Sync is one way or two way

Does sync copy two way the most recent file in a folder or only one way the different file in a folder?

It's one-way.

Other question with Sync option... What append if the sync destination was unavailable... Exemple the destination was an external HDD but not plug when the sync start. Does it give an error message or simply do nothing?

It will log an error then try again when the drive comes online.

So if i set the sync at 3am everyday (The drive unplug) and i plug it a 10am it will make the sync when i plug the drive at 10am or only the next day at 3am?

If you are using the "current time" attribute to schedule it then, it would happen 3am the next day. Is this what you want it to do or do you want it to behave the other way?

Yep the current time way! If the sync not possible (Missing drive) i want the backup to try again next day... I just don't want to have message that tell the drive was missing or something like that! So all will be good! Thanks!

Well, it might do a message if it's missing at 3am but not at 10am.

Tried syncing… Ended up with my Trash full of "XYZ backup", *moved* from my *target* directory… Makes no sense!! o_O

No message of error if the destination drive is missing! (Good for me)

I have the same issue as levifig... If i check on my source and my destination the files was there but a copy in the trash of some too...

That should be a copy of files that were deleted or changed in case you need to restore them for whatever reason. Is the destination not in sync with the source? Not sure what the issue is here.