2 research outputs found
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IP storage : a performance and security study, LDRD 04-1021.
Effective, high-performance, networked file systems and storage is needed to solve I/O bottlenecks between large compute platforms. Frequently, parallel techniques such as PFTP, are employed to overcome the adverse effect of TCP's congestion avoidance algorithm in order to achieve reasonable aggregate throughput. These techniques can suffer from end-system bottlenecks due to the protocol processing overhead and memory copies involved in moving large amounts of data during I/O. Moreover, transferring data using PFTP requires manual operation, lacking the transparency to allow for interactive visualization and computational steering of large-scale simulations from distributed locations. This paper evaluates the emerging Internet SCSI (iSCSI) protocol [2] as the file/data transport in order that remote clients can transparently access data through a distributed global file system available to local clients. We started our work characterizing the performance behavior of iSCSI in Local Area Networks (LANs). We then proceeded to study the effect of propagation delay on throughput using remote iSCSI storage and explored optimization techniques to mitigate the adverse effects of long delay in high-bandwidth Wide Area Networks (WANs). Lastly, we evaluated iSCSI in a Storage Area Network (SAN) for a Global Parallel Filesystem. We conducted our benchmark based on typical usage model of large-scale scientific applications at Sandia. We demonstrated the benefit of high-performance parallel VO to scientific applications at the IEEE 2004 Supercomputing Conference, using experiences and knowledge gained from this study
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Robust message routing for mobile (wireless) ad hoc networks.
This report describes the results of research targeting improvements in the robustness of message transport in wireless ad hoc networks. The first section of the report provides an analysis of throughput and latency in the wireless medium access control (MAC) layer and relates the analysis to the commonly used 802.11 protocol. The second section describes enhancements made to several existing models of wireless MAC and ad hoc routing protocols; the models were used in support of the work described in the following section. The third section of the report presents a lightweight transport layer protocol that is superior to TCP for use in wireless networks. In addition, it introduces techniques that improve the performance of any ad hoc source routing protocol. The fourth section presents a novel, highly scalable ad hoc routing protocol that is based on geographic principles but requires no localization hardware