FreeFileSync Forum

... to upgrade them.
==> Fetching downloads for: freefilesync
✘ Cask freefilesync (14.6) [Verifying 30.9MB/ 30.9MB]
Error: Cask reports different checksum: 78f81bcdc00550526aac935a992ed4bca653e44a9136afaff534660408b7f099
SHA-256 checksum of downloaded file ...

... drive has cluster size bigger than the sync.ffs_db file itself, the FFS fills the remaining empty space with 0x00, which then produces CRC error.

Cannot read database file "path\to\sync.ffs_db".
File content is corrupted. (invalid checksum)

I'm using Btrfs formatted drive with 4kb cluster size.

... are in sync at first.

If the files you tried to preotect from silent data corruption that don't update the content from time to time, creating a checksum file for those files or parity is what you should do.

Keep in mind checksum file can only verify the integrity of the file, it can't do repair ...

... are in sync at first.

If the files you tried to preotect from silent data corruption that don't update the content from time to time, creating a checksum file for those files or parity is what you should do.

Keep in mind checksum file can only verify the integrity of the file, it can't do repair ...

The best practice to detect bit rot is to create a checksum file for the known good copy of files, and verify the files to detect bit rot, or create parity files for known good copy of files to check and repair corrupted data in files.

Since FreeFileSync main purpose is for files sync, I think it ...

The best practice to detect bit rot is to create a checksum file for the known good copy of files, and verify the files to detect bit rot, or create parity files for known good copy of files to check and repair corrupted data in files.

Since FreeFileSync main purpose is for files sync, I think it is ...

without the feeling that the errors are a covert way of securing another donation
This is not what's happening.

You don't need to donate to reinstall. When you donate, you are given a unique URL/page where you can download the donation edition of the software. Go there, download a fresh copy, and ...

Hello, I have the donated version, with a fault "invalid checksum" as per the screen shot and I am unable to open the program and I do not want to download another as I have already donated twice in the past 12 months, with an other error which cropped up
The questions are
1/ How do I fix this
2/when ...

... Linux.

In a way similar to syncing/mirroring, the process I'm evolving would definitely benefit from using the export file list to "update" the checksum files for only the files that needed mirroring. Currently, "the backup" is ~900 GB, ~135k files and is going to increase significantly soon. These ...

- If the file is new -> generate new checksum files.
- If the file has been changed -> delete the old checksum files and generate new checksum files.
- If the file has been deleted -> delete the old checksum files.

You might find interesting (though it is dealing with Windows, but still), Indexed ...

... compare, then use the export file list as an input to a script, which I'm writing, that will basically run an existing program to generate "checksum" files, so that errors in the "original" files can be detected and corrected, up to some configurable amount.
- If the file is new -> generate new ...

... have figured out ways to get the hashes, but not with an API, and it requires some not-so plug-and-play stuff. They have notated using scripts, programs, and enabling things in the account settings.
MD5 checksum is a field in the JSON metadata for a file though, so maybe it's easier than expected?

I installed 13.7, and when I try to run, I get the attached message mentioning installation files are corrupted and invalid checksum. I reinstalled 13.6 and everything runs as expected. Any suggestions?

Error message reads
"Consistency check failed for "C:\Program Files\FreeFileSync\Resources\Registered.dat
Invalid checksum"

I have been running the donation edition for ages then this came up today.

I don't want uninstall/reinstall in case I lose my list of file matches.

Any suggestions??

Thanks ...

Theoretically, files can have an identical checksum and still differ in content.
That is however very, very unlikely, and, as explained in said threads, not the reason why FFS does not use hashes.

... Drive sync: by time and size and file content (byte-by-byte comparison)

However, I noticed that gdrive api v3 file metadata object exposes `md5Checksum` field.
Would be nice to add this as sync option. Previously for something like that to happen, you had to download file from a cloud (and there ...

... tried again - this time it appeared to work but when I looked at the .log it had apparently failed again because the sync files didn't pass their checksum (yet the backup had worked fine the night before).

I have attached my .ffd as well as the error.log file - could someone please tell me what ...

LeoW

xCSxXenon,

Is there a way to tell free file sync to do a checksum after each file is transferred?

LeoW

... check if they are the same. The -n flag tells rsync to do a dry run and not change anything. The -c flag tells rsync to compare the files using a checksum instead of just comparing the file sizes and modification times.

Here is an example of how to use it:

rsync -vnc /path/to/source/ /path/to ...

... 2023-06-13 14_23_59.331.log

Or even better

SyncSettings 2023-06-13 14.23.59_331.log

or [the best in my opinion]

SyncSettings 2023-06-13 14.23.59 331.log

or eventually

SyncSettings 2023-06-13 14_23_59 331.log

And by the way: what is that last 3-digit number? A checksum of some sort?

... of the changed file.

Only if some service would be running on the remote machine that can provide FFS the momentary hash of the remote file, a checksum based approach could/would potentially be attractive.
But as this is normally not the case, and depends on the remote file server, FFS can not ...

... pasting the same file to a different location in the drive on both sides is still detected by the software upon comparing them again). Or is the checksum of the file tracked by the file every time a comparison is run?

I've tried to read the documentation and search the forums before posting this ...

Delete that "sync.ffs_db" file and try again

This has been fixed for the next release:

FreeFileSync 11.28
------------------
Recover from corrupted database file

That was a regression compared to older releases. FreeFileSync will automatically overwrite a corrupted DB file, if the error is ...

I'll just point out the "very often" bit, which you would think you should not be running into, very often:

I get then very often (not always!!) this error message: cannot be read, the file content is corrupt (invalid checksum)

Delete that "sync.ffs_db" file and try again

Hello FORUM!
I have (for a long time already) a problem
with "FreeFileSync" for Windows 10.
For more see attachment: .jpg file.
Greetings from Germany
Sigmund

... such command will "hit" all files in scope, not just the ones just copied over or updated.

You could also have FFS invoke some self-created script-file via the FFS On Completion command line.
That script-file should then determine which file to determine the md5 checksum of, and consequently do so.

Freefilesync is a very great file sync tool, I use it every day.
And I use checksum file created by md5 command to check file integrity.
when I use freefilesync sync some new file to cold storage disk，then I need to
use md5 command create checksum.
step1. use ffs sync changed file
step2. find ...

... FreeFileSync.

Consistency check failed for "D:\Utilities\PortableApps\FreeFileSyncPortable\App\FreeFileSync\Resources\Registered.dat".

Invalid checksum
---------------------------
OK
---------------------------

so, how can I update my portable ffs?

edit: it seems that I have to activate again ...

The use of checksums [...] would not speed up the FFS comparison.

Correct, but performance with checksums is much worse: While FFS is comparing file content it breaks on the first byte difference found. Using checksums on the other hand would always require reading the full file content.

I ...

I join in asking to add an option in the settings to speed up the comparison using the checksum method (perhaps in the donations package along with the other options for performance?).
Open source projects using this approach are very fast:
https://github.com/arsenetar/dupeguru/
https://github.com ...

The zip file had an invalid checksum apparently. Still I couldn't reproduce the "Installer is damaged" error: the pkg was extracted fine on both macOS 12.3 and 10.15 (perhaps the error could be corrected by the extractor?). Fixed and re-uploaded.

... X) drive but did not create/delete any .jpg thumbnail files.

I think an improvement to the tool that can significantly speed up the processes is to create a checksum for each directory. If that checksum has not changed, then content of directory should be skipped for any update/mirror function.

Maybe the SMB protocol incorporates a checksum, I haven't checked.

Gotcha, that makes more sense, but is a little different than the original. Can't say for sure if that's how it's done or not

My point is that "Compare by Contents" should not be done on files of different size - they are different by definition.

Plerry isn't the dev, Zenju is, so he can't answer that question, I don't think. You say checksum is "just a concept" but then what is the point of your post??

Checksum is just a concept. Dou you compare contents of the files of different size?

The use of checksums is discussed many times (https://freefilesync.org/forum/search.php?keywords=checksum).
FFS does not use checksums. Using checksums also does not make sense for FFS, as FFS only runs in one location (which does not even need to be the left nor right location), and in order to ...

Comparison speed by checksum can improved drastically by calculating checksum only for the same path and file size. File size comparison is already implemented, just modify the algorithm by adding checksum to the same size files.

... Windows_Portable.zip
Size: 19,671 KB, alias 20,142,821 bytes
md5: cedf4dd86e8b63a4ed1f9623c8bd2166
So, size is the same as for therube ,
checksum obviously different, as these are donator specific files.

It seems your zip-file does not have the correct size (at 11,246KB).
Simply re-download ...

I'm not sure what exactly file content check means in "Compare" options, does it mean file integrity and checksum checking?
I'm asking this because I sometimes get corrupt files on my usb when copying with windows. I wonder if this program can do such errors detection either if I use "Synchronize" or ...

... Please reinstall FreeFileSync.
Consistency check failed for "C:\Program Files\FreeFileSync\Install.dat"

File content is corrupted. (invalid checksum)

Any ideas as to how this might be solved. I would greatly appreciate any help. I apologize in advance if this is a repost of a similar problem ...

A list of the checksum of all the files copied / synchronized in the database could allow FFS to recheck the integrity of the pairs of unmodified files whose checksum differs during future synchronizations.

And also to be able to back up databases by location profiles elsewhere than at the root of ...

... file would overwrite a healthy backup.

In short, if between 2 files (source and destination) never modified (seen by date) one of them had a checksum different from the first or last synchronization, it would be useful for FFS to be able to detect it and warn of a possible corruption by ...

... I have discovered FreefileSync and would like to know a few things before i buy it.

First of all:
During the first synchronization between two disks with content comparison (bit by bit), do the databases thus produced on each side contain the checksum of each file for a later comparison ?

Cordially

It obviously differs per platform, but for Windows see e.g. here.

Thanks for your reply, Plerry.

The way I see it, adding validation functionality would only improve the quality of what FFS is doing. Rather than just copying files and make sure they appear updated in two locations, one could argue that the users primary concern and interest is in the contents of ...

... and right location rather than calculating the chechsums.

Obviously, nothing prevents you from using a dedicated data verification tool based on checksums, running at either of the sync locations (if you have control over both ends).
But (at least in my view) it does not make sense to include this ...

... to add a vote for this to be implemented.

It would be a great way to allow for data scrubbing. Every time a file is updated, recalculate the checksum. Schedule periodically verification of checksums. If a mismatch is found, we know the file has been corrupted, and should be given the option to ...

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