Windows 7 Home Premium 64-bit, Service Pack 1
I have a large collection of music, mostly ALAC (Apple Lossless) format. There are about 15,000 songs in about 1,600 folders, 339 GB in total.
I used Microsoft SyncToy to do a one-way (Echo) sync, which copies the files from my laptop to an external USB hard drive. Prior to syncing, I created a checksum of the entire folder.
After syncing, I verified checksums on the external drive copy, and it found errors. Checksum flagged 84 files as "CHANGED". When I compare Windows File Properties on the original and the external copy, the "Size" and "Size on disk" each have the same number
of bytes on the original and the copy.
But, there is something different, because when I try to play any of the "CHANGED" songs they hit a glitch partway through and stop playing. The original files play okay.
When I do a new Sync with Synctoy, it doesn't copy over any files because it detects that nothing has changed. So the file properties that Synctoy checks to see if something has changed must not show any change.
Any idea how the errors occurred during the SyncToy copy to the external drive, and how to identify them using Windows tools (since the File Properties I'm looking at don't show a difference)?
As the files clearly are different, since the failed-checksum music tracks don't play properly, why can't SyncToy detect that they are different?
How can I stop such errors from occurring? This has shaken my confidence in SyncToy, since SyncToy showed no errors but the files do have problems.