Three ways sync

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Posts: 8
Joined: 27 Apr 2018

AlexGiov

Hello,

is it safe to perform a three-way synchronization as follows, in the same projec?

a <> b
b <> c
c <> a

In attached the screenshot of freefilesync setting
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2018-04-27 10_35_16-_FreeFileSync 9.9 – Comparazione delle Cartelle e Sincronizzazione.png
2018-04-27 10_35_16-_FreeFileSync 9.9 – Comparazione delle Cartelle e Sincronizzazione.png (29.88 KiB) Viewed 1736 times
Posts: 8
Joined: 27 Apr 2018

AlexGiov

Hello again everybody,

I try to better explain what I mean.
I have three folder and I would like to keep these folder synchronized running a single FreeFileSync project or batch file.
Let call these folder: A, B and C. Is it ok if I set FreeFileSync to do the following syncroniztion between folder:

A sync with B
B sync wth C
C sync with A

I get in my mind the following question: are these three syncronization thread executed in parallel or serilized one after the other?
Is these type of three way syncronization a correct use of the program or I can get some problems?

Thanks for help,
Alex
Posts: 292
Joined: 13 Apr 2017

Gianni1962

I think you are looking for trouble.

It is not enough to have two "two way" sync?

A - B
A - C
Posts: 8
Joined: 27 Apr 2018

AlexGiov

Absolutely not.Iin the case that you mentioned (simple two way sync) B folder will miss the modification done in C folder. In the case that you mentioned you get three way sync if you run twice the same project.
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Zenju

are these three syncronization thread executed in parallel or serilized one after the other? AlexGiov, 28 Apr 2018, 10:50
One of the core concepts of FreeFileSync is to split the synchronization into two steps:
1. comparison (with a GUI preview)
2. execution (also called "synchronization") doing exactly what is shown on preview

This two-step approach will obviously be a problem when there are dependencies between folder pairs, because the result of the sync of the first folder pair will have an impact on the comparison of the first. But the comparison is not being repeated after the first folder pair has finished synchronizing.

So to answer your first question: FreeFileSync has no problem running 2-way, 3-way, ... N-way synchronizations as long as they are not part of the same synchronization run. IOW you will have to sync the dependent folder pairs one after another.
Posts: 8
Joined: 27 Apr 2018

AlexGiov

Yep! Extremely clear, thank a lot for help. I'll do a batch like this:
Run (two step) comparison and execution of A < > B
Run (two step) comparison and execution of B < > C
Run (two step) comparison and execution of A < > C

Congrats for your great work on FreeFileSync!