Share same folder from different OSes

General
1

I decided to ask before I do something stupid and wreck my files. Here’s the deal.
I have 2 computers. Computer A has a single OS, Debian linux. It is sharing a couple of folders.
Computer B has had a single OS until now, Windows 11. And has been sharing the same folders with computer A.
But now I want to start dual-booting computer B, between W11 and Manjaro. This means that I want to share the same folders in both OSes of computer B.
Let’s remember that W11 has a single NTFS partition and that Manjaro will have two Ext4 partitions (/ and /home).
Let’s forget about computer A and focus on computer B. What do I need to do in order to make this work?
It’s true that Manjaro can mount NTFS, but W11…well, it could mount Ext4, but I don’t want to commit suicide trying to make that work.
So I thought about creating an extra FAT32 or exFAT partition and put those couple of shared folders on the extra partition. Both OSes would be able to access the same data.
But…would that be the supported way of doing it? Or should I have duplicate folders, one on the NTFS and one on the Ext4 for sharing data through syncthing? Thanks in advance.
Cheers\

2

You can share the files from both OSes, but you also need to share the database and config (more or less; config could be different for the two as long as it’s equivalent for the folders). In practice it means something like a “portable” Syncthing setup living entirely on your shared FAT disk.

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3

You got me a bit lost with the portable syncthing thing.
So, I’d have to OSes, with syncthing installed on both of them.
Now what exactly do I need to do? You said I should share the config, but in Windows I will have other shared folders that I won’t be sharing when I’m on Linux.
TIA Cheers

4

Please check https://forum.syncthing.net/t/dual-boot-ntfs/16683/9 on how to make Syncthing portable.

However, in your case, it seems that you should just store those folders in a location that can be accessed from both OSs and then add them to Syncthing in each of them separately. When doing so, make sure to enable “Ignore Permissions” in the folder advanced settings as well.

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5

Sweet. Then it seems to be super straightforward, just as anyone would do without asking here first. Right?

Hmmm, I wonder what kind of impact that will have. Should I worry?

6

Umm… To me this sounds like a bad piece of advice. And to the best of my understanding it goes against this:

7

In general, it’s recommended to enable “Ignore Permissions” when sharing files between different operating systems (which is Windows and Linux in your case).

Yes, my suggestion is a different approach, but you cannot share the config and database if you only want to re-use some of the folders (which is what the user here does).

8

If you can’t share the database you can’t share the data, or you will cause data loss.

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9

Ha! This is what I was afraid of. This means I should use separate folders for both (W11 & Lnx) syncthing instances, right? TIA Cheers

10

In what kind of situation would it cause data loss?

I’ve tested the following scenario:

  1. There are three devices - Synching 1, Syncthing 2, and Syncthing 3.
  2. There is one storage device accessible from both Syncthing 1 and Syncthing 2.
  3. I shared a folder located on the shared storage between Syncthing 1 and Syncthing 3.
  4. I shared the same folder between Syncthing 2 and Syncthing 3.
  5. At the same time, only Syncthing 1 or Syncthing 2 is running. Syncthing 3 is always running.
  6. I made changes inside the folder when Syncthing 1 was running. It pushed those changes to Syncthing 3. Then, I shut Syncthing 1 down.
  7. I turned Syncthing 2 on. It correctly detected that the folder state has changed on the disk and that it matched the state on Syncthing 3, so no further synchronisation was necessary.
  8. In this scenario, the folder on the disk was re-used between Syncthing 1 and 2, but their configs and databases were all separate.
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11

Possibly not straight up data loss, but definitely conflicts.

Assuming devices R (remote) and OS1/OS2 (dual booting host, OS #1 or OS #2). Databases are not shared.

  1. R and OS1 are connected, some file changes, gets synced.
  2. OS1 shuts down.
  3. A change happens to the file on R.
  4. OS2 boots. Content on disk doesn’t match database (because of the change in 1.) Change conflicts with the one sent by R, conflict is created.
  5. You need to resolve the sync conflict to figure out which was the latest state of the file.
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12

Yeah, so I’m not sure if I’m doing something different, but I’ve tried to force conflicts the way you described, however I’m not getting any. It just syncs with no issues here.

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