CRAID: Online RAID upgrades using dynamic hot data reorganization

Current algorithms used to upgrade RAID arrays typically require large amounts of data to be migrated, even those that move only the minimum amount of data required to keep a balanced data load. This paper presents CRAID, a self-optimizing RAID array that performs an online block reorganization of frequently used, long-term accessed data in order to reduce this migration even further. To achieve this objective, CRAID tracks frequently used, long-term data blocks and copies them to a dedicated partition spread across all the disks in the array. When new disks are added, CRAID only needs to extend this process to the new devices to redistribute this partition, thus greatly reducing the overhead of the upgrade process. In addition, the reorganized access patterns within this partition improve the array’s performance, amortizing the copy overhead and allowing CRAID to offer a performance competitive with traditional RAIDs. We describe CRAID’s motivation and design and we evaluate it by replaying seven real-world workloads including a file server, a web server and a user share. Our experiments show that CRAID can successfully detect hot data variations and begin using new disks as soon as they are added to the array. Also, the usage of a dedicated partition improves the sequentiality of relevant data access, which amortizes the cost of reorganizations. Finally, we prove that a full-HDD CRAID array with a small distributed partition (<1.28% per disk) can compete in performance with an ideally restriped RAID-5 and a hybrid RAID-5 with a small SSD cache.Peer ReviewedPostprint (published version

LIGO Physics Environmental Monitoring at the 40-meter Prototype

When Einstein formulated General Relativity, he made numerous predictions including the existence of gravitational waves. Until now, though, they have been impossible to detect. LIGO, the Laser Interferometer Gravitational-Wave Observatory, has been built to overcome this. Major difficulties arise as a result of the fact that gravitational waves are inherently weak; LIGO is expected to detect stretching on the order of 10-18 meters. With the need for such precise measurements, a very large number of unwanted effects have to be minimized. Thus, physical environmental effects must be monitored with care and analyzed. Among the tools needed are a weather monitor, accelerometers and seismometers, and vacuum monitors. Each of these devices must be connected to the network and queried by the database, and the data coming from them must be analyzed. In order to accomplish all this, we must setup the hardware; write code to query each device and format the data; create GUIs to display the data; and design data analysis programs. Such systems have been designed and built for the two LIGO observatory sites. In this project I implement a Physical Environmental Monitoring system for the Caltech 40-meter Interferometer Prototype Laboratory, and analyze the data obtained

Network performance monitors

Over the last 10 years both industry and academia have conducted extensive research and development in the areas of local area network management and performance. This thesis investigates some different ways of measuring the performance of local area networks and studies hardware and software systems designed to watch over network performance and events. These systems are termed network performance monitors. As part of the thesis, a network performance monitor has been implemented to monitor TOOLSNET, an Ethernet based local area network, supervised by the Engineering Tools Technology group at Compugraphic Corporation. This network performance monitor is called TOOLSNET ANALYSIS PACKAGE, or TAP for short. TAP runs Monday through Friday, from 8 a.m. to 5 p.m. to monitor TOOLSNET performance during working hours. A summary of the measurements from one of these 5 day sessions is reported in this paper. This summary includes the following tables: one showing a system by system contribution to TOOLSNET traffic for the session; another that shows the amount the network was utilized each day of the session; another that shows the total number of random errors experienced by TOOLSNET during the session; another that shows asymptotic throughput utilization, perceived utilization, relative load, and average response time for each day of the session; another that shows source-to-destination traffic for each day of the session

Reverse Engineering: WiMAX and IEEE 802.16e

Wireless communications is part of everyday life. As it is incorporated into new products and services, it brings additional security risks and requirements. A thorough understanding of wireless protocols is necessary for network administrators and manufacturers. Though most wireless protocols have strict standards, many parts of the hardware implementation may deviate from the standard and be proprietary. In these situations reverse engineering must be conducted to fully understand the strengths and vulnerabilities of the communication medium. New 4G broadband wireless access protocols, including IEEE 802.16e and WiMAX, offer higher data rates and wider coverage than earlier 3G technologies. Many security vulnerabilities, including various Denial of Service (DoS) attacks, have been discovered in 3G protocols and the original IEEE 802.16 standard. Many of these vulnerabilities and new security flaws exist in the revised standard IEEE 802.16e. Most of the vulnerabilities already discovered allow for DoS attacks to be carried out on WiMAX networks. This study examines and analyzes a new DoS attack on IEEE 802.16e standard. We investigate how system parameters for the WiMAX Bandwidth Contention Resolution (BCR) process affect network vulnerability to DoS attacks. As this investigation developed and transitioned into analyzing hardware implementations, reverse engineering was needed to locate and modify the BCR system parameters. Controlling the BCR system parameters in hardware is not a normal task. The protocol allows only the BS to set the system parameters. The BS gives one setting of the BCR system parameters to all WiMAX clients on the network and everyone is suppose to follow these settings. Our study looks at what happens if a set of users, attackers, do not follow the BS\u27s settings and set their BCR system parameters independently. We hypothesize and analyze different techniques to do this in hardware with the goal being to replicate previous software simulations that looked at this behavior. This document details our approaches to reverse engineer IEEE 802.16e and WiMAX. Additionally, we look at network security analysis and how to design experiments to reduce time and cost. Factorial experiment design and ANOVA analysis is the solution. In using these approaches, one can test multiple factors in parallel, producing robust, repeatable and statistically significant results. By treating all other parameters as noise when testing first order effects, second and third order effects can be analyzed with less significance. The details of this type of experimental design is given along with NS-2 simulations and hardware experiments that analyze the BCR system parameters. This purpose of this paper is to serve as guide for reverse engineering network protocols and conducting network experiments. As wireless communication and network security become ubiquitous, the methods and techniques detailed in this study become increasingly important. This document can serve as a guide to reduce time and effort when reverse engineering other communication protocols and conducting network experiments

Belle II Technical Design Report

The Belle detector at the KEKB electron-positron collider has collected almost 1 billion Y(4S) events in its decade of operation. Super-KEKB, an upgrade of KEKB is under construction, to increase the luminosity by two orders of magnitude during a three-year shutdown, with an ultimate goal of 8E35 /cm^2 /s luminosity. To exploit the increased luminosity, an upgrade of the Belle detector has been proposed. A new international collaboration Belle-II, is being formed. The Technical Design Report presents physics motivation, basic methods of the accelerator upgrade, as well as key improvements of the detector.Comment: Edited by: Z. Dole\v{z}al and S. Un

Scalable Storage for Digital Libraries

I propose a storage system optimised for digital libraries. Its key features are its heterogeneous scalability; its integration and exploitation of rich semantic metadata associated with digital objects; its use of a name space; and its aggressive performance optimisation in the digital library domain

The MAGCLOUD wireless sensor network

Initially, the aim of this project consisted in manufacturing some nodes for a wireless sensor network by hand. If this document concludes that they can be properly produced in the EETAC lab, the cost of a future large deployment using raw components would be much lower than in the case of acquiring the genuine factory assembled hardware. Also, the future students involved in the process could learn many useful advanced techniques along the way. The project ended sowing a future WSN concept, so powerful that even could end competing on the market. We designed an almost unlimited scalable platform in terms of range, number of nodes, connectivity and measuring capabilities that is 100% free, open and environment sustainable. We called this unique wireless magnitude acquisition cloud: THE MAGCLOUD. The whole system cannot be fully finished within the time and budget restrictions of a single PFC but slicing it into diverse future upgrades is a completely realistic approach. In this document, sticking to the original idea, we explain how to produce the functional hardware and software skeleton but also guide the reader on the future upgrades required to complete the MAGCLOUD system. During the realization of the project we found countless problems that luckily end up solved. Those are carefully treated so can be avoided in the future

Towards Seamless Mobility: An IEEE 802.21 Practical Approach

In the recent years, mobile devices such as cell phones, notebook or ultra mobile computers and videogame consoles are experiencing an impressive evolution in terms of hardware and software possibilities. Elements such a wideband Internet connection allows a broad range of possibilities for creative developers. Many of these possibilities can include applications requiring continuity of service when the user moves form a coverage area to another. Nowadays, mobile devices are equipped with one or more radio interfaces such as GSM, UMTS, WiMax or Wi‐ Fi. Many of these technologies are ready to allow transparent roaming within their own coverage areas, but they are not ready to handle a service transfer between different technologies. In order to find a solution to this issue, the IEEE has developed a standard known as Media Independent Handover (MIH) Services with the aim of easing seamless mobility between these technologies. The present work has been centered in developing a system capable to enable a service of mobility under the terms specified in the stated standard. The development of a platform aiming to provide service continuity is mandatory, being a cross‐layer solution based in elements from link and network layers supplying a transparent roaming mechanism from user’s point of view. Two applications have been implemented in C/C++ language under a Linux environment. One application is designed to work within a mobile device, and the other one in the network access point. The mobile device basically consists in a notebook equipped with two Wi‐Fi interfaces, which is not a common feature in commercial devices, allowing seamless communication transfers aided by the application. Network access points are computers equipped with a Wi‐Fi interface and configured to provide Internet wireless access and services of mobility. In order to test the operation, a test‐bed has been implemented. It consists on a pair of access points connected through a network and placed within partially overlapped coverage areas, and a mobile device, all of them properly set. The mobile detects the networks that are compatible and gets attached to the one that provides better conditions for the demanded service. When the service degrades up to certain level, the mobile transfers the communication to the other access point, which offers better service conditions. Finally, in order to check if the changes have been done properly, the duration of the required actions has been measured, as well as the data that can have been lost or buffered meanwhile. The result is a MIH‐alike system working in a proper way. The discovery and selection of a destination network is correct and is done before the old connection gets too degraded, providing seamless mobility. The measured latencies and packet losses are affordable in terms of MIH protocol, but require future work improvements in terms of network protocols that have not been considered under the scope of this work

X-Databases - The Integration of XML into Enterprise Database Management Systems

An examination of how the eXtensible Markup Language (XML) and database management systems (DBMS) fit together, and current approaches to providing database technologies that support XML. Analysis of how XML is being deployed in four classes of XML Database (X-Database) applications provides a basis for understanding the direction of X-Database technology and associated standards. In a simple implementation, an XML Document Type Definition (DTD) is mapped to relational structures, and XML data are stored in a DBMS (Oracle8i). Sample queries are presented to retrieve XML from the database. A middleware tool (XSQL Java Servlet) is used to transform query results into records on a Web page. The results demonstrate that relational databases require data to be rigidly mapped to relational structures. The paper concludes by exploring future challenges to integrating XML and DTDs with X-Databases, which establishes the need for a more "native" integration approach