Your Active Directory (AD) sites and subnets should represent the actual data center locations, offices, and network topology as closely as possible. In your Cloud Volumes Service project, place domain controllers in the same region as your volumes and define an AD site for that region. When Cloud Volumes Service is connected to your domain, the service uses DNS-based discovery to find the right domain controllers to communicate with. By specifying a site in the AD settings of Cloud Volumes Service, you tell it to search only domain controllers for that site.
For the CVS service type, you must either use AD sites or enable Global Access to Active Directory for storage pools. If you enable Global Access to Active Directory, using AD sites is optional but recommended.
For the CVS-Performance service type, using AD sites is optional but recommended.
Without site specification, DNS-based discovery might identify domain controllers outside of the region. Trying to create a volume can fail due to connection timeouts.
Deploy at least one domain controller in the Cloud Volumes Service region and connect the domain controllers to your existing AD.
Create an AD site for your Google Cloud region and place the appropriate domain controllers into that site.
Use the AD site when setting up AD connections.
To verify that your AD site contains only reachable domain controllers, see How can I identify Active Directory domain controllers used by the CVS and CVS-Performance service types?
For more information, see Active Directory: Design Considerations and Best Practices.