Why would you want to do this? Troubleshooting just becomes extremely painful, and chances of hitting an issue when running with a configuration like this for a longer time is significant. I would ALWAYS recommend to upgrade all hosts in a cluster ASAP to the same version. Please, just avoid doing this.
Thanks for your advice, but explain the following scenario
I have a 5.5 environment managed by vCenter 6.5 including VUM 6.5 and I want to upgrade hosts to 6.0u3 based on my hardware requirement but VUM will not upgrade 5.5 VMware Knowledge Base
Hosts will be upgraded separately
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Is it possible?
The key part in the other comments is long term, its ok while you are upgrading, just don't leave mixed hosts for a long period of time. We generally try and do all of our hosts in the same day.
you meaning it can?
Of course, will be upgrade hosts quickly
Yes its the only way unless you move the hosts to a new cluster then migrate vms. Just don't turn on any new features until they are completely upgrade. What we did for our 5.5 to 6.5 migration was create a new cluster and reinstall a host a put the host in the new cluster. This made sure we didn't have any left overs from 5.5, but not everyone has capacity to do this.
Thanks for your recommendations
I will study the situation well
start to upgrade in the same cluster carefully if find any mistakes, will take your scenario
I hope to get other recommendations