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vSphere 5 Licensing Change Ramifications

07/13/2011

Until now, vSphere licenses have focused on populated physical processor sockets.  To maximize the bang-for-the-buck, we sought few processors with as many cores as our vSphere license would permit and load ’em up with RAM.  Picture a 6-host cluster where each host has two 10-core processors and 192GB RAM running vSphere Enterprise Plus.

In this case, we buy twelve Enterprise Plus licenses, entitling us to 576GB vRAM.  This is a N+1 HA cluster, so we can consume up to 5 hosts-worth of pRAM, or 960GB.  This leaves us having to purchase an additional EIGHT licenses of Enterprise Plus to cover processors we don’t actually own.  Sure, we could configure the cluster as N+2, reducing my effective capacity from 83.3% to 66% and still have to buy four more licenses just to use all the pRAM in the cluster.

Compounding the frustration is that we’ve been encouraged to make use of great features like transparent page sharing which make memory over-subscription easy and efficient.  Now, if I apply a 1.5:1 memory over-subscription rate to my cluster above, I may have to come up with EIGHTEEN Enterprise Plus licenses for processors we don’t actually own.

I am aware that the vRAM entitlement is pooled by license type across the entire vCenter-managed VMs, so if you have a couple of 2-host clusters, you might be able to apply some of that entitlement to the bigger clusters…

With this license change, I think VMware is driving people to use smaller, less efficient clusters.  Customers are effectively penalized for having more than (Number of Hosts-1) * vRAM entitlement per CPU in their hosts.

This is just my humble opinion and does not necessarily reflect the opinion of my employer or partners or anyone else for that matter

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