Hitachi Ultrastar 15K450 (FC-AL) Hard Disk Drive Specification
107
18.2.2 FCP_XFER_RDY
The FCP_XFER_RDY IU indicates that the Target is prepared to perform all or part of the data transfer for a command.
During WRITE operations, the FCP_XFER_RDY IU indicates the amount of data that the Target expects from the Initiator.
Since the Target has planned buffer resources based on that amount of data, the Initiator is expected to provide exactly the
amount requested.
Table 93:FCP_XFER_RDY payload
The DATA_RO field indicates the contents of the RLTV_OFF field for the first data byte of the next FCP_DATA IU. The
RLTV_OFF field is part of the frame header.
The BURST_LEN field indicates the amount of buffer space prepared for the next FCP_DATA IU and requests an IU of that
exact length.
18.2.3 FCP_DATA
SCSI data transfers may be performed by one or more data delivery requests, each one performing a transfer no longer than the
maximum burst length defined by the parameters of the disconnect/reconnect mode page.
18.2.4 FCP_RSP
The content of the FCP_RSP IU is as shown in Table94.
Table 94:FCP_RSP payload
Byte Field Description Size (Bytes)
0-3 DATA_RO Relative Offset 4
4-7 BURST_LEN Length of FCP_DATA IU that follows 4
8-11 Reserved 4
Byte Field Description Size (Bytes)
0
-7
Reserved 8
8-11 FCP_STATUS Field Validity and SCSI Status 4
12-15 FCP_RESID Residual Count 4
16-19 FCP_SNS_LEN Length of FCP_SNS_INFO field 4
20-23 FCP_RSP_LEN Length of FCP_RSP_INFO field 4
24-> FCP_RSP_INFO FCP Response Information m
24+m-> FCP_SNS_INFO SCSI Sense Information n