3 identical synchronised maps

[LetMeBackup]

I have 3 identical folders:

(1) Google Drive
(2) Microsoft OneDrive
(3) Double Drive

My intention now is to use FreeFileSync and RealTimeSync to get all these 3 folders synchronised with each other.

So if something is modified in (1), (2) or (3), I want it to be automatically modified in the other two folders as well. So which rules exactly do I need in FreeFileSync?

Left Right
Google Drive Microsoft OneDrive
Google Drive Double Drive
Microsoft OneDrive Double Drive

ChatGPT gives me this, but I'm doubting... Anybody who can help me?

[dennisb]

I think two sync jobs would do it.

First sync any two locations, then use a second job to sync the third location with one of the first two.

If you use a RealTimeSync then you may have to increase the "minimum idle time" to insure the first sync is completed before starting the second sync.

[LetMeBackup]

Thanks for your answer @dennisb

So you can't synchronise these 3 maps at the same time?

[dennisb]

Actually you can but I'm not sure about a RealTimeSync for three locations. Try it.

On the main screen, click on the green plus sign to add another folder pair.

[LetMeBackup]

After a lot of hours I think I managed to get the right configuration.

However, I'm wondering if "sync (1).ffs_lock" and "sync (2).ffs_lock" do need to be always visible in one of my three folders? Or is it possible to hide these two FFS_LOCK-files somehow?

[Plerry]

You can prevent the ffs_lock files being created by setting the LockDirectoriesDuringSync flag to False. But be aware of the risk.

With the LockDirectoriesDuringSync flag set to True, the ffs_lock file is created at the start of an FFS sync, and removed upon its completion.
However, some cloud services have a habit of still retaining a copy of one or more previous versions of "deleted" files for you.
There is little FFS can do about that.

[LetMeBackup]

You can prevent the ffs_lock files being created by setting the LockDirectoriesDuringSync flag to False. But be aware of the risk.

With the LockDirectoriesDuringSync flag set to True, the ffs_lock file is created at the start of an FFS sync, and removed upon its completion.
However, some cloud services have a habit of still retaining a copy of one or more previous versions of "deleted" files for you.
There is little FFS can do about that.

Thanks for your answer. But can you please explain the exact "risk" of putting the "LockDirectoriesDuringSync flag" to false? Because I don't exacty understand the risk of it.

[Plerry]

From the Manual page

The lock files are only recognized by FreeFileSync and make sure that at most, a single synchronization is running against a certain folder at a time while other instances are queued to wait. This ensures that only consistent sets of files are subject to synchronization. The primary use case are network synchronization scenarios where multiple users run FreeFileSync concurrently against a shared network folder.

[LetMeBackup]

From the Manual page

The lock files are only recognized by FreeFileSync and make sure that at most, a single synchronization is running against a certain folder at a time while other instances are queued to wait. This ensures that only consistent sets of files are subject to synchronization. The primary use case are network synchronization scenarios where multiple users run FreeFileSync concurrently against a shared network folder.

I had read this beforehand, but the reasoning behind it was not entirely clear to me.

[xCSxXenon]

I had read this beforehand, but the reasoning behind it was not entirely clear to me.

FFS session #1 runs a compare and wants to update C:\VeryImportantDocument.txt
FFS session #2 runs a compare and also wants to update C:\VeryImportantDocument.txt
Session #1 runs the sync and updates the file.
Session #2 runs the sync and updates the file, overwriting the version session #1 just wrote

Google "Race condition" for more in-depth details
This may not be of concern to you and your setup, but this is up to you to decide

[LetMeBackup]

Thanks for your explanation, I understand it now