According to the data affinity, DAFA re-organizes data to maximize the parallelism of the affinitive data, and also subjective to the overall load balance. This enables DAFA to realize the maximum number of map tasks with data-locality. Besides the system performance, power consumption is another important concern of current computer systems. In the U.S. alone, the energy used by servers which could be saved comes to 3.17 million tons of carbon dioxide, or 580,678 cars {Kar09}. However, the goals of high performance and low energy consumption are at odds with each other. An ideal power management strategy should be able to dynamically respond to the change (either linear or nonlinear, or non-model) of workloads and system configuration without violating the performance requirement. We propose a novel power management scheme called MAR (modeless, adaptive, rule-based) in multiprocessor systems to minimize the CPU power consumption under performance constraints. By using richer feedback factors, e.g. the I/O wait, MAR is able to accurately describe the relationships among core frequencies, performance and power consumption. We adopt a modeless control model to reduce the complexity of system modeling. MAR is designed for CMP (Chip Multi Processor) systems by employing multi-input/multi-output (MIMO) theory and per-core level DVFS (Dynamic Voltage and Frequency Scaling).; TRAID deduplicates this overlap by only logging one compact version (XOR results) of recovery references for the updating data. It minimizes the amount of log content as well as the log flushing overhead, thereby boosts the overall transaction processing performance. At the same time, TRAID guarantees comparable RAID reliability, the same recovery correctness and ACID semantics of traditional transactional processing systems. On the other hand, the emerging myriad data intensive applications place a demand for high-performance computing resources with massive storage. Academia and industry pioneers have been developing big data parallel computing frameworks and large-scale distributed file systems (DFS) widely used to facilitate the high-performance runs of data-intensive applications, such as bio-informatics {Sch09}, astronomy {RSG10}, and high-energy physics {LGC06}. Our recent work {SMW10} reported that data distribution in DFS can significantly affect the efficiency of data processing and hence the overall application performance. This is especially true for those with sophisticated access patterns. For example, Yahoo's Hadoop {refg} clusters employs a random data placement strategy for load balance and simplicity {reff}. This allows the MapReduce {DG08} programs to access all the data (without or not distinguishing interest locality) at full parallelism. Our work focuses on Hadoop systems. We observed that the data distribution is one of the most important factors that affect the parallel programming performance. However, the default Hadoop adopts random data distribution strategy, which does not consider the data semantics, specifically, data affinity. We propose a Data-Affinity-Aware (DAFA) data placement scheme to address the above problem. DAFA builds a history data access graph to exploit the data affinity.; The evolution of computer science and engineering is always motivated by the requirements for better performance, power efficiency, security, user interface (UI), etc {CM02}. The first two factors are potential tradeoffs: better performance usually requires better hardware, e.g., the CPUs with larger number of transistors, the disks with higher rotation speed; however, the increasing number of transistors on the single die or chip reveals super-linear growth in CPU power consumption {FAA08a}, and the change in disk rotation speed has a quadratic effect on disk power consumption {GSK03}. We propose three new systematic approaches as shown in Figure 1.1, Transactional RAID, data-affinity-aware data placement DAFA and Modeless power management, to tackle the performance problem in Database systems, large scale clusters or cloud platforms, and the power management problem in Chip Multi Processors, respectively. The first design, Transactional RAID (TRAID), is motivated by the fact that in recent years, more storage system applications have employed transaction processing techniques Figure 1.1 Research Work Overview] to ensure data integrity and consistency. In transaction processing systems(TPS), log is a kind of redundancy to ensure transaction ACID (atomicity, consistency, isolation, durability) properties and data recoverability. Furthermore, high reliable storage systems, such as redundant array of inexpensive disks (RAID), are widely used as the underlying storage system for Databases to guarantee system reliability and availability with high I/O performance. However, the Databases and storage systems tend to implement their independent fault tolerant mechanisms {GR93, Tho05} from their own perspectives and thereby leading to potential high overhead. We observe the overlapped redundancies between the TPS and RAID systems, and propose a novel reliable storage architecture called Transactional RAID (TRAID).

No description available.

No description available.

År 2002 fattade den svenska riksdagen beslutet att sluta bygga skyddsrum. Sverige har per capita näst flest antal skyddsrum i världen. Ett stort antal skyddsrum i Sverige, kombinerat med beslutet att inte bygga dem längre, har lämnat Sverige vid en vägkorsning. Hur mycket bör Sverige bry sig om sina skyddsrum? För utländska fiender kan skyddsrum verka som ännu ett hinder för att invadera, på grund av de svenska civila möjligheterna till att vara säkra från bomber och ett krigs påverkan. Även om krigföring har förändrats under åren och nya strategier har utvecklats, kommer en säker plats för civila att stärka den försvarande sidan. För att detta försvar ska fungera måste skyddsrummen vara konstruerade på tillgängliga platser för civilbefolkningen, erhålla det material som skyddsrummen är i behov av, kunna drivas av en civil samt vara i gott skick. Det var under kalla kriget som Sverige byggde de flesta av sina skyddsrum. Med många decennier och olika lagar för konstruktion som passerat, har många av skyddsrummen problem i nuläget. Problem såsom att material saknas, luftfilter har blivit för gamla, rummen har renoverats till något annat, eller helt enkelt att skyddet inte kan garantera den funktion som den en gång gjorde. I Sverige är Myndigheten för samhällsskydd och beredskap (MSB) den myndighet som ansvarar för skyddsrummens tillstånd. MSB har det yttersta ansvaret att se till att skyddsrummen är säkra i nödsituationer. För att uppfylla detta utgör de tillsyn och kontroller på skyddsrummen. I denna kandidatuppsats undersöks de svenska skyddsrummens tillstånd och de problem som följer med dem. Vi fann det även av intresse att undersöka skyddsrummens relevans i Sveriges samhälle ur ett historiskt- och ett nutidsperspektiv. Metoden som har använts är av kvalitativ och rättsdogmatisk karaktär. De slutsatser som kunnat dras i denna kandidatuppsats är att Sveriges skyddsrum befinner sig i olika tillstånd vad gäller skick och kvalité. Det kan också konstateras att det inte pågår tillräckligt många skyddsrumskontroller som både är önskat och nödvändigt gentemot det stora antal skyddsrum som finns. Slutligen nyttjas Sveriges skyddsrum för andra ändamål än vad de preliminärt byggdes för, vilket innebär att de fyller ett syfte i Sveriges samhälle. / In 2002, the Swedish government decided to stop building air raid shelters. Sweden has per capita the second most air raid shelters in the world. A large number of air raid shelters in Sweden, combined with the decision to stop constructing them, has left Sweden at a crossroad. How much should Sweden care about the air raid shelters? To foreign enemies, the air raid shelters may seem as yet another obstacle to invading, because of the opportunity given to the Swedish civilians to be safe from bombs and the effects of war. Even though the warfare has changed during the years and new strategies have been developed, a safe place for civilians will strengthen the defending side. For this defense to work, the air raid shelters have to be constructed at available locations for civilians, be equipped with the material needed, be operated by a civilian and the shelters have to be in good condition. It was during the Cold War era that Sweden built most of its air raid shelters. With a lot of decades and different rules of construction passing, many of these air raid shelters have problems now. The problems concern materials missing, air filters which have passed their best before date, the shelters being renovated to something completely different, or simply that the shelter cannot guarantee the function that it once did. In Sweden, The Swedish Civil Contingencies Agency (MSB) is the agency responsible for the condition of the air raid shelters. The agency has the utmost responsibility that the air raid shelters will be safe in case of emergency. To fulfill that, the agency executes supervision and regulatory control of the shelters. In this essay, the condition of the Swedish air raid shelters and the problems that come along with them get examined. We also found it interesting to examine the air raid shelters' relevance to Swedish society from a historic and present-day point of view. A qualitative and legal dogmatic method has been used. The conclusions that could be drawn from this essay is that Sweden’s air raid shelters are in different conditions regarding standard and quality. It can also be established that there aren’t enough regulatory controls being executed. Finally, the Swedish air raid shelters do serve a purpose for the Swedish society even though they have been built for other reasons.

Mémoire numérisé par la Division de la gestion de documents et des archives de l'Université de Montréal

Reliability modelling of RAID storage systems with its various components such as RAID controllers, enclosures, expanders, interconnects and disks is important from a storage system designer's point of view. A model that can express all the failure characteristics of the whole RAID storage system can be used to evaluate design choices, perform cost reliability trade-offs and conduct sensitivity analyses. We present a reliability model for RAID storage systems where we try to model all the components as accurately as possible. We use several state-space reduction techniques, such as aggregating all in-series components and hierarchical decomposition, to reduce the size of our model. To automate computation of reliability, we use the PRISM model checker as a CTMC solver where appropriate. Initially, we assume a simple 3-state disk reliability model with independent disk failures. Later, we assume a Weibull model for the disks; we also consider a correlated disk failure model to check correspondence with the field data available. For all other components in the system, we assume exponential failure distribution. To use the CTMC solver, we approximate the Weibull distribution for a disk using sum of exponentials and we first confirm that this model gives results that are in reasonably good agreement with those from the sequential Monte Carlo simulation methods for RAID disk subsystems. Next, our model for whole RAID storage systems (that includes, for example, disks, expanders, enclosures) uses Weibull distributions and, where appropriate, correlated failure modes for disks, and exponential distributions with independent failure modes for all other components. Since the CTMC solver cannot handle the size of the resulting models, we solve such models using hierarchical decomposition technique. We are able to model fairly large configurations with upto 600 disks using this model. We can use such reasonably complete models to conduct several "what-if" analyses for many RAID storage systems of interest. Our results show that, depending on the configuration, spanning a RAID group across enclosures may increase or decrease reliability. Another key finding from our model results is that redundancy mechanisms such as multipathing is beneficial only if a single failure of some other component does not cause data inaccessibility of a whole RAID group.

Mémoire numérisé par la Division de la gestion de documents et des archives de l'Université de Montréal.

International Telemetering Conference Proceedings / October 23-26, 2000 / Town & Country Hotel and Conference Center, San Diego, California / For the last 30 years Magnetic Tape Systems have been the primary means of recording data from airborne instrumentation systems. Increasing data rates and harsh environmental requirements have often exceeded the ability of tape-based systems to keep pace with technology. Throughout this time data recordings have been made mostly with analog longitudinal systems and most recently with digital recording systems that record on commercial DLT, and super VHS tape media. The recordings are played back with the same type of tape device allowing for the data to be processed and/or archived. Since not all data reduction facilities can process the same type of tape media, often tapes are dubbed from one type of tape media format to another, corrupting the translated data. This paper examines operational and data reduction benefits, and life cycle cost of Solid State Recorders as a replacement for existing airborne tape recorders.

International Telemetering Conference Proceedings / October 25-28, 1999 / Riviera Hotel and Convention Center, Las Vegas, Nevada / Today’s large-scale signal processing systems impose massive bandwidth requirements on both internal and external communication systems. Most often, these bandwidth requirements are met by scalable input/output architectures built around high-performance, standards-based technology. Several such technologies are available and are in common use as internal and/or external communication mechanisms. This paper provides an overview of some of the more common scalable technologies used for internal and external communications in real-time data acquisition systems. With respect to internal communications mechanisms this paper focuses on three ANSI-standard switched fabric technologies: RACEway (ANSI/VITA 5-1994), SKYchannel (ANSI/VITA 10-1995) and Myrinet (ANSI/VITA 26-1998). The discussion then turns to how Fibre Channel, HiPPI, and ATM are used to provide scalable external communications in real-time systems. Finally, glimpse of how these technologies are evolving to meet tomorrow’s requirements is provided.

International Telemetering Conference Proceedings / October 23-26, 2000 / Town & Country Hotel and Conference Center, San Diego, California / Flexible data multiplexing that supports both low-speed (4 Mbps) to very high-speed output devices (networks and recording systems up to 480 Mbps), along with data network formatting, can greatly enhance the results of range upgrading.