Inquiry Command (12H) - Seagate Ultra160 Product Manual

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8.6

INQUIRY command (12h)

The INQUIRY command requests that information regarding parameters of the target and a component logical
unit be sent to the application client. Options allow the application client to request additional information about
the target and logical unit or information about SCSI commands supported by the device server (see Section
8.6.3). Several INQUIRY commands may be sent to request the vital product data pages instead of the stan-
dard data shown in Table 79.
The INQUIRY command shall return CHECK CONDITION status only when the device server is unable to
return the requested INQUIRY data.
Table 78: INQUIRY command (12h)
Bit 7
Byte
0 0
1
2 PAGE OR OPERATION CODE [3]
3 Reserved
4 ALLOCATION LENGTH IN BYTES [4]
5 CONTROL [5]
[1] An Enable Vital Product Data (EVPD) bit of one specifies that the device server shall return the optional
vital product data specified by the PAGE OR OPERATION CODE field. If the logical unit does not support
vital product data and this bit is set to one, the device server shall return CHECK CONDITION status with
the sense key set to ILLEGAL REQUEST and an additional sense code of Invalid Field in CDB.
[2] A Command Support Data (CMDDT) bit of one specifies that the device server shall return the optional
command support data specified by the Page or OPERATION CODE field. If the device server does not
support returning command data and this bit is set to one, the device server shall return CHECK CONDI-
TION status with the sense key set to ILLEGAL REQUEST and an additional sense code of Invalid Field
in CDB. Details of the command support data may be found in Section 8.6.4.
Note. A SCSI application client may receive a CHECK CONDITION status response with the sense key set
to ILLEGAL REQUEST upon sending an INQUIRY command with the CMDDT bit set to 1 to some
SCSI-2 device servers, since this bit was reserved in SCSI-2.
If both the EVPD and CMDDT bits are zero, the device server shall return the standard INQUIRY data
(see Section 8.6.1). If the Page or OPERATION CODE field is not zero when both EVPD and CMDDT are
zero, the device server shall return CHECK CONDITION status with the sense key set to ILLEGAL
REQUEST and an additional sense code of Invalid Field in CDB.
If both the EVPD and CMDDT bits are one, the device server shall return CHECK CONDITION status with
the sense key set to ILLEGAL REQUEST and an additional sense code of Invalid Field in CDB. When the
EVPD bit is one, the Page or OPERATION CODE field specifies which page of vital product data informa-
tion the device server shall return (see Section 8.6.3).
When the CMDDT bit is one, the PAGE OR OPERATION CODE field specifies the SCSI operation code
for which device server shall return command support data (see Section 8.6.4).
[3] The PAGE OR OPERATION CODE field specifies the page of vital product data information that the drive
shall return. If the EVPD bit is zero and the page code field is not zero the drive shall return CHECK CON-
DITION status with the sense key set to ILLEGAL REQUEST and an additional sense code of Invalid Field
in CDB.
[4] The ALLOCATION LENGTH specifies the number of bytes that the initiator has allocated for returned
data. The drive shall terminate the DATA IN phase when ALLOCATION LENGTH bytes have been trans-
ferred or when all available data have been transferred to the initiator, whichever is less.
[5] See Table 61, "CONTROL field," in Section 7.2.1.
6 5
0 0
Reserved
SCSI Interface Product Manual, Rev. B
4 3
1 0
2 1
0 1
CMDDT [2] EVPD [1]
0
0