Files synced via Syncthing show correct size but zero disk usage (du/df) on target

Support
1

Environment:

  • OS: Ubuntu (both source and target)
  • Syncthing version: ( v1.30.0)
  • Setup: Source → Target replication using Syncthing
  • Filesystem: ext4

Problem Description:

I am observing an issue with .dat files generated using dd on the source system.

  • Files are created on source using dd

  • Syncthing successfully transfers the files to the target

  • Syncthing UI shows correct file size (e.g., 1 GB)

  • stat on target shows proper size but the blocks are 0.

  • du -sh on target shows 0 size

  • df -h does not reflect any increase in disk usage

Example:

# On target
stat testfile_10.dat

Size: 1073741824
Blocks: 0

du -sh testfile_10.dat
# Output: 0

Additional Observations:

  • When the same file is transferred using rsync, disk usage is correctly reflected
  • Issue occurs only with Syncthing-transferred files
2

Are the contents not what you’d expect?

3

My concern is the blocks are not getting copied for these files.

4

My guess is they don’t need to be, because the files are all zeroes or content you already have on disk with copy-on-write enabled.

1 Like
5

You are correct, there is no content inside the file.

2 Likes