When the adapter rejects a command from the device driver, the reply IOCB in the data portion of the sense data will contain the reason code. Below are the documented reason that an adapter will reject a command.

Detail Data SENSE DATA 
NOTE:  Below is a portion of the AIX 5.3 and AIX 6.1 error templates.  
Click here to see full error template

AIX Version 5.3 and below

RRRR RRRR AAAA AAAA BBBB BBBB CCRR RRRR RRRR YYYY LLLL LLLL LLLL LLLL FFFF FFFF
QQQQ QQQQ QQQQ QQQQ QQQQ QQQQ QQQQ QQQQ GGGG GGGG OOOO OOOO OOOO OOOO EEEE EEEE
EEEE EEEE VVVV VVVV VVVV VVVV VVVV VVVV VVVV VVVV VVVV VVVV VVVV VVVV VVVV VVVV
VVVV VVVV TTTT TTTT TTTT TTTT TTTT TTTT TTTT TTTT RC TT TTT TTTT TTTT TTTT TTTT
...continued...

AIX Version 6.1 and above

hhhh hhhh AAAA AAAA BBBB BBBB CCtt vvvv YYYY YYYY LLLL LLLL LLLL LLLL FFFF FFFF
QQQQ QQQQ QQQQ QQQQ QQQQ QQQQ QQQQ QQQQ QQQQ QQQQ QQQQ QQQQ QQQQ QQQQ QQQQ QQQQ
GGGG GGGG pppp pppp OOOO OOOO OOOO OOOO EEEE EEEE EEEE EEEE ssss ssss ssss ssss
wwww wwww wwww wwww nnnn nnnn nnnn nnnn nnnn qqqq qqqq qqqq rrrr rrrr rrrr rrrr
MMNN PPSS UUWW XXZZ 11RR 2222 3333 3333 4444 4444 5555 5555 6666 6666 RRRR RRRR
7777 7777 8899 aabb cccc cccc dddd dddd eeee eeee ffgg iijj mmnn ooRR JJJJ uuuu
%%%% %%%% %%%% %%%% &&&& &&&& **** **** :::: :::: xxxx yyyy IIII IIII IIII IIII
VVVV .... continued..4 rows of VVVV
TTTT TTTT TTTT TTTT TTTT TTTT TTTT TTTT RCTT TTTT TTTT TTTT TTTT TTTT TTTT TTTT
....

Reason Code RC	IOERR	Description	What this means / What to do
0x01	MISSING_CONTINUE	Continue IOCB needed, but LE already seen	This is an AIX/System issue,
0x02	SEQUENCE_TIMEOUT	E_D_TOV time-out occurred.	This indicates in issue in the SAN, Contact AIX SAN support
0x03	INTERNAL_ERROR	Internal inconsistency discovered	This indicates an adapter detected issue. Review error log for FCS_ERR2 0x30
0x04	INVALID_RPI	Invalid RPI	The AIX device drive and adapter are out of sync on fibre channel login information, contact AIX SAN support.
0x05	NO_XRI	Specified XRI not in use	This indicates an AIX issue, Contact AIX SAN support.
0x06	ILLEGAL_COMMAND	Illegal Command in IOCB	This indicates an AIX, Contact AIX SAN support
0x07	XCHG_DROPPED	Data frame not completed when exchange goes away	Informational
0x08	ILLEGAL_FIELD	Bad BDE count or LE field	This indicates an AIX issue, Contact AIX SAN support.
0x0B	RCV_BUFFER_WAITING	Incoming sequence or partial sequence received without enough host receive buffers queued to ring	This indicates and issue with AIX, Contact AIX SAN support
0x0D	TX_DMA_FAILED	Error in transmit DMA path	This indicates a system or adapter problem Contact IOPE.
0x0E	RX_DMA_FAILED	Error in receive DMA path	This indicates a system or adapter problem Contact IOPE.
0x0F	ILLEGAL_FRAME	Many meanings: bad ACK_0(not end of sequence) data or ACK too far out of order duplicate frames ACK when not expecting one BA_ACC or BA_RJT received when not expecting one non XRF RDY when expecting one	This indicates a SAN issue, Contact your SAN fabric vendor for SAN/fabric hardware support.
0x11	NO_RESOURCES	Internal context full, or a maximum resources allocated with CONFIG_RING mailbox command	This indicates an AIX or an adapter firmware problem Contact IOPE.
0x13	ILLEGAL_LENGTH	FCP_CMD payload does not fit in a single frame	This indicates an AIX or an application issue, Contact AIX SAN support
0x14	UNSUPPORTED_FEATURE	Currently, used for SLI features not yet implemented	This indicates an AIX/application issue, Contact AIX SAN support.
0x15	ABORT_IN_PROGRESS	Exchange referenced is in the process of aborting	Informational,
0x16	ABORT_REQUESTED	Exchange referenced is being aborted due to local request	Informational
0x17	RCV_BUFFER_TIMEOUT	Frames of a sequence received into buffer SRAM have been discarded because enough host buffer or buffer list queued via QUE_RING_BUF64 / QUE_RING LIST64 were not available within E_D_TOV time-out.	This indicates an AIX/application issue, Contact AIX SAN support
0x18	LOOP_OPEN_FAILURE	The SLI Port sent an FC-AL OPN that was not responded to because the device addressed is no longer on the loop; it may have been removed or powered down	This indicates and end device issue, Contact AIX SAN support
0x19	RING_RESET	Command was aborted because of a RESET_RING mailbox command	Informational
0x1A	LINK_DOWN	Exchange referenced is being aborted due to either a link_down condition or a pending link attention status change	Do link down PD
0x1B	CORRUPTED_DATA	Exchange referenced is being aborted due to receive buffer overrun	This indicates a SAN, Contact AIX SAN support
0x1C	CORRUPTED_RPI	Exchange referenced is being aborted due to a corrupted RPI hardware context state	Contact IOPE
0x1D	OUT_OF_ORDER_DATA	Exchange referenced is being aborted due to the detection of an out of order frame that exceeded the SLI Port's reassembly threshold	This indicates a problem in the SAN, look for indications of dropped frames in the SAN, Contact AIX SAN support
0x1E	OUT_OF_ORDER_ACK	Exchange referenced is being aborted due to the detection of an out of order ACK that exceeded the SLI Port's reassembly threshold	This indicates a SAN issue, look for indications of bad transmission words, Contact your SAN fabric vendor for SAN/fabric hardware support.
0x1F	DUP_FRAME	Exchange referenced is being aborted due to the reception of a frame that has been detected as previously being processed.	This indicates a SAN issue, Contact your SAN fabric vendor for SAN/fabric hardware support.
0x20	LINK_CONTROL_FRAME	Exchange referenced is being aborted due to the reception of an ACKn or the reception of an ACK0 at the wrong time.	This indicates a SAN issue, Contact your SAN fabric vendor for SAN/fabric hardware support.
0x21	BAD_HOST_ADDRESS	Address out of range for 40-bit BDE format	This indicates an AIX issue, Contact AIX SAN support
0x25	ABORTMULT_REQUESTED	Command aborted by IO_TAG match	Informational
0x28	BUFFER_SHORTAGE	Freed buffers for point-to-point link reset	Informational, if this issue persists, contact IOPE.
0x29	RCV_XRIBUF_WAITING	Incoming sequence, or partial sequence, received without enough host receive buffers queued to XRI	This indicates an AIX issue, Contact AIX SAN support.
0x30	MISSING_XRIBUF	Frames of a sequence received into buffer SRAM have been discarded because enough host buffers or buffer lists queued to XRI were not available within E_D_TOV time-out	This indicates an AIX, Contact AIX SAN support
0x40	INVALID_RELOFFSET	Received frame with bad relative offset indicator	This indicates a SAN issue, Contact your SAN fabric vendor for SAN/fabric hardware support.
0x41	MISSING_RELOFFSET	Received frame without relative offset in frame header	This indicates a SAN issue, Contact your SAN fabric vendor for SAN/fabric hardware support.
0x42	INSUFF_BUFFSPACE	Insufficient buffer space to transfer all data	This indicates an AIX issue, Contact your SAN fabric vendor for SAN/fabric hardware support.
0x43	MISSING_SI	Received EndSequence frame without SequenceInitiative in frame header	This indicates a SAN issue, Contact your SAN fabric vendor for SAN/fabric hardware support.
0x44	MISSING_ES	Exhausted burst length without receiving EndSequence	-This indicates a SAN issue, Contact your SAN fabric vendor for SAN/fabric hardware support.
0x45	INCOMPLETE_XFER	Exhausted burst length with data still pending in frame	This indicates a SAN issue, Contact your SAN fabric vendor for SAN/fabric hardware support.

Adapter local Reason Codes