Frederico Buchholz Maciel

Dynamic Gateways: A Novel Approach to Improve Networking Performance and Availability on Parallel Servers

Parallel servers realize scalability and availability by effectively using multiple hardware resources (i.e., nodes and disks). Scalability is improved by distributing processes and data onto multiple resources; and availability is maintained by substituting a failed resource with a spare one. Dynamic Gateways extends these features to networking, by balancing the traffic among multiple connections to the network in order to improve scalability, and detours traffic around failed resources to maintain availability. This is made transparent to the clients and to applications in the server by using proxy and gratuitous ARP to control the network traffic. A performance evaluation shows that Dynamic Gateways improves the scalability (allowing the maximum networking performance to increase with increasing number of connections) and the performance (improving throughput and reducing access latency).

A scalable, cost-effective, and flexible disk system using high-performance embedded-processors

As a scalable, cost-effective, and flexible solution for data-intensive systems, we are exploring active-network-storage (ANS), which is an array of ANS disk drives. The ANS drive improves flexibility by using a modular software design; that is, users can specify functions of the ANS drive by loading/unloading the corresponding modules on it. To keep the ANS drive cost-effective, users are allowed to choose whether native code modules or platform-independent Java-bytecode modules are executed on the drive. We forecast that a current high-performance embedded-processor is powerful enough to enable this modular design to be implemented and to provide a scalable, cost-effective, and flexible ANS system. We have confirmed our forecast by conducting an experiment with an ANS drive prototype with a 200 MHz embedded-processor running database sequential scanning and NFS, which are typical off-loaded functions with different characteristics. To evaluate scalability and cost-effectiveness of the ANS system, we estimated the throughput from measurements on our ANS prototype, and we compared it with the throughput that was measured on a 450 MHz Pentium II Xeon server. Our estimation indicates that the scan throughput of the ANS system increases up to 71 MB/s while that of the server saturates at 25 MB/s because of its CPU bottleneck. The NFS read/write throughputs of two ANS drives surpassed the server maximum throughputs.