Two Syncthing-folders for one folder?

I’d like to use Syncthing to backup folders to an offsite-machine. Problem is that I already syncthing those folders between devices, but I’d like to keep the backup easy on CPU and RAM by increasing scan time. While creating two Syncthing-folders for each folder (1 with scan time of 60 sec shared with A and B, 1 with 60 min shared with A, B and OFFSITE) I got a warning. What’s the risk here? Doesn’t Syncthing realize it’s actually the same folder and always propagate the newest states? Is there another way to do this?

The scan time only affects the device you set it on. By adding a folder twice you are doing more scans, not fewer. The remote device doesn’t know or care if you have a one second or one hour scan interval.

Yeah, sure. But if changes occur, they’re only sent to the one device every 60 sec and only every 60 min to both, no?

Correct. So in that respect, the other device will get less to do because it will get fewer updates.

The warning is there because, perhaps opposite of what you expect, Syncthing does not realize that the two folders are actually the same thing on disk. So if a change comes in from another device, it’ll be updated on disk. Then the other folder looking at the same files will scan and see the change, interpret it as a local change, and propagate it away to other devices. It works, when set up properly, but it’s an odd and unusual config and not very well tested.

You’ll probably end up with conflicts.

So better use Syncthing on the offsite device just like on the others or look for another solution? Increasing scan time on the offsite device alone won’t reduce it’s CPU and RAM usage much, will it?

Wouldn’t increasing the scan interval just cause more CPU and RAM usage when actually syncing? With normal scan interval, the receiving side will often have little do do, while with increased scan interval, it will have sometimes much more to do. The average will be more or less the same, but higher scan interval will have more risk of blocking the receiver for other tasks.

If you use one st folder for A<->B and on for A->offsite or B->offsite while setting it to master on A or B, there should be no probklem (no conflicts). But you can only use one of A or B to sync to offsite.

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