5. vCloud Resource Design : 5.8 vApp : 5.8.1 General Design Considerations
   
5.8.1 General Design Considerations
The following are general design considerations for vApps:
*Use a default of one vCPU unless requirements call for more (such as a multithreaded application).
*Always install the latest version of VMware Tools™.
*Deploy virtual machines using default shares, reservations, and limits settings unless a clear requirement exists for doing otherwise.
*For virtual network adaptors, use VMXNET3 if supported.
*Secure virtual machines as you would physical machines.
*Virtual hardware versions 7, 8, and 9 are supported, depending on the vSphere host version backing the hosts in the provider virtual datacenter. Virtual hardware version 9 is supported in vSphere 5.1.
*Verify that the virtual machine virtual hardware version matches the highest required version within the provider virtual datacenter. The highest version chosen is the highest available with the provider virtual datacenter.
*Use standard virtual machine naming conventions.

5.8.1.1. Virtual Hardware Version 9
vCloud Director 5.1 exposes the highest version of virtual hardware available in the provider virtual datacenter. Users can choose the virtual hardware version desired up to the latest version supported by the provider virtual datacenter for their organization virtual datacenter. vSphere 5.1 supports the use of virtual hardware version 9.
Virtual hardware version 9 provides capabilities to vCloud vApps such as Windows 8 XP mode, 64-bit nested virtualization, and CPU-intensive workloads.
*Windows 8 XP mode – XP mode allows a virtualized XP instance to run for compatibility with older applications that do not natively run on Windows 8. Users who need to run XP mode in Windows 8 must choose an organization virtual datacenter that is backed by a provider that allows version 9 virtual hardware. After specifying virtual hardware version 9, the user must also enable the Nested HV feature.
*64-bit nested virtualization – Hyper-V and virtualized ESXi nested virtualization can be helpful for non-production use cases such as training and demonstration environments. Virtualized Hyper-V or virtualized ESXi running nested 64-bit virtual machines requires virtual hardware version 9 with the Nested HV feature enabled.
*CPU-intensive workloads – Users who need to run an extremely CPU-intensive workload in a virtual machine that requires 32 to 64 vCPUs must use virtual hardware version 9.