Probably is possible to do but just seems a bit risky, better option is to confirm health / replication both before and after each one is done.
--please don't forget to upvote
and Accept as answer
if the reply is helpful--
This browser is no longer supported.
Upgrade to Microsoft Edge to take advantage of the latest features, security updates, and technical support.
i have 5 2012r2 DCs. 2 in one site, 3 in the other site.
I am introducing 3 new 2019 DCs in one site, and 3 DCs in the other site.
I don't want to do them one at a time if i don't have to.
Not demoting anything this night just promoting. the 5 2012 r2 DCs will stay online.
Is there any problem with Promoting 1 at each site at the same time, or just promoting all of them at the same time?
Probably is possible to do but just seems a bit risky, better option is to confirm health / replication both before and after each one is done.
--please don't forget to upvote
and Accept as answer
if the reply is helpful--
As @Anonymous said, theorically it should not cause any issue. I have already tried this in a lab environment and it's working fine. But i would recommend to promote one DC at the time.
It sounds like what you really might benefit from is scripted DC promotions. This will automate the repeated tasks and reduce the chance of human error--while also giving you the possibility (if you really want it) of doing near-simultaneous promotions. Still, the best advice is to test replication health between each one.
Much of the work can be scripted with PowerShell or by using an unattend answer file.
Documentation for the unattend file can be found here, and it is supported at least up through Windows Server 2019.
PowerShell is the ideal way to do it now. Here is an example of what that could look like:
Install-WindowsFeature AD-Domain-Services -IncludeManagementTools
Import-Module ADDSDeployment
Install-ADDSDomainController `
-NoGlobalCatalog:$false `
-CreateDnsDelegation:$false `
-CriticalReplicationOnly:$false `
-DatabasePath “C:\Windows\NTDS” `
-DomainName “example.com” `
-InstallDns:$true `
-LogPath “C:\Windows\NTDS” `
-NoRebootOnCompletion:$false `
-SiteName “Default-First-Site-Name” `
-SysvolPath “C:\Windows\SYSVOL” `
-Force:$true
FMI, review the documentation for Install-ADDSDomainController.