A server system comprising storage devices, processing devices and a storage fabric all operating according to a storage fabric protocol. The storage fabric comprises a plurality of individual switches having a modular design from which an overall switch is built, and the individual switches have individual respective configuration settings which determine which processing devices are allocated to use which of the storage devices. The system comprises an API enabling a software control function to configure the overall switch. The API is operable to receive from the control function an overall mapping of the storage devices to the processing devices instead of requiring the individual configuration settings of each of the individual switches to be specified by the control function, the API being configured to convert the overall mapping into the individual configuration settings of the individual switches to produce the overall mapping.