. The new microcode must be
sent in sections through multiple WRITE BUFFER
commands.
Chapter 25
Table 2-1 SCSI command set supported by the library (continued)
When you issue this
command …
OP
Code
The library does this … Discussed
in...
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