minimal percentage of domain controllers online

Solution 1:

Active Directory Forest Recovery - Perform initial recovery

https://docs.microsoft.com/en-us/windows-server/identity/ad-ds/manage/ad-forest-recovery-perform-initial-recovery

If the restored domain controller hosts an operations master role, you may need to add the following registry entry to avoid AD DS being unavailable until it has completed replication of a writeable directory partition:

Key: HKLM\System\CurrentControlSet\Services\NTDS\Parameters  
Value: Repl Perform Initial Synchronizations  

Create the entry with the data type REG_DWORD and a value of 0. After the forest is recovered completely, you can reset the value of this entry to 1, which requires a domain controller that restarts and holds operations master roles to have successful AD DS inbound and outbound replication with its known replica partners before it advertises itself as domain controller and starts providing services to clients.