vCPU Hot Plug - Do you enable it on Windows Server 2012 R2 templates?

[stephenrbarry]

I'm considering implementing vCPU hot plug on my Windows Server 2012 R2 template.  In the past, there were some issues with vCPU hot plug but it seems to be much improved with 2012 R2 and ESXi 5.5.

I'm curious to hear others' experiences, whether they are positive or negative.  Do you use vCPU hot plug on your VM's?  What are the pro's/cons, and common "gotchas"?  I'm aware that certain applications like SQL have some restrictions because they do their own CPU scheduling, and that vNUMA gets disabled, but I'd be curious to hear about other nuances like that.

This is only for Server 2012 R2, not previous version of Windows.

[rcporto]

There is an overhead and the impact may be considered, check this blog post: http://www.yellow-bricks.com/2012/01/16/enabling-hot-add-by-default-cc-gabvirtualworld/

And I'm unaware about any new enhancements on ESXi 5.5 and Windows Server 2012 R2 about hot add feature 😞

[stephenrbarry]

Yeah I've seen that blog, you'll actually find a post by me at the bottom asking this same question.

I guess "enhancement" was the wrong word; I just meant that with Server 2012 vCPU hot plug and RAM hot add are fully supported and it seems to be more stable than in the past.

The overhead KB is interesting, but it references Windows Server 2003 and the /3GB switch so it's very outdated.  I'm looking for more updated information relating to Windows Server 2012 +.  Does it suffer from the same issue?  Based on the description of the KB, it doesn't seem like it does.