Hi,
I have a set up of QNAP TS431X2 (RAID5 4x4gb IronWolf) connected to CSS326-24G-2S+RM (SwOS 2.7) via SFP+ cable (10Gb) and then I do have external router for internet connection on port 1 on CSS and teamed 2xLAN on my workstation (Win 7 pro) plugged in to port 3 and 4 on CSS.

Teamed adapter on workstation displays 2Gbps connection as it should.
In SwOS LAG recognise Trunk of port 3&4 and connected partner.

The issue is that I can not reach transfer speed grater then 1Gbps. My Teamed Lan adapters shows that only 50% of network utilization.

I am looking forward for any suggestions how to solve my problem and achieve full 2Gbps transfers on SMB.

Best Regards,
Krzysztof

That's normal: Ports aggregation works by sending the traffic of "one session" over 1 port and the traffic of "another session" over another port. Also, packets from the same MAC source to the same MAC destination (sometime IP address are used or even IP/port but that's pretty uncommon) will always go through the same port (with LACP). So if your traffic is between a limited number of computers, you will never get the added capacity of all the team ports.

If you transfer a single file between 1 computer and another, you will never get more than the speed of a single port of the team. That's why you get 1Gbps and not 2Gbps.

One way to go around that is to use a dumb switch that doesn't handle LACP: On some such switch, when several ports are connected to the same network, it will just use round-robin to send packets through each ports, one after another. LACP doesn't use this kind of method and send 1 session fully through a single port so that packets always arrive in the correct order.

Maybe try this:
In SwOS, leave the LAG mode of the port on "passive".
On the QNAP, set the trunking to either Balance-rr, Balance-tlb or Balance-alb. (ie dont use IEEE 802.3ad)

I don't know if SwOS will handle Balance-rr. Balance-tlb and Balance-alb will work without any support from the switch (it may not even list the port as being part of the same trunk)