long time to sync-write

Hi, New user. Wanted to thank Gadget for great help with previous issue. Worked really well.

Current issue: I have a directory from which I am working, which is about 13gb on my working laptop (apple). Machine is a month old, and folder is about 3 weeks old. I am not working with media. On syncthing, the software reports the folder is 20gb. Why the size difference?

On the second machine (headless ubuntu server) after 3 hours syncthing states it is 56% complete at 5.09gb. This size (projected 9.1gb) is not the same as the laptop syncthing (20gb) nor the laptop file browser - 13gb (finder).

Why are these all different? If I samba map to the ubuntu samba server, the sync folder is in a samba share. They are the same files, I have not copied the wrong (massive) fileset. The samba server is serving up zfs datasets, as shares to different users’ laptops.

Further, why has it taken 3 hours to move 5gb of data, on a lan, fully wired, to the same switch, wifi off? Should I be looking at network monitoring tools? Does zfs (no z intent log or arc-cache) slow things down without a rapid write cache/log? Pool is mirror 2*4tb expensive rust.