A Generic Cluster-Based Solution for Data Intensive Services

A cluster-based architecture with a proxy and a few back-end servers is a popular solution to face the ever increasing demand for data-intensive services. Stateof-the-art Cluster-based servers employ a proxy that is responsible for distributing incoming requests to the back-end server in a manner that is transparent to clients. The back-end servers send the response to the proxy, which then forwards it to the client. The overhead of processing each packet at the proxy affects the response time adversely. Moreover, since the entire traffic from all the servers has to pass through the proxy, it often becomes the bottleneck. In this paper, we propose an architecture for cluster servers which provides a generic solution for the above mentioned problems. It is achieved by sending the response from the back-end server directly to the client, bypassing the proxy altogether. Thus, we eliminate the overhead of traversing the network stack at proxy which involves costly kernel-user context switches and data copies between the kernel and user space buffers. The technique used to achieve this is called Connection Handoff. The paper also argues the aptness of SCTP (Stream Control Transmission Protocol) as the transport layer protocol for our clusters. SCTP is similar to TCP but has additional features like multistreaming, multihoming, immunity to DoS attacks, prevention of Head of Line Blocking etc. These features make it a better choice as the transport layer protocol for our project. Using the technique of SCTP handoff along with features like Load balancers and Content-Aware-Dispatcher, we aim at improving user response times and overall throughput rates for a variety of data-intensive services, improving the scalability and robustness of the cluster servers at the same time.