In ISPmanager Business, the unified name and UID/GID space is used for all servers.
User account is created in the operating system of the less loaded web server. You can configure policies to let the system determine which server is considered less loaded. This same server will contain real files of its users.
There are a few scenarios of how you can use servers for web hosting:
each server performs all roles; in this case, a user will always have its data on this server,
there is a dedicated mail server processing mail of all users,
there is a dedicated database server storing databases of all users.
Users are edited and deleted on all servers that contain their data.