Download VMDK file from Datastore Browser or Copy VMDK file via WinSCP very slow

[Huu An Nguyen]

Hello All member from vmware community teams, 

I have an ESXi vSphere host running version 7.0U3 with 4 uplinks to a Core switch at 10Gbps with an MTU of 1500. We have configured vmk0 for both Management and vMotion. However, when attempting to download a VMDK file from one of the VMs, the download speed is very slow. We also tested using WinSCP over SSH and the OVF CLI export, but the issue persisted with similarly slow speeds (0,2-0,5 Gbps). Vmkernel have configure with static IP, using MTU 1500 and using NIC Teaming with 2 uplink (vmnic0, vmnic1).

I tried creating two VMs with different VLANs and copied an ISO file between them. The transfer speed was excellent, around 6-8Gbps. Do you have any suggestions on how to resolve this issue?

Appreciate with your help, 

Thanks and Regards!

[CSpreha]

As far as I know, this has never been changed, but the kernel network speeds have always been limited, this has existed for generations of ESXi.  We have hosts with 1, 10, 25GbE and upload speeds are always slower than expected.  Also realize most people's PCs at an organization are at 1GbE to the desks, or even less if on a laptop with wifi, and even less if you are telecommuting over your home internet.  Try it from a desktop or a VM that's local to the datacenter and see if your speeds improve, but it will never be at the line-speed of your kernel NICs, just part of ESXi life.

[Huu An Nguyen]

Hello, 

The jump host server is used to connect to vCenter and the vmk are on the same VLAN and both use 10Gbps. I don't think there is any issue related to the vmkernel limitation because it wasn't mentioned in the VMware and Broadcom documentation later on.

[Vlad_AUS01]

Could you try to download file, by connecting to ESXi UI, not vCenter?

[bseklecki_ge]

Yea, downloaded it via VCSA/VCenter means that the file has to move laterally through the Datacenter network, first from the Hypervisor to the VMSA/vCenter VM (which may or may not be hosted on the same ESXi/vSphere host), then to the 3rd party management statino.

  It is a really super inefficient problem; For example, it happens when we're publishing 15-25GB OVAs into the VCSA/vCenter CONTENT LIBRARY ( which are often stored on a NFS NAS datastore, it adds a 4th hop).  So 25GB becomes 100GB in the network, and what should take 3 minutes takes one hour, even at 25gb or 40gb 

[Huu An Nguyen]

Hello,

The problem is jump host and ESXI using the same core switch :)

I think it problem related vinh setting, I will try testing and validate config to see if anything mis configure.

Thank!

[Huu An Nguyen]

Hello,

Yeah I tried that to with download via browser, winscp or OVF tool Cli but the result show the same.

[bseklecki_ge]

Use an NFS mounted NAS/SAN for bulk high volume maintenance operations.  You can get a SYNOLOGY NAS with a 10GB interface for $125.  There is no undocumented/obfuscated QoS Policy within the VMWare ESXi/vSphere management domain kernel applied to NFS or iSCSI traffic.