The Vector client-server architecture allows multiple users access to databases through connections to one or more DBMS Server processes. The DBMS Server (iidbms) is a multi-threaded daemon process that performs asynchronous disk input and output. The number of users connected to a server is limited by hardware or the operating system.

Since it is unlikely that the default DBMS server configuration suits all users' requirements, the DBMS Server is usually configured to improve performance in a configuration. For a selected DBMS server definition, its buffer caches can be configured as well as other parameters and derived parameters.