I built new hosts which were added to an existing cluster. After taking them out of maintenance mode, I cannot vMotion VMs to the new hosts. I followed this KB article and this blog post. Nothing worked. I was on the verge of resetting one host.
vim-cmd vimsvc/task_list showed several tasks like below, it didn’t seem right.
I thought of checking jumbo frame which turned out to the culprit. This cluster uses VSS. I changed the MTU to 9000 for VMkernel NAS interface but forgot to do so at the vSwitch level which is 1500 by default. After changing the MTU at the vSwitch level, it worked immediately.