MAX filesize for the Synchronize Compare


I wanted to compare 2 folders containing a bunch of subfolders with DVD images (lots of 0.99GB files) after having copied them over from one disk to another.
The compare finished in about 1/2 a second, stating that everything is perfectly equal although it is set to byte-comparison.

So, DO falsely reports that everything is equal while it doesn't even look at them.

Therefor, what is the maximum size DO will do a byte-comparison, so people don't get cheated into believing 2 files are the same while they aren't ?

The limit you speak of does not seem to exist for me, at least in the 64-bit version of Opus.

I copied three large files and modified the copies using a hex editor, so they were still the same size but had a few bytes different. I made sure to edit bytes right at the end of the files in two cases, and in the middle of the other file, so that if Opus stopped comparing them half-way through then it would consider them equal.

Opus compared the file contents (I could tell since it took a while to process them) and noticed that all three files were different:

Since you're using 32-bit Opus it's possible there is an overflow somewhere, but that seems unlikely given that the files you mention are only 0.99GB in size. If they were more towards 2GB or 4GB in size then there might be something to investigate there, since that's when signed and unsigned 32-bit numbers wrap around, but with 0.99GB files (and Opus being written to use 64-bit filesizes even in the 32-bit version) I doubt that would be the cause of the problem.

Please provide full details on the sync you are doing. For example, are you using a filter? What settings are in the sync panel? etc.

Hi Leo, yes I'm using the 32bit version.
This is how my Synchronize window looks like :

Without seeing details of the files/folders being synced I can only guess, but Syncronize sub-folder contents is off in your screenshot. Are the files in question directly below the two starting folders, or are they in sub-folders?

Ah thanks,
It was indeed the "Sync sub-folder contents" that was unchecked. Doh!