ESXi host slow download speeds, VM guests are fine, why?

[zdawg]

So, we have a plain on ESXi 6.5 host, and were in the process of trying to download some ISOs directly from ESXi, to put in the datastore for VM creation.

That said, we noticed right off the bat, that the download speeds were INCREDIBLY slow, as compared to a Linux server in the same VLAN, behind the same switch and firewall, same data center, etc etc.

This ESXi host was just installed with the basic/default config, so the Management Network and VM Network share the same default vSwitch, with two physical NICs set to active.

As a test, I went ahead and created a plain Linux VM, and voila the download speeds almost perfectly matched the speeds we were getting from the separate physical Linux server.

So my question is, why does the ESXi host itself have so much latency when downloading, but it's guest VMs do not?  This is more for my own knowledge at this point, as I don't think it matters that much as we can just download whatever we need to one of the guests and scp it to the ESXi host.

[mprazeres183]

Hi zdawg,

That is indeed strange. This should not be the common way, if you did not activate Firewall on the ESXi Host or you didn't change the Management vmkernel to only use like 100MB or something other, this should be 1:1 the same as on the VM Network section.

Could you try this: On this article they test the vmkernel network performance.

kb.vmware.com/s/article/2052119

Then also this here: This here gives you the possibility to change vmkernel settings if missconfigured.

kb.vmware.com/s/article/1004089

Just try it out and let me know if it was some setting issue.

Best regards,
Marco

[Sinorama]

@zdawg

You do not specify how the ISOs are downloaded. I find better speeds using scp compared to the slow downloads in datastore browser.