Real time disk scheduling plays important role in time critical applications. Conventional database are mainly characterized by their strict data consistency requirements. Database systems for real-time applications must satisfy timing constraints associated with transactions. The numbers of algorithms are proposed to schedule real time transactions in order to produce the overall performance. This paper presents the overview of existing approaches for scheduling the real-time transactions. Earliest Deadline First (EDF) is a basic algorithm which meets the real time constraints, but it gives poor disk throughput. Adaptive Earliest Deadline (AED) improves the performance which uses feedback control mechanism to attain HIT ratio 1.0. Hierarchical Earliest Deadline (HED) maximizes the sum of the values of those transactions that commit by their deadline, and minimizing the number of missed deadlines becomes a secondary concern. The study investigated performance of EDF, AED algorithms, from which experimental result shows that AED gives better performance under overloaded condition.