Key Code Qualifier
Key Code Qualifier is a computer term used to describe an error-code returned by a SCSI device.
When a SCSI target device returns a check condition in response to a command, the initiator usually then issues a SCSI Request Sense command. This process is part of a SCSI protocol called Contingent Allegiance Condition. The target will respond to the Request Sense command with a set of SCSI sense data which includes three fields giving increasing levels of detail about the error:
- K - sense key - 4 bits
- C - additional sense code (ASC) - 8 bits
- Q - additional sense code qualifier (ASCQ) - 8 bits
The initiator can take action based on just the K field which indicates if the error is minor or major. However all three fields are usually logically combined into a 20 bit field called Key Code Qualifier or KCQ. The specification for the target device will define the list of possible KCQ values. In practice there are many KCQ values which are common between different SCSI device types and different SCSI device vendors.
List of common SCSI KCQs
| Category | Key | ASC | ASCQ | Error Condition |
|---|---|---|---|---|
| No Sense | 0 | 00 | 00 | No error |
| 0 | 5D | 00 | No sense - PFA threshold reached | |
| Soft Error | 1 | 01 | 00 | Recovered Write error - no index |
| 1 | 02 | 00 | Recovered no seek completion | |
| 1 | 03 | 00 | Recovered Write error - write fault | |
| 1 | 09 | 00 | Track following error | |
| 1 | 0B | 01 | Temperature warning | |
| 1 | 0C | 01 | Recovered Write error with auto-realloc - reallocated | |
| 1 | 0C | 03 | Recovered Write error - recommend reassign | |
| 1 | 12 | 01 | Recovered data without ECC using prev logical block ID | |
| 1 | 12 | 02 | Recovered data with ECC using prev logical block ID | |
| 1 | 14 | 01 | Recovered Record Not Found | |
| 1 | 16 | 00 | Recovered Write error - Data Sync Mark Error | |
| 1 | 16 | 01 | Recovered Write error - Data Sync Error - data rewritten | |
| 1 | 16 | 02 | Recovered Write error - Data Sync Error - recommend rewrite | |
| 1 | 16 | 03 | Recovered Write error - Data Sync Error - data auto-reallocated | |
| 1 | 16 | 04 | Recovered Write error - Data Sync Error - recommend reassignment | |
| 1 | 17 | 00 | Recovered data with no error correction applied | |
| 1 | 17 | 01 | Recovered Read error - with retries | |
| 1 | 17 | 02 | Recovered data using positive offset | |
| 1 | 17 | 03 | Recovered data using negative offset | |
| 1 | 17 | 05 | Recovered data using previous logical block ID | |
| 1 | 17 | 06 | Recovered Read error - without ECC, auto reallocated | |
| 1 | 17 | 07 | Recovered Read error - without ECC, recommend reassign | |
| 1 | 17 | 08 | Recovered Read error - without ECC, recommend rewrite | |
| 1 | 17 | 09 | Recovered Read error - without ECC, data rewritten | |
| 1 | 18 | 00 | Recovered Read error - with ECC | |
| 1 | 18 | 01 | Recovered data with ECC and retries | |
| 1 | 18 | 02 | Recovered Read error - with ECC, auto reallocated | |
| 1 | 18 | 05 | Recovered Read error - with ECC, recommend reassign | |
| 1 | 18 | 06 | Recovered data using ECC and offsets | |
| 1 | 18 | 07 | Recovered Read error - with ECC, data rewritten | |
| 1 | 1C | 00 | Defect List not found | |
| 1 | 1C | 01 | Primary defect list not found | |
| 1 | 1C | 02 | Grown defect list not found | |
| 1 | 1F | 00 | Partial defect list transferred | |
| 1 | 44 | 00 | Internal target failure | |
| 1 | 5D | 00 | PFA threshold reached | |
| 1 | 5D | FF | PFA test warning | |
| 1 | 81 | 00 | Internal logic failure | |
| Not Ready | 2 | 04 | 00 | Not Ready - start motor failed |
| 2 | 04 | 01 | Not Ready - becoming ready | |
| 2 | 04 | 02 | Not Ready - need initialise command (start unit) | |
| 2 | 04 | 03 | Not Ready - manual intervention required | |
| 2 | 04 | 04 | Not Ready - format in progress | |
| 2 | 04 | 09 | Not Ready - self-test in progress | |
| 2 | 31 | 00 | Not Ready - medium format corrupted | |
| 2 | 31 | 01 | Not Ready - format command failed | |
| 2 | 35 | 02 | Not Ready - enclosure services unavailable | |
| 2 | 40 | 80 | Diagnostic Failure - bring-up fail or degraded mode | |
| 2 | 40 | 81 | Diagnostic Failure - Hard Disk Controller | |
| 2 | 40 | 85 | Diagnostic Failure - RAM microcode not loaded | |
| 2 | 40 | 90 | Diagnostic Failure - RRO Calibration | |
| 2 | 40 | 91 | Diagnostic Failure - Channel Calibration | |
| 2 | 40 | 92 | Diagnostic Failure - Head Load | |
| 2 | 40 | 93 | Diagnostic Failure - Write AE | |
| 2 | 40 | 94 | Diagnostic Failure - 12V over current | |
| 2 | 40 | 95 | Diagnostic Failure - Other spindle failure | |
| 2 | 40 | B0 | Diagnostic Failure - self-reset | |
| 2 | 4C | 00 | Diagnostic Failure - config not loaded |
Medium 3 03 00 Medium Error - write fault Error 3 0C FF Medium Error - write recovery time limit exceeded 3 10 00 Medium Error - ID CRC error 3 11 00 Medium Error - unrecovered read error 3 11 01 Medium Error - read retries exhausted 3 11 02 Medium Error - error too long to correct 3 11 04 Medium Error - unrecovered read error - auto re-alloc failed 3 11 0B Medium Error - unrecovered read error - recommend reassign 3 11 FF Medium Error - read recovery time limit exceeded 3 14 01 Medium Error - record not found 3 16 00 Medium Error - Data Sync Mark error 3 16 04 Medium Error - Data Sync Error - recommend reassign 3 19 00 Medium Error - defect list error 3 19 01 Medium Error - defect list not available 3 19 02 Medium Error - defect list error in primary list 3 19 03 Medium Error - defect list error in grown list 3 19 0E Medium Error - fewer than 50% defect list copies 3 31 00 Medium Error - medium format corrupted 3 31 01 Medium Error - format command failed 3 80 00 Medium Error - data auto-reallocated Hardware 4 01 00 Hardware Error - no index or sector Error 4 02 00 Hardware Error - no seek complete 4 03 00 Hardware Error - write fault 4 09 00 Hardware Error - track following error 4 11 00 Hardware Error - unrecovered read error in reserved area 4 16 00 Hardware Error - Data Sync Mark error in reserved area 4 19 00 Hardware Error - defect list error 4 19 02 Hardware Error - defect list error in Primary List 4 19 03 Hardware Error - defect list error in Grown List 4 31 00 Hardware Error - reassign failed 4 32 00 Hardware Error - no defect spare available 4 35 01 Hardware Error - unsupported enclosure function 4 35 02 Hardware Error - enclosure services unavailable 4 35 03 Hardware Error - enclosure services transfer failure 4 35 04 Hardware Error - enclosure services refused 4 3E 03 Hardware Error - self-test failed 4 3E 04 Hardware Error - unable to update self-test 4 40 80 Hardware Error - Degrade Mode. Diagnostic Fail. 4 40 81 Hardware Error - Degrade Mode. H/W Error 4 40 85 Hardware Error - Degrade Mode. RAM microcode not loaded. 4 40 90 Hardware Error - seek test failure 4 40 A0 Hardware Error - read/write test failure 4 40 B0 Hardware Error - device self-reset 4 40 D0 Hardware Error - component mismatch 4 44 00 Hardware Error - internal target failure 4 81 00 Hardware Error - internal logic error 4 82 00 Hardware Error - command timeout Illegal 5 1A 00 Illegal Request - parm list length error Request 5 20 00 Illegal Request - invalid/unsupported command code 5 21 00 Illegal Request - LBA out of range 5 24 00 Illegal Request - invalid field in CDB 5 25 00 Illegal Request - invalid LUN 5 26 00 Illegal Request - invalid fields in parm list 5 26 01 Illegal Request - parameter not supported 5 26 02 Illegal Request - invalid parm value 5 26 03 Illegal Request - invalid field parameter - threshold parameter 5 26 04 Illegal Request - invalid release of persistent reservation 5 26 97 Illegal Request - invalid field parameter - TMS firmware tag 5 26 98 Illegal Request - invalid field parameter - check sum 5 26 99 Illegal Request - invalid field parameter - firmware tag 5 2C 00 Illegal Request - command sequence error 5 35 01 Illegal Request - unsupported enclosure function 5 49 00 Illegal Request - invalid message 5 55 00 Illegal Request - system resource failure 5 55 01 Illegal Request - system buffer full 5 55 04 Illegal Request - Insufficient Registration Resources Unit 6 28 00 Unit Attention - not-ready to ready transition (format complete) Attention 6 29 00 Unit Attention - POR or device reset occurred 6 29 01 Unit Attention - POR occurred 6 29 02 Unit Attention - SCSI bus reset occurred 6 29 03 Unit Attention - TARGET RESET occurred 6 29 04 Unit Attention - self-initiated-reset occurred 6 29 05 Unit Attention - transceiver mode change to SE 6 29 06 Unit Attention - transceiver mode change to LVD 6 2A 00 Unit Attention - parameters changed 6 2A 01 Unit Attention - mode parameters changed 6 2A 02 Unit Attention - log select parms changed 6 2A 03 Unit Attention - Reservations pre-empted 6 2A 04 Unit Attention - Reservations released 6 2A 05 Unit Attention - Registrations pre-empted 6 2F 00 Unit Attention - commands cleared by another initiator 6 3F 00 Unit Attention - target operating conditions have changed 6 3F 01 Unit Attention - microcode changed 6 3F 02 Unit Attention - changed operating definition 6 3F 03 Unit Attention - inquiry parameters changed 6 3F 05 Unit Attention - device identifier changed 6 3F 90 Unit Attention - invalid APM parameters 6 3F 91 Unit Attention - world-wide name mismatch 6 5D 00 Unit Attention - PFA threshold reached 6 5D FF Unit Attention - PFA threshold exceeded Write 7 27 00 Write Protect - command not allowed Protect Aborted B 00 00 Aborted Command - no additional sense code Command B 1B 00 Aborted Command - sync data transfer error (extra ACK) B 25 00 Aborted Command - unsupported LUN B 3F 0F Aborted Command - echo buffer overwritten B 43 00 Aborted Command - message reject error B 44 00 Aborted Command - internal target failure B 45 00 Aborted Command - Selection/Reselection failure B 47 00 Aborted Command - SCSI parity error B 48 00 Aborted Command - initiator-detected error message received B 49 00 Aborted Command - inappropriate/illegal message B 4B 00 Aborted Command - data phase error B 4E 00 Aborted Command - overlapped commands attempted B 4F 00 Aborted Command - due to loop initialisation Other E 1D 00 Miscompare - during verify byte check operation x 03 86 Write Fault Data Corruption x 05 00 Illegal request x 06 00 Unit attention x 07 00 Data protect x 08 00 LUN communication failure x 08 01 LUN communication timeout x 08 02 LUN communication parity error x 09 00 vendor specific sense key x 09 01 servo fault x 09 04 head select fault x 0A 00 error log overflow x 0B 00 aborted command x 0C 00 write error x 0C 02 write error - auto-realloc failed x 0E 00 data miscompare x 12 00 address mark not founf for ID field x 14 00 logical block not found x 15 00 random positioning error x 15 01 mechanical positioning error x 15 02 positioning error detected by read of medium x 27 00 write protected x 29 00 POR or bus reset occurred x 31 01 format failed x 31 91 format corrupted x 32 01 defect list update error x 32 02 no spares available x 35 01 unspecified enclosure services failure x 37 00 parameter rounded x 3D 00 invalid bits in identify message x 3E 00 LUN not self-configured yet x 40 01 DRAM parity error x 40 02 DRAM parity error x 42 00 power-on or self-test failure x 4C 00 LUN failed self-configuration x 5C 00 RPL status change x 5C 01 spindles synchronised x 5C 02 spindles not synchronised x 65 00 voltage fault x 80 00 general firmware error