I sync large directory (50Gb) by local network between 2 nodes (Mac OS X Sierra and Mac OS X Hight Sierra) and noticed different sizes on each node (50.5 Gb vs 49.92 Gb).
Then I find differents between some files (jpg, png) on each node (for ex.: 631 Кb on main node vs 510 Kb on synced node). Hash is identical of both.
Syncthing Version: v0.14.45, macOS (64 bit)
Syncthing nodes: Mac OS X Sierra, Mac OS X Hight Sierra (latest update at the date above)
Surely the hash is not the same if the contents are different.
If I copy these files (bigger and smoller from 2 nodes) into the Windows envirement sizes are the same, but copying manualy between Mac OS keep different sizes.
I have such an impression that Mac OS keep some cache or additional info of files and show bigger size… Sync by Syncthing ignore it.
Please, help to understand…
Probably no, because copying one of them to the one of nodes, I can see 2 identical files near each other with different sizes (through get info).
They’re not identical if their sizes are different.
How do you compute the hashes? Maybe use a non-mac tool to compute them, just to satisfy the non-trusting folks (like me). Actually Syncthing did and says they are the same, so my bet is on mac-shenanigans.
Another theory, that I am not sure about: Couldn’t two “identical” files but one sparse have the same hash but not the same size? Don’t know whether png can be sparse at all.
Isn’t it the way Kb or Kbi are differently counted between linux and windows ?
But it’s a copy of the same file on the same OS.
I suspect it’s some sparse file stuff.
NODE1 (MacOS 10.12.6):
A.png (631Kb) = MD5(5dc2beed60598512aee6a060c1229130)
NODE2 (MacOS 10.13.3) synced:
A.png (510Kb) = MD5(5dc2beed60598512aee6a060c1229130)
The same hash result with http://onlinemd5.com/
On Windows 7 (virtual machine) A.png on NODE1 = 510Kb
After image optimaze (like Tinypng) both files go to the same size.
What about hidden MacOS metadata like __MACOSX ?
Maybe, could be a hidden preview in a resource fork or something.
You could try
xattr <filename> on each file.
You can sometimes find something hidden there that the OS counts towards the file size.
Thank you, it’s true.
MacOS: Folder Admin$ xattr A.png
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