Statistical admission control in video servers with constant data length retrieval of variable bit rate streams

We consider the admission control problem in video servers that retrieve video data from disk storage. Admission control decides whether or not a new client can be accepted without affecting the quality of service promised to the already admitted clients. Assuming variable bit rate (VBR) video streams, we consider an admission control policy that provides statistical service guarantees and evaluate its performance in terms of the number of clients admitted. The admission control criterion needs to take into account how the data are retrieved from disk We assume GCDL retrieval [1] that reads the video data from the disk as several constant size data blocks. We are the first to introduce and analyze statistical admission control with GCDL retrieval and to establish the correspondence between GCDL retrieval and ON-OFF sources in ATM networks.We show that statistical admission control for GCDL, compared to a deterministic admission control, admits up to twice as many clients with one overload event every few hours of video server operation.