Seagate Ultra160 Product Manual page 175

SCSI Interface Product Manual, Rev. B
[2] Table 88 defines the values and meanings of the SUPPORT field.
Table 88: Support values and meanings
Support Description
000b Data about the requested SCSI operation is not currently available.
001b The device server does not support the tested SCSI operation code. All data after byte 1 is
undefined.
010b Reserved.
011b The device server supports the tested SCSI operation code in conformance with an SCSI
standard. The data format conforms to the definition in Table 87.
100b vendor-specific.
101b The device server supports the tested SCSI operation code in a vendor-specific manner. The
data format conforms to the definition in Table 87.
110b vendor-specific.
111b Reserved.
If the SUPPORT field contains 000b, all data after byte 1 is not valid. One possible reason for SUPPORT
being 000b is the device server's inability to retrieve information stored on the media. When this is the
case, a subsequent request for command support data may be successful.
[3] VERSION. See Table 79.
[4] The CDB SIZE field shall contain the number of bytes in the CDB for the operation code being queried,
and the size of the CDB USAGE DATA field in the return data.
Note. The CDB SIZE field is provided primarily for the convenience of the application client. In most
cases, the size is known from the operation code group.
The CDB USAGE DATA field shall contain information about the CDB for the operation code being que-
ried. The first byte of the CDB usage data shall contain the operation code for the operation being queried.
All bytes except the first byte of the CDB usage data shall contain a usage map for bits in the CDB for the
operation code being queried.
The bits in the usage bit map have a one-for-one correspondence to the CDB for the operation code being
queried. If the device server evaluates a bit as all or part of a field in the CDB for the operation code being
queried, the usage map shall contain a one in the corresponding bit position. If the device server ignores
or treats as reserved a bit in the CDB for the operation code being queried, the usage map shall contain a
zero in the corresponding it position. The usage map bits for a given CDB field all shall have the same
value.
Thus, the CDB usage bit map for the INQUIRY command for a device server that implements command
support data but not vital product data is: 12h, 02h, FFh, 00h, FFh, 07h. This example assumes that SAM-
2 defines uses for only the low-order three bits of the Control byte. Note that the first byte contains the
operation code and the remaining bytes contain the usage map.
157