Hi,
If your AD doesn't have any 3rd party schema extensions, then there should be little issues with the schema update itself. However, there are a few pre-requisites steps I would take before completing the schema update:
- Confirm the health of your AD, run repadmin dcdiag and fix any issues before starting
- Test the schema update - if you have a virtual environment spin up a snapshot of a DC holding the Schema role in an isolated network, complete the schema update to confirm it will work without any errors
- Complete a full verified backup of your DCs
- Check AD replication
- Complete the schema update on the DC holding the Schema Master FSMO role
- Check AD replication
Depending on the configuration of DNS and time services in your network, you might want to move the IP address of the PDC & primary DNS servers is the new DCs, this could help reduce the number of downstream systems that need to be reconfigured.
Gary.