Maxtor ATLAS 10K III - Manual (Page 84)

SCSI Description
5-20 Maxtor Atlas 10K III
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The INQUIRY command allows the initiator to determine the kind of SCSI devices
attached to its SCSI bus. It causes a device that is attached to a SCSI bus to return
information about itself. The drive identifies itself as a Direct Access Storage Device
that implements the applicable interfacing protocol. The drive does not need to access
its storage medium to respond to the inquiry. The INQUIRY commands are
described in Table 5-22 and Table 5-23.
The drive can provide two categories of data in response to an INQUIRY command:
Standard Inquiry Data and Vital Product Data. Standard Inquiry Data contains basic
data about the drive, and Vital Product Data comprises several pages of additional data.
Each Vital Product Data page requires a separate INQUIRY command from the
initiator.
An INQUIRY command is not affected by, nor does it clear, a Unit Attention
condition.
Table 5-22 INQUIRY Command Descriptor Block-Data Format
Table 5-23
INQUIRY Command Descriptor Block-Field Descriptions
$KV
$[VG
       
0 Operation Code (12h)
1 Reserved CmdDt EVPD
2 Page Code or Operation Code
3 Reserved
4 Allocation Length
5 Control
(KGNF &GUETKRVKQP
CmdDt
Command Support Data. If CmdDt = 0 and EVPD (see below) = 0, the drive
returns the Standard Inquiry Data. If CmdDt = 1 with EVPD = 0, the drive
returns the Command Data specified by Page Code/Operation.
EVPD
Enable Vital Product Data. If EVPD = 0 and CmdDt (see above) = 0, the drive
returns the Standard Inquiry Data. If EVPD = 1and CmdDt = 0, the drive re-
turns the Vital Product Data Page specified by Page Code/Operation Code.
Page Code or
Operation Code
Specifies the Vital Product Data Page or Command Support Data which is to
be returned by the drive when EVPD is set. Specifies the SCSI Operation Code
for command support data to be returned by the drive when CmdDt is set. A
CHECK CONDITION status is returned if this field specifies an unsupported
Page or Operation Code or if both EVPD and CmdDt are set. Table 5-27 lists
the Page Codes for the Vital Product Pages supported by the drive. Table 5-
41 lists the operation codes for the CmdDt information supported by the
drive.
Allocation Length
Specifies the number of bytes of inquiry information the drive is allowed to
return to the initiator during the command's data-in buffer transfer. Error sta-
tus is not returned if the value in this field truncates the requested informa-
tion.