Syncovery Support Forum

I back up all my photos to S3. I wasn't able to run my profile for over a month. When I did yesterday it wanted to backup all the files again. As far as I can tell S3 changed the date on all of them. I believe the contents remained the same otherwise. I've attached before and after log files. Any idea what happened?

Hello,
S3 can't actually preserve the original modification timestamps, so it's normal that you see different modification dates.

But I now discovered a bug in Syncovery 11.5.0, which causes it to believe the files' content hashes don't match.

I will release a fixed version ASAP (this weekend).

The problem has been fixed in version 11.5.1.

In addition, you should remove a setting in your profile that causes unnecessary delays and doesn't work with S3:

Under "Verification", remove the checkmark "Right Side". This is only for the Syncovery Remote Service, which isn't on S3.

Concerning the timestamps, as I mentioned, S3 cannot preserve your original modification dates.

Syncovery offers to encode the timestamp into the filename, but then the names look a bit strange if you look directly at the S3 storage. It's fine for most use cases, but in your profile, you didn't choose the Filename Encoding.

So, the files will usually have newer timestamps on S3 than the local originals. Therefore, even if Exact Mirror is chosen, Syncovery would ignore the feature to "overwrite newer files with older ones".

I noticed you chose a combination of settings to work around this limitation and do a full MD5 hash comparison of the files every time the job runs. The settings you needed for this purpose are:
- Ignore Timestamp Altogether (when size is identical, on the Comparison tab sheet)
- Binary Comparison Of Existing Files (this will automatically use MD5 checksums with S3, except for huge files)

So if this doesn't take too long or use too much CPU, you can keep these settings. They do a thorough comparison of local files with S3 every time, without using extra bandwidth.

Something you could turn off is "Verify Sync Statistics After Completion". That's always an additional comparison step which might not be necessary.

tobias, thank you for another prompt and accurate fix and a useful explanation of S3 date handling. The profile ran successfully with "Nothing to do"