File verification during synchronization

Discuss new features and functions
Posts: 3
Joined: 29 Apr 2019

Post by Paramonte • 29 Apr 2019, 20:12

I am a new user of FreeFileSync.

I am doing synchronization from a folder in my Desktop do a folder in google drive.

Is there any way to verify that the copied files in my google drive folder are exactly the same as the original files in my desktop folder. It took about 3 days to perform my 1.5 Tera Byte data synchronization to the google drive.

Of course I can use the compare function (with contents compare activated) but that is equivalent to duplicate the processing time (more about 3 days of processing to compare).

is there a way of comparing the original and copied files during the synchronization process, on the fly, via hash (file checksum) or whatever?

Thanks in Advance

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Posts: 707
Joined: 22 Aug 2012

Post by Plerry • 30 Apr 2019, 07:06

In the Expert Settings you can set the VerifyCopiedFiles flag to "true".
However, this means that uploaded data needs to be downloaded again to be compared to the local version, so it will cost a substantial amount of extra time.

Also be sure to read the link to "Does the CopyFile function verify that the data reached its final destination successfully?" You may be comparing cashed data, instead of data as read from disk.

Several users have suggested to use checksums.
However, the use of checksums only makes sense if the checksum check is run locally to where the files are stored.
If you first need to download the data from a remote location to your local machine running the FFS sync to perform the checksum check, you may just as well compare on full content; the download is then the limiting factor.