SCSI ASC/ASCQ 摘述
前言
前两篇 SCSI相关文章如下，结合本文基本可以快速定位 SCSI相关的问题。例如 U盘、移动硬盘热插拔不识别、读写文件失败或是读写引起 USB disconnect的问题。
正文
出现 SCSI相关错误的时候，我们总能看到下面这样的 log。
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log里面的关键词是 ASC和 ASCQ，大概的意思是：
ASC（ADDITIONAL SENSE CODE），附加检测码，用来描述 sense key报告的错误或者异常情况的更多信息，如果设备没有错误或者异常情况，则附加检测码应该设置为零。
ASCQ（ADDITIONAL SENSE CODE QUALIFIER），附加检测码的限定符，用来描述与附加检测码相关的详细信息，如果设备没有错误或者异常情况，则附加检测码的限定符应该设置为零。
在 log中 ASC=0x28、ASCQ=0x0，通过查表确定 sense key报告的详细信息是 NOT READY TO READY CHANGE, MEDIUM MAY HAVE CHANGED，大概意思 U盘中的存储介质发生了改变，即 U盘主控还在，但储存介质出现异常，主控无法对储存介质进行读写。例如出现了 U盘主控与介质通信部分的软件或者逻辑异常、介质命令阻塞、遇到坏块等问题，当然具体原因还是要根据实际应用场景分析。
附表
ASC值对应的具体含义如下，ASCQ值对应的具体含义可以跟随链接，在 t10.org了解，或是查询 SCSI Commands Reference Manual –> 2.4.1.6 Additional Sense and Additional Sense Qualifier codes。
00h/00h NO ADDITIONAL SENSE INFORMATION
01h/00h NO INDEX/SECTOR SIGNAL
03h/00h PERIPHERAL DEVICE WRITE FAULT
04h/00h LOGICAL UNIT NOT READY, CAUSE NOT REPORTABLE
05h/00h LOGICAL UNIT DOES NOT RESPOND TO SELECTION
06h/00h NO REFERENCE POSITION FOUND
07h/00h MULTIPLE PERIPHERAL DEVICES SELECTED
08h/00h LOGICAL UNIT COMMUNICATION FAILURE
0Dh/00h ERROR DETECTED BY THIRD PARTY TEMPORARY INITIATOR
0Eh/00h INVALID INFORMATION UNIT
11h/00h UNRECOVERED READ ERROR
12h/00h ADDRESS MARK NOT FOUND FOR ID FIELD
13h/00h ADDRESS MARK NOT FOUND FOR DATA FIELD
14h/00h RECORDED ENTITY NOT FOUND
15h/00h RANDOM POSITIONING ERROR
16h/00h DATA SYNCHRONIZATION MARK ERROR
17h/00h RECOVERED DATA WITH NO ERROR CORRECTION APPLIED
18h/00h RECOVERED DATA WITH ERROR CORRECTION APPLIED
1Ah/00h PARAMETER LIST LENGTH ERROR
1Bh/00h SYNCHRONOUS DATA TRANSFER ERROR
1Dh/00h MISCOMPARE DURING VERIFY OPERATION
1Eh/00h RECOVERED ID WITH ECC CORRECTION
1Fh/00h PARTIAL DEFECT LIST TRANSFER
20h/00h INVALID COMMAND OPERATION CODE
21h/00h LOGICAL BLOCK ADDRESS OUT OF RANGE
22h/00h ILLEGAL FUNCTION (USE 20 00, 24 00, OR 26 00)
23h/00h INVALID TOKEN OPERATION, CAUSE NOT REPORTABLE
25h/00h LOGICAL UNIT NOT SUPPORTED
26h/00h INVALID FIELD IN PARAMETER LIST
28h/00h NOT READY TO READY CHANGE, MEDIUM MAY HAVE CHANGED
29h/00h POWER ON, RESET, OR BUS DEVICE RESET OCCURRED
2Bh/00h COPY CANNOT EXECUTE SINCE HOST CANNOT DISCONNECT
2Ch/00h COMMAND SEQUENCE ERROR
2Dh/00h OVERWRITE ERROR ON UPDATE IN PLACE
2Eh/00h INSUFFICIENT TIME FOR OPERATION
2Fh/00h COMMANDS CLEARED BY ANOTHER INITIATOR
30h/00h INCOMPATIBLE MEDIUM INSTALLED
31h/00h MEDIUM FORMAT CORRUPTED
32h/00h NO DEFECT SPARE LOCATION AVAILABLE
35h/00h ENCLOSURE SERVICES FAILURE
36h/00h RIBBON, INK, OR TONER FAILURE
38h/00h EVENT STATUS NOTIFICATION
39h/00h SAVING PARAMETERS NOT SUPPORTED
3Bh/00h SEQUENTIAL POSITIONING ERROR
3Dh/00h INVALID BITS IN IDENTIFY MESSAGE
3Eh/00h LOGICAL UNIT HAS NOT SELF-CONFIGURED YET
3Fh/00h TARGET OPERATING CONDITIONS HAVE CHANGED
40h/00h RAM FAILURE (SHOULD USE 40 NN)
41h/00h DATA PATH FAILURE (SHOULD USE 40 NN)
42h/00h POWER-ON OR SELF-TEST FAILURE (SHOULD USE 40 NN)
44h/00h INTERNAL TARGET FAILURE
45h/00h SELECT OR RESELECT FAILURE
46h/00h UNSUCCESSFUL SOFT RESET
48h/00h INITIATOR DETECTED ERROR MESSAGE RECEIVED
4Ch/00h LOGICAL UNIT FAILED SELF-CONFIGURATION
4Eh/00h OVERLAPPED COMMANDS ATTEMPTED
53h/00h MEDIA LOAD OR EJECT FAILED
54h/00h SCSI TO HOST SYSTEM INTERFACE FAILURE
55h/00h SYSTEM RESOURCE FAILURE
57h/00h UNABLE TO RECOVER TABLE-OF-CONTENTS
58h/00h GENERATION DOES NOT EXIST
5Ah/00h OPERATOR REQUEST OR STATE CHANGE INPUT
5Dh/00h FAILURE PREDICTION THRESHOLD EXCEEDED
5Eh/00h LOW POWER CONDITION ON
61h/00h VIDEO ACQUISITION ERROR
62h/00h SCAN HEAD POSITIONING ERROR
63h/00h END OF USER AREA ENCOUNTERED ON THIS TRACK
64h/00h ILLEGAL MODE FOR THIS TRACK
66h/00h AUTOMATIC DOCUMENT FEEDER COVER UP
68h/00h LOGICAL UNIT NOT CONFIGURED
69h/00h DATA LOSS ON LOGICAL UNIT
6Ah/00h INFORMATIONAL, REFER TO LOG
6Bh/00h STATE CHANGE HAS OCCURRED
6Ch/00h REBUILD FAILURE OCCURRED
6Dh/00h RECALCULATE FAILURE OCCURRED
6Eh/00h COMMAND TO LOGICAL UNIT FAILED
6Fh/00h COPY PROTECTION KEY EXCHANGE FAILURE - AUTHENTICATION FAILURE
71h/00h DECOMPRESSION EXCEPTION LONG ALGORITHM ID