Windows VFS: new local file automatically dehydrates without notice

[jnweiger]

seen with opencloud-desktop-main-1960-windows-cl-msvc2022-x86_64.exe

install on windows 11 pro 24H2
connect to server
open personal folder in explorer
click new text file
enter a few lines of text

• the client syncs to the server
• the client shows the (v) checkmark icon, (not a cloud icon)

Check size in windows explorer: Properties

• Size: 13 bytes
• Size on disk: 0 bytes

the file was dehydrated. BAD
but the icon shows the checkmark icon (Available on this device). This is inconsistent with size on disk: 0. BAD

Expected behaviour:
Files manually copied to the local laptop remain on the laptop and do not require internet connection.

[jnweiger]

Small files, with 40 bytes or ca 200 bytes exhibit this behaviour: they say size on disk 0 bytes after the sync to the server finishes:

bigger files with e.g. my bigger.txt with 157.123 bytes behaves correctly, it shows 160.000 bytes on disk, after the sync finishes.

[TheOneRing]

The file is not dehydrated. As you can see on the icon.
To test, stop the client, and open the file.
If it's dehydrated, you get an error.

[jnweiger]

You are correct. That is normal (but scary) windows behavior, that also happens outside of the sync root folder. Files smaller than ca 600 bytes are shown as 0 bytes on disk.

This is called a "resident file" it lives -- inside the MFT data structure, which is not counted as space on disk, although it typically occupies 1kb on the disk.
https://learn.microsoft.com/en-us/answers/questions/4271169/small-files-have-a-disk-space-of-0-bytes?forum=windows-all