Nested ESXi lab, mac learning enabled, slow vMotion

Hello Reddit,

I’ve built a 3 nested ESXi 6.7 hosts lab out of an HP z420 with 128 GB of RAM and a E5-2640.
I’m not particularly interested in tuning my lab for high performance, my objective is to maintain my sysadmin skills and learn new ones.

However, after vmotioning my VCSA from one host to another, I noticed that the vMotion speed was not really close to what I would expect. Speed is not terrible but I’m just wondering how come I’m not achieving more than 3.5 Gb/s ?

As far as I understand, the data that is being moved around in a nested vMotion job resides in the RAM of my physical host so it there should be not bottleneck at that level.

My nested ESXi host VMs are configured with the standard VMXNET 3 adapter. Within ESXi, vmnics are configured in 10 Gbit/s, Full Duplex. The vMotion VMkernel is attached to a dvswitch where mac learning is enabled. And the underlying network with the ESXi VMs is also also attached to a dvswitch with mac learning enabled.

Why am I not getting close to the max speed of 10 Gbit/s when I vMotion?

View Reddit by lucien62View Source

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  1. In the wild I don’t ever see my vmotions hit anywhere near 10gbps but you’ll need to do some tuning on the hypervisor and virtual networking to help such as disable large receive offload, disable Nagle’s Algorithm (TCP_NODELAY) and enable jumbo frames. These are the types of things you have to do with iSCSI too to maximize performance.

    What’s your parent host’s CPU usage? is it spiking or maxed out?

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