SCSI Primary Commands - 2.pdf

T10/1236-D Revision 20 18 July 2001available to the application client. Time-critical requirements are an implementation consideration and are notaddressed in this standard.7.3.5 Command support dataImplementation of command support data is optional. The application client may request the command supportdata information by setting the CMDDT bit to one and specifying the SCSI operation code of the desired CDB.If the device server implements the requested SCSI operation code, it shall return the data defined in table 55. Ifthe device server does not implement the requested SCSI operation code it shall return the peripheral qualifier andtype byte and 001b in the SUPPORT field.Table 55 — Command support data formatBitByte7 6 5 4 3 2 1 00 PERIPHERAL QUALIFIER PERIPHERAL DEVICE TYPE1 Reserved SUPPORT2 VERSION3 Reserved4 Reserved5 CDB SIZE (m - 5)6mCDB USAGE DATAThe PERIPHERAL QUALIFIER, the PERIPHERAL DEVICE TYPE, and the VERSION fields are defined in 7.3.2.Table 56 defines the values and meanings of the SUPPORT field.Table 56 — SUPPORT values and meaningsSupport000b001b010b011b100b101b110b111bDescriptionData about the requested SCSI operation code is not currently available.The device server does not support the tested SCSI operation code. All data afterbyte 1 is undefined.ReservedThe device server supports the tested SCSI operation code in conformance with aSCSI standard. The data format conforms to the definition in table 55.Vendor specificThe device server supports the tested SCSI operation code in a vendor specificmanner. The data format conforms to the definition in table 55.Vendor specificReservedIf the SUPPORT field contains 000b, all data after byte 1 is not valid. One possible reason for SUPPORT being 000b isthe device server's inability to retrieve information stored on the media. When this is the case, a subsequentrequest for command support data may be successful.92 dpANS SCSI Primary Commands - 2 (SPC-2)