The TPC-C benchmark is a new benchmark approved by the TPC council intended for comparing database platforms running a medium complexity transaction processing workload. Some key aspects in which this new benchmark differs from the TPC-A benchmark are in having several transaction types, some of which are more complex than that in TPC-A, and in having data access skew. In this paper we present results from a modelling study of the TPC-C benchmark for both single node and distributed database management systems. We simulate the TPC-C workload to determine expected buffer miss rates assuming an LRU buffer management policy. These miss rates are then used as inputs to a throughput model. From these models we show the following: (i) We quantify the data access skew as specified in the benchmark and show what fraction of the accesses go to what fraction of the data. (ii) We quantify the resulting buffer hit ratios for each relation as a function of buffer size. (iii) We show that close to l...

In this paper we present practical experiences gathered from the employment of two popular Java-based mobile-agent platforms, IBM's Aglets and Mitsubishi's Concordia. We present some basic distributed computing models and describe their adaptation to the mobile-agent paradigm. Upon these models we develop a set of frameworks for distributed database access over the World-Wide Web, using IBM's Aglets and Mitsubishi's Concordia platforms. We compare the two platforms both quantitatively and qualitatively. For the quantitative comparison, we propose, employ, and validate an approach to evaluate and analyze mobile-agent framework performance. For the qualitative assessment, we present our observations about the programmability and robustness of, and mobility provided by, the two platforms.

An understanding of application I/O access patterns is useful in several situations. First, gaining insight into what applications are doing with their data at a semantic level helps in designing efficient storage systems. Second, it helps create benchmarks that mimic realistic application behavior closely. Third, it enables autonomic systems as the information obtained can be used to adapt the system in a closed loop. All these use cases require the ability to extract the application-level semantics of I/O operations. Methods such as modifying application code to associate I/O operations with semantic tags are intrusive. It is well known that network file system traces are an important source of information that can be obtained non-intrusively and analyzed

To Candi, for her love, support, and many years of patience. ACKNOWLEDGEMENTS Those who praise “thinking outside the box ” have never had to deal with a gradu-ate student who chose a thesis topic outside every one of his department’s “boxes.” Many people have gone above and beyond the call of duty to provide me the re-sources and advice needed to finish this dissertation. First, I want to thank Kimberly Keeton, Ralph Becker-Szendy, John Wilkes, Allistar Vietch, and everybody else in the Storage Systems Department at HP Labs for granting me the privilege to join them for a summer, and for continuing to support my research after I had returned to Georgia Tech. Second, I want to thank Ann Chervenak, Ken Mackenzie, Kishore Ramachandran, and all the other faculty at Georgia Tech for providing the moral and financial support that allowed me to pursue my storage systems research. Third, I thank Chad Huneycutt, Josh Fryman, and all the other students at Georgia Tech who spent time editing my papers and critiquing my talks. Nobody was under any

Whenever distributed transaction processing in MANETs or other unreliable networks has to guarantee atomicity and isolation, a major challenge is how long-term blocking of resources can be avoided in case the mobile device looses connection to other participants of the transaction. We present a new technique for treating blocked data of transaction participants that wait for a coordinator’s commit decision. Our technique, Bi-State-Termination (BST), gives participants that have moved during transaction execution the possibility to continue transaction processing before they know the coordinator’s decision on transaction commit. The key idea of our technique is to consider both possible outcomes (commit and abort) of unknown transaction decisions. Within this paper, we describe a fast implementation of the fundamental relational database operations for a DBMS supporting the BST transaction synchronization protocol that avoids longterm transaction blocking.