How do I pin point the bottleneck for slow file transfer speed?

I'm trying to locate the bottleneck for why transfers on my OMV server cap around 50 MB/s. Drives are all connected via SATA, OMV server is connected via gigabit, the computer I transfer to/from is connected via gigabit, all my cables are cat5e or cat6, switches are all gigabit.

I was using the same computer/hard drives/ethernet cables/switches when I was running Win10 as my server OS a few weeks ago and was getting 110-112 MB/s transfers on/off the server. But since I switched from Win10 to OMV, have never been able to hit those numbers.

Since then, I originally thought it was because my drives were formatted NTFS so reformatted them all to EXT4, (moving TBs of data around from one HD to another, which was a pain), but even after completely getting rid of NTFS, speed cap still seems to be the same.

Hard drive to Hard drive transfer (both on OMV server, both drives connected via SATA, both EXT4 format)

OMV server to Computer transfer (over ethernet)

Any thoughts or idea on what I can try next?

Zitat von Agricola

This article is a bit dated but may help understand transfer speeds on your LAN.

Thanks, so its my harddrive/sata connection itself that's the bottleneck?

Doesn't make sense why I was getting full gigabit transfer speeds when Win10 was my server OS. Does Windows artificially boost the numbers?