What are the advantages to having UEFI set on a VM?
UEFI firmware is a successor to legacy BIOS firmware that supports larger hard drives, faster boot time and provides more security features.
Creation and starting VMs with UEFI firmware provide the following advantages.
Avoid legacy option ROM address constraints
Include robust reliability and fault management
Use UEFI drivers
Are there disadvantages of enabling UEFI on a VM?
Not per se however not all guest operating systems are compatible. For AHV Please always check compatibility matrix AHV Administration Guide: Compatibility Matrix for UEFI Supported VMs.
Also keep in mind that cluster conversion and cross-cluster migrations might be affected by enabled UEFI:
Ensure that you do not have VMs with UEFI boot firmware enabled when converting from ESXi to AHV. See Prism Web Console Guide v.5.16: In-Place Hypervisor Conversion.
VMs with UEFI boot configuration do not boot after migration when migrating between ESXi clusters with Move. See Move User Guide: Limitations for Migration from ESXi to ESXi.
How to migrate VMs from ESXi to AHV?
Nutanix now supports migration of UEFI VMs from ESXi to AHV starting from AOS 5.11 and Move 3.3.x. Refer the document to find more details regarding the procedure Move User Guide. See KB-5622 How to migrate UEFI VMs from ESXi to AHV.
AOS 5.10 and older have limited support of UEFI VM. Starting from AOS 5.11, Nutanix fully supports VMs natively created on AHV and migration of UEFI VMs through Move 3.3.0 and above.
How to enable/disable UEFI on a VM?
You can create or update VMs with UEFI firmware by using the acli commands, Prism web console, or Prism Central UI. For more information about creating a VM through Prism web console or Prism Central UI, see the Creating VM (AHV) section in the Prism Web Console Guide or Prism Central Guide respectively. For more information about creating a VM through aCLI, see Creating VMs by Using aCLI.