9.5.11 SCSI STATUS CODE field

The SCSI STATUS CODE field contains the status code for the SCSI command being completed, as defined by SAM-3.

9.5.12FCP_RESID field

For read operations and write operations, if the FCP_RESID_UNDER bit is set to one, the FCP_RESID field contains a count of the number of residual data bytes that were not transferred in FCP_DATA IUs.

For read operations and write operations, if the FCP_RESID_OVER bit is set to one, the FCP_RESID field contains the excess of the number of bytes required by the SCSI command to be transferred over the number of bytes specified by the FCP_DL field.

For bidirectional SCSI commands, if the FCP_RESID_UNDER bit is set to one, the FCP_RESID field contains a count of the number of residual data bytes that were not transferred in the Data-Out FCP_DATA IUs for the command.

For bidirectional SCSI commands, if the FCP_RESID_OVER bit is set to one, the FCP_RESID field contains the excess of the number of bytes required to be transferred in the Data-Out FCP_DATA IUs by the command over the number of bytes specified in the FCP_DL field.

For bidirectional SCSI commands, the FCP_BIDIRECTIONAL_READ_RESID field (see 9.5.13) contains the corresponding count for Data-In FCP_DATA IUs.

Upon successful completion of an FCP I/O operation, the residual value is normally zero and the FCP_RESID value is not valid. FCP devices having indeterminate data lengths may have a nonzero residual byte count after completing valid operations. There is no requirement to verify that the data length implied by the contents of the CDB does not cause an overrun or underrun before beginning the processing of a SCSI command.

If the FCP_RESID_UNDER bit is set to one, a transfer that did not fill the buffer to the expected displacement FCP_DL was performed and the value of FCP_RESID is defined as follows:

FCP_RESID = FCP_DL - (highest offset of any byte transmitted + 1)

A condition of FCP_RESID_UNDER may not be an error for some FCP devices and some commands.

If the FCP_RESID_OVER bit is set to one, refer to 9.4.2 or 9.4.3. The FCP_RESID value is defined as follows:

FCP_RESID = (transfer length required by command) - FCP_DL

If the FCP_RESID_UNDER and the FCP_RESID_OVER bits are set to zero, the FCP_RESID field is not meaningful and may have any value. The FCP_RESID field is always included in the FCP_RSP IU.

NOTE 6 - Some early implementations presented the FCP_RSP IU without the FCP_RESID, FCP_SNS_LEN, and

FCP_RSP_LEN fields if the FCP_RESID_UNDER, FCP_RESID_OVER, FCP_SNS_LEN_VALID, and FCP_RSP_LEN_VALID bits were all set to zero. This non-standard behavior should be tolerated.

9.5.13FCP_BIDIRECTIONAL_READ_RESID field

The FCP_BIDIRECTIONAL_READ_RESID field is included in the FCP_RSP IU for all bidirectional SCSI commands.

For bidirectional commands, if the FCP_BIDI_READ_RESID_UNDER bit is set to one, the FCP_BIDIRECTIONAL_READ_RESID field contains a count of the number of residual data bytes that were not transferred in Data-In FCP_DATA IUs.

For bidirectional commands, if the FCP_BIDI_READ_RESID_OVER bit is set to one, the FCP_BIDIRECTIONAL_READ_RESID field contains the excess of the number of bytes required by the command to be transferred in Data-In FCP_DATA IUs over the number of bytes specified by the FCP_BIDIRECTIONAL_READ_DL field.

Upon successful completion of an FCP I/O operation, the residual value is normally zero and the FCP_BIDIRECTIONAL_READ_RESID value is not valid. FCP devices having indeterminate data lengths may have a nonzero residual byte count after completing valid operations. There is no requirement to verify that the data length implied by the contents of the CDB does not cause an overrun or underrun before beginning the processing of a SCSI command.

If the FCP_BIDI_READ_RESID_UNDER bit is set to one, a transfer that did not fill the buffer to the expected displacement FCP_BIDIRECTIONAL_READ_DL was performed and the value of FCP_BIDIRECTIONAL_READ_RESID is defined as follows:

FCP_BIDIRECTIONAL_READ_RESID = FCP_BIDIRECTIONAL_READ_DL - (highest offset of any byte transmitted + 1)

A condition of FCP_BIDI_READ_RESID_UNDER may not be an error for some FCP devices and some commands.

If the FCP_BIDI_READ_RESID_OVER bit is set to one, refer to 9.4.3. The FCP_BIDIRECTIONAL_READ_RESID value is defined as follows:

FCP_BIDIRECTIONAL_READ_RESID = (read transfer length required by command) -

FCP_BIDIRECTIONAL_READ_DL

If the FCP_BIDI_READ_RESID_UNDER and the FCP_RESID_OVER bits are both set to zero, the FCP_BIDIRECTIONAL_READ_RESID field is not meaningful and may have any value.

9.5.14FCP_SNS_LEN field

If the FCP_SNS_LEN_VALID bit is one, the FCP_SNS_LEN field specifies the number of valid bytes of FCP_SNS_INFO.

If the FCP_SNS_LEN_VALID bit is zero, the FCP_SNS_LEN field is not valid and shall be treated as if its value were zero. No FCP_SNS_INFO is provided.

The FCP_SNS_LEN field is always included in the FCP_RSP IU.

9.5.15FCP_RSP_LEN field

If the FCP_RSP_LEN_VALID bit is one, the FCP_RSP_LEN field specifies the number of valid bytes of FCP_RSP_INFO. The number shall be 00000004h, or 00000008h.

If the FCP_RSP_LEN_VALID bit is zero, the FCP_RSP_LEN field is not valid and shall be treated as if its value were zero. No FCP_RSP_INFO is provided.

The FCP_RSP_LEN field is always included in the FCP_RSP IU.

9.5.16FCP_RSP_INFO field

The FCP_RSP_INFO field contains information describing only the protocol failures detected during the processing of an FCP I/O operation. If none of the specified protocol failures have occurred, the FCP_RSP_INFO field shall not be included in the FCP_RSP IU and the FCP_RSP_LEN_VALID bit shall be zero. The FCP_RSP_INFO does not contain link error information, since FC-FS-2 provides the mechanisms for presenting such errors. The FCP_RSP_INFO field does not contain SCSI logical unit error information, since that is contained in the FCP_SNS_INFO field as described in 9.5.17. The FCP_RSP_INFO field shall contain valid information if the target

FCP_Port detects any of the conditions indicated by an FCP RSP_CODE. The format of the FCP_RSP_INFO field is specified in table 23.

Table 23 - FCP_RSP_INFO field format

The valid RSP_CODE values are specified in table 24.

a Only valid when responding to task management functions,

The completion status of the task management function is indicated by the RSP_CODE. If the Exchange is aborted before the FCP_RSP IU is returned, the completion status is unknown. If the RSP_CODE is set to 05h (i.e., Task Management function failed), the state of the logical unit is unknown.

Activities started by a task management function may continue after the FCP_RSP IU for the task management has been delivered.

9.5.17FCP_SNS_INFO field

The FCP_SNS_INFO field contains the autosense data specified by SPC-3. The proper FCP_SNS_INFO shall be presented when the SCSI status byte of CHECK CONDITION is presented as specified by SAM-3. If no conditions requiring the presentation of SCSI sense data have occurred, the FCP_SNS_INFO field shall not be