Figuring out transfer bottlenet or issues

Just set up TrueNas core system and when i’m transferring files to the NAS the connection maxes out at ~85mb/s. After reading some other posts i feel like it should be faster.

The GUI dashboard is reporting “1000baseT” this was from a dell precision 3640 so not sure what exact NIC was, running 4 12tb Seagate Exos in RAID Z1 with default set. Boot drive is an NVMe and 8 GB RAM

and my other computer has Realtek 8111h gigabit controller.

When i test via iperf it shows 700 Mbits/sec. which makes me think if i divided that by 8 it gets to the 85mb/s.
But when reading from the NAS to my windows machine it’s showing 110 mb/s
And when i had both systems as windows before it would reach ~200 mb/s no problem.
The whole difference between mebibytes and bits and megabits making things more complicated. But basically, how do i know if this is the max speed or what’s the bottleneck?

Can you please post your complete hardware setup, including the exact type of HDs.

How did you setup your pool?

Realtek chipsets are often the cause for sub-optimal performance. The same is true for SMR Drives on ZFS.

Updated with more details let me know what else you believe is pertinent;

1000Base T is ~ 1Gbit/s ~ 125MByte/s
With overhead 110Mbyte/s is about what to expect.

Ahh I see, i’m hitting ~85 MByte/s on transfers to the NAS so can I assume that’s mainly overhead when going to NTFS to ZFS, or perhaps something else going on?