My organization has a vSphere environment with 6 clusters and a variety of VMs (Windows 2K3+, Linux, Solaris etc)
I have been tasked (asked) to answer a seemingly simple question: is there enough capacity to upgrade the Windows 2003/2008 virtual machines to Server 2012 R2?
I'm no architect, but I've been given a list with the VMs that they want to upgrade and a report with oversized VMs (from vRealize Operations Manager). Looking at said report there are many oversized VMs, and some are extremely oversized (eg. 8-core CPU when 1 CPU might be enough). So just from this report I think there is no problem to go ahead with the upgrades, because we can easily reclaim tons of resources.
However, because this is a big decision, I can't just say "yeah I think its doable". I need to provide a serious analysis.
But how do I go about it? Initially I was thinking about doing some calculations from a "GHz" perspective, as in how many extra GHz do I need and how many I have "free" (or am able to free through resource reclamation with vROPS).
But then, CPU usage might not change that much since the applications remain the same (right?). Maybe I should look at how many cores each VM uses? However it seems to me that Win Server 2012 R2 has some pretty low minimum requirements, 1x 64bit CPU and 512MB RAM whereas all the VMs have much more than that..
And what about RAM? Should I assume maybe +512MB when upgrading from Windows 2008 machines and +1GB for Windows 2003 ? Would that make sense?
What do you guys think? Any suggestions would be appreciated, including tools, scripts etc.
