Abstract: A real-time write function is provided for a multimedia server system by reserving appropriate disk bandwidth for real-time needs at system configuration time. Blocks of a real-time record are avoided irrespective of the duration of the record which otherwise would occur while awaiting availability of system resources. A preseleted number of disk blocks are pre-allocated so as to keep ahead of the writing real-time application by a designated amount. A system administrative interface is provided to specify before and during the write the duration that the system is to keep ahead of the writing real-time application. Given the duration and the rate at which the application intends to write or record, the number of pre-allocated disk addresses is computed. The addresses are kept in a pre-allocation table maintained on a "per-open instance" basis. A real-time write application also reserves a determined number of prefetch buffers.