The H-Sphere system database is used to store system data. In normal H-Sphere configuration, it runs on PostgreSQL server, but it may be installed on a separate Windows-based MSSQL server.
Usually, the system database is located on the same server with the Control Panel.
The system database is not used for hosting. PostgreSQL hosting server could not be installed on the same box with the system database.
The H-Sphere database is executed under the pgsql or postgres user.