File corruption: "sEDUsEDU" string in copied file

[Gerald Himmelein]

Version Info (principle, latest ver) : FastCopy ver3.86
OS/Environment : Windows 10, 64bit
Error Message / Logs: no message, no log
Error Details / Situations: "sEDUsEDU" in copied file
Specified Params : Diff (Size/Date), Buffer 128, Nonstop, Verify (xxHash)
Reproduction Steps : unknown

I have copied a number of large files from one hard drive to another, using FastCopy with the verify option (xxHash).

Before deleting one of the file sets, I checked with Beyond Compare for differences between the copied files. In theory, there shouldn't have been any. However, two files differed in content.

Initially, I thought that some bytes may have become corrupted and I suspected a hard drive defect.

Instead, I found that in one of the files, a rather significant block of bytes has been replaced by zero values and the string "sEDUsEDU" at fixed intervals. The range is suspicious as well: The corruption starts at byte position DD1DF000 and it ends at DD200000.

Only one of 94 files displays this error, but since this file is part of a large backup, it's a major issue for me.

Has anybody else ever come across something like this? Is it possible that this is a FastCopy bug?

Regards, Gerald

P.S.: See this screenshot from the hex view of Beyond Compare for an example of the discrepancy:

[SHIROUZU Hiroaki]

If you use verify option, the problem would be via source-read process. (not dest)

Can you confirm bus-reset or another hardware error in Source-HDD in Windows Event Viewer?

Now, FastCopy verify process is ... read-source and calc src-hash -> write-dest and read-dest and calc dst-hash -> compare src-hash and dst-hash.

If read-source is broken with hardware problem without API error, it can't detect the problem.

(read-souce twice and verify will be implement in the future, pro version or etc)

[SHIROUZU Hiroaki]

And can you confirm verify with FastCopy in the below steps?

Source: source-verify-error-file

DestDir: dest-verify-error-file's-parent-dir

CMD: non-overwrite

Push Listing button with Ctrl-key ("Listing" button will change "Listing-V" button)

https://fastcopy.jp/help/fastcopy_eng.htm#buttons

[Gerald Himmelein]

Thank you for your quick reply.

Before I start to dig any further: Can you please tell me if this weird string (sEDUsEDU) could have been generated by FastCopy?

If FastCopy can't have been the source, the cause must be elsewhere. If "sEDUsEDU" may have been generated by FastCopy, I will dig through my event logs and do everything I can to help find the cause of the problem.

Regards,

Gerald

[SHIROUZU Hiroaki]

FastCopy doesn't generates "sEDUsEDU".

And I don't have seen such data.

[Gerald Himmelein]

Thank you, that's what I needed to know. I must look elsewhere for the source of my file corruption.

Many thanks for clearing this up!