UEFI Support for Windows Migrations
UEFI (Unified Extensible Firmware Interface) replaces the basic BIOS firmware originally present in most Windows PCs. Utilizing UEFI offers the user various advantages around security and disk management. VMware introduced support for UEFI with vSphere 5.0. As a result, it is possible you are utilizing UEFI on some of the VMs running in your datacenter.
Cloud providers, however, do not support UEFI, so we have developed a special transformation process that will automatically convert UEFI systems to the MBR format during migration. This process, however, has some limitations that are important:
- This process is only currently supported on Windows systems
- This process supports a maximum of 4 visible partitions on the source system.
- Additional details: GPT layouts typically include four partitions: Recovery, EFI (BCD), Reserved (hidden), and at least one user data partition. During our conversion, the reserved partition will be removed. As a result, migrated systems can support two user partitions on the boot disk (for example, a C and a D drive).
- Supports drives up to 2TB
- Software RAID and Dynamic Disks are not supported.
- Systems will be migrated in write-isolation mode, which means any changes to the data is not synchronized back with the on-prem system.
- You can still perform a rollback to on-premises operation, but it is no longer stateful. As in, the system in the cloud will turn off, and the system on-prem will boot back up, but the data changes made in the cloud will not persist to the on-prem system.
When systems meet the requirements above, the conversion will take place automatically when a user selects a system to migrate to the cloud. If the requirements are not met, you will receive an appropriate error message for diagnosis.
Important Note: as mentioned in step 5, it is important to re-iterate that write back is not supported when migrating machines that are are configured with UEFI at source.