File Transfer capped at less to 1Gbit on a 10Gbit Network

[Giannino Zontini]

Hi Guys, need some help figure out what the **** is not working in our infrastructure.

For a fast brief:

1 VSphere on a Vcenter 7.0.3

9 Hosts Dell PowerEdge R740xd (2 Clusters)

1 Cluster (5 Hosts) for Servers

1 Cluster (4 Hosts) for Horizon

1 VSwitch per Hosts is connected to 2 Dell Switches with Unity 480 for iScsi e vMotion

1 VSwitch per Hosts is connected to 2 Dell s4048t-on  with OS9 in VLT (Core Switches)

From the Core, there is a PO to a Barracuda Firewall F800

Problem:

i never, ever, in any point of that network, reach a 10Gbit speed during a file transfer.

The usual speed is 600-700 Mbits write 2-3 Gbits read

And if i try to move file from a VLAN to another, speed getting cutted more (300 Mbits write)

During tests with Iperf, i reached 10 Gbits speed setting up the -w option at 2048k (TCP Window size) 

From Host to Host the speed is 10Gbits

I deployed 2 new VMs for tests, Windows 2022 , each on the same VLAN , on the same Host and on the same Datastore, and the max speed that i reached during a copy file (i use LAN Speed Test) is 850 Mbits write and 4 Gbits read

I m banging my head on a wall since 2 month , moving Unity away from the core, updated all the Hosts bios,FW,Driver, reconfigured Switches , vSwitches and VLANs , but i cannot pass the 1Gbit speed. Checked Cables and all is Cat6 or 7 

The first step that i'm trying to achieve is a good speed from VMs on the same hosts (so, internal to VSphere)

Need some advice or holy water :D 

[Michael Gardner]

Hello,
Your infrastructure setup seems correct, but you're experiencing slow file transfer speeds (~600-700 Mbps write, ~2-3 Gbps read) between VMs on the same host. You've tried various troubleshooting steps, including updating hosts, switches, and cables, but the issue persists. To isolate the problem, try:

1. Checking VM network settings and ensuring they're set to use the correct vSwitch.
2. Verifying that the storage datastore is not a bottleneck.
3. Testing with a different VMkernel port or vSwitch to rule out configuration issues.
4. Using esxtop or other monitoring tools to identify potential resource contention. Official Website

If none of these steps resolve the issue, consider seeking guidance from VMware support or a qualified infrastructure expert.

[Muhammad Ali]

Yeah checking VM network settings can help. Because they're set to use the correct vSwitch.

[Gary Morrisette]

Adding on to what others have suggested.  I would give HCIBench a shot and see if this catches anything.

https://github.com/vmware-labs/hci-benchmark-appliance/tree/main