CPU and Memory Reservations for NSX Edges (not changed when appliance sizes are changed)
Starting from NSX version 6.3.2 NSX makes CPU and RAM reservations based on the appliance sizes. You can turn this off by setting this to “No Reservations”.
But if you have turned this on the system makes a 100% reservation by default. So if you deploy an X-Large Edge then the CPU reservation is 6000 Mhz and the RAM reservation is 4096 MB.
Now when you decide to downgrade the Edge Appliance size (for whatever reason) from X-Large to Quad Large. This reservation is NOT changed by default. (At least not in NSX-v 6.3.4). It could be that this will be changed in future versions... So what is reserved is still 6000 Mhz for CPU and the RAM reservation is 4096 MB but to reflect the new size (quad large) this should actually be 4000 Mhz and the RAM reservation is 2048 MB.
You can change this by manually changing the reservation parameters:
Or you can change it to “No Reservations” click OK and change it back to “Custom” and it will contain the required / correct reservations for that correct appliance size.
My reason to change this was that the reservations made (by NSX) where too high and vSphere HA admission control started complaining that it could not respect the 50% threshold because no resources where available.