Change?? Syncthing reserving full file size as a .tmp file first

Hi, I am a new Syncthing user and it is perfect for my needs - syncing a Seedbox to a Linux desktop folder.

I might be going crazy but I am sure that, when I started using Syncthing a few weeks ago, while files were syncing, I could look at the file in the directory and see its size increasing as it was pulled down. The filename was as it should be (e.g. file.mkv).

Now, when I am syncing, I see the file appear in the directory as file.tmp, at its full size immediately - it then changes to file.mkv when it is finished syncing.

Has this always been the case and I am going mad? Or have I changed an option somehwere that has caused this change to my system?

Cheers. Darren

This is normal, at least for a file which has been modified elsewhere, and the changes are now about to be made on the local file. The reason is that the update must be atomic, to guarantee that the local file is in one of these two states and nothing in between:

  1. Same as before.
  2. Same as remote.

I am not sure if this applies to a file which was not on your device before.

The file is always created with the final size, but it’s “sparse”. If you check disk usage with du you’ll see it increase as downloads progress. It may be a full “size reservation” if the file system doesn’t support sparse files, like maybe FAT.

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