Persistent Buffer Management with Optimistic Consistency

Finding the best way to leverage non-volatile memory (NVM) on modern database systems is still an open problem. The answer is far from trivial since the clear boundary between memory and storage present in most systems seems to be incompatible with the intrinsic memory-storage duality of NVM. Rather than treating NVM either solely as memory or solely as storage, in this work we propose how NVM can be simultaneously used as both in the context of modern database systems. We design a persistent buffer pool on NVM, enabling pages to be directly read/written by the CPU (like memory) while recovering corrupted pages after a failure (like storage). The main benefits of our approach are an easy integration in the existing database architectures, reduced costs (by replacing DRAM with NVM), and faster peak-performance recovery

Leveraging Non-Volatile Memory in Modern Storage Management Architectures

Non-volatile memory technologies (NVM) introduce a novel class of devices that combine characteristics of both storage and main memory. Like storage, NVM is not only persistent, but also denser and cheaper than DRAM. Like DRAM, NVM is byte-addressable and has lower access latency. In recent years, NVM has gained a lot of attention both in academia and in the data management industry, with views ranging from skepticism to over excitement. Some critics claim that NVM is not cheap enough to replace flash-based SSDs nor is it fast enough to replace DRAM, while others see it simply as a storage device. Supporters of NVM have observed that its low latency and byte-addressability requires radical changes and a complete rewrite of storage management architectures. This thesis takes a moderate stance between these two views. We consider that, while NVM might not replace flash-based SSD or DRAM in the near future, it has the potential to reduce the gap between them. Furthermore, treating NVM as a regular storage media does not fully leverage its byte-addressability and low latency. On the other hand, completely redesigning systems to be NVM-centric is impractical. Proposals that attempt to leverage NVM to simplify storage management result in completely new architectures that face the same challenges that are already well-understood and addressed by the traditional architectures. Therefore, we take three common storage management architectures as a starting point, and propose incremental changes to enable them to better leverage NVM. First, in the context of log-structured merge-trees, we investigate the impact of storing data in NVM, and devise methods to enable small granularity accesses and NVM-aware caching policies. Second, in the context of B+Trees, we propose to extend the buffer pool and describe a technique based on the concept of optimistic consistency to handle corrupted pages in NVM. Third, we employ NVM to enable larger capacity and reduced costs in a index+log key-value store, and combine it with other techniques to build a system that achieves low tail latency. This thesis aims to describe and evaluate these techniques in order to enable storage management architectures to leverage NVM and achieve increased performance and lower costs, without major architectural changes.:1 Introduction 1.1 Non-Volatile Memory 1.2 Challenges 1.3 Non-Volatile Memory & Database Systems 1.4 Contributions and Outline 2 Background 2.1 Non-Volatile Memory 2.1.1 Types of NVM 2.1.2 Access Modes 2.1.3 Byte-addressability and Persistency 2.1.4 Performance 2.2 Related Work 2.3 Case Study: Persistent Tree Structures 2.3.1 Persistent Trees 2.3.2 Evaluation 3 Log-Structured Merge-Trees 3.1 LSM and NVM 3.2 LSM Architecture 3.2.1 LevelDB 3.3 Persistent Memory Environment 3.4 2Q Cache Policy for NVM 3.5 Evaluation 3.5.1 Write Performance 3.5.2 Read Performance 3.5.3 Mixed Workloads 3.6 Additional Case Study: RocksDB 3.6.1 Evaluation 4 B+Trees 4.1 B+Tree and NVM 4.1.1 Category #1: Buffer Extension 4.1.2 Category #2: DRAM Buffered Access 4.1.3 Category #3: Persistent Trees 4.2 Persistent Buffer Pool with Optimistic Consistency 4.2.1 Architecture and Assumptions 4.2.2 Embracing Corruption 4.3 Detecting Corruption 4.3.1 Embracing Corruption 4.4 Repairing Corruptions 4.5 Performance Evaluation and Expectations 4.5.1 Checksums Overhead 4.5.2 Runtime and Recovery 4.6 Discussion 5 Index+Log Key-Value Stores 5.1 The Case for Tail Latency 5.2 Goals and Overview 5.3 Execution Model 5.3.1 Reactive Systems and Actor Model 5.3.2 Message-Passing Communication 5.3.3 Cooperative Multitasking 5.4 Log-Structured Storage 5.5 Networking 5.6 Implementation Details 5.6.1 NVM Allocation on RStore 5.6.2 Log-Structured Storage and Indexing 5.6.3 Garbage Collection 5.6.4 Logging and Recovery 5.7 Systems Operations 5.8 Evaluation 5.8.1 Methodology 5.8.2 Environment 5.8.3 Other Systems 5.8.4 Throughput Scalability 5.8.5 Tail Latency 5.8.6 Scans 5.8.7 Memory Consumption 5.9 Related Work 6 Conclusion Bibliography A PiBenc

High incidence of Angina pectoris in patients treated with 5-fluorouracil - A planned surveillance study with 102 patients

Objective: Angina pectoris, arrhythmic sudden death and myocardial infarction, all these cardiac events have occasionally been reported during 5-fluorouracil (5-FU) chemotherapy. Underlying mechanisms leading to these events are unknown; damage to the myocytes or vasospasms have been discussed. Methods: 102 consecutive and unselected patients were monitored with 12-lead ECG, echocardiography and radionuclide ventriculography prior to the first cycle of 5-FU chemotherapy and 3 months from baseline. Results: 19% of the patients developed reversible symptoms of angina pectoris during treatment which lasted up to 12 h after cessation of the infusion. Most of the 19 patients showed corresponding ECG changes. 6 out of the 19 patients with severe angina pectoris had subsequent coronary angiography. In none of these patients the coronary angiography showed coronary artery disease, but it showed low ventricular function (ejection fraction <50%) in 2 patients. The ejection fraction did not increase overtime. Arrhythmias were screened for with Holter monitoring during 5-FU chemotherapy. The frequency of bradycardia and ventricular extrasystoles increased significantly (p < 0.05) during treatment compared to arrhythmias in Holter monitoring 3 months later. Furthermore the Qtc time in the ECG 3 months later was significantly prolonged (p < 0.05) compared to baseline values. Conclusions:The incidence of angina pectoris in patients during 5-FU treatment seems higher than previously suspected. As myocardial ischemia can be fatal, attentiveness to these symptoms and immediate treatment are crucial. Copyright (C) 2003 S. Karger AG, Basel

The presence of the Germanic ideas about urbanism at the School of Engineering from Porto Alegre, Brazil (1896 – 1930)

The main objective of this paper is to understand and discuss the role of the School of Engineering from Porto Alegre, between the years 1896 and 1930, as a channel for the introduction of ideas about the construction of cities, according to the urbanism widespread in Germany, from the mid-nineteenth century. Thus, the work brings to discussion the main ideas about the city and the urbanism developed in Germany to understand what led this nation to be a protagonist in a scenario constituted by problems caused by the industrialization process. The concept der Städtebau was used extensively in this context in reference to the new discipline on the construction of cities.In the case of Porto Alegre, a capital city of the State of Rio Grande do Sul in the South of Brazil, the paper presents its context, in the late nineteenth century and early twentieth century, trying to correlate the strong Germanic presence with the socio-economic development of the capital, as well as with its cultural exchanges. From this, the study adopts the School of Engineering from Porto Alegre and its engineers in the period of the Old Republic, as a means of conducting historical narrative, analyzing the correlations of the School, both with the Germanic presence, as with urban issues. In order to verify the presence of the Germanic ideas about urbanism throughout the School, the research investigates which ideas circulated, as well as the means or vehicles by which these ideas have come to it. The presence of original books like Der Städtebau nach seinen künstlerischen Grundsätzen from Camillo Sitte, for example, or volumes of the important Städtebauliche Vorträge aus dem Seminar für Städtebau at the Technischen Hochschule zu Berlin, organized by Joseph Brix and Felix Genzmer, were found at the library from the School of Engineering. Besides that, magazine’s articles at the EGATEA – the periodical of the School at that time - with the reinterpretation from Joseph Stübben’s speech were discovered and analyzed by the researcher. Furthermore the research identified at least two characters that, on one side, had contact with this Germanic ideology, while they studied at the Technischen Universität zu Berlin, and, on the other, established links with the School of Engineering. Finally, the text analyzes the contributions of these characters to the spreading of that ideology in Porto Alegre

Change in Personal Culture over the Life Course

Prior literature finds stability in personal culture, such as attitudes and values, in individuals’ life courses using short-running panel data. This work has concluded that lasting change in personal culture is rare after formative early years. This conclusion conflicts with a growing body of evidence for changes in personal culture after significant life course transitions, drawing on long-running panel data. To integrate these conflicting findings, the current study develops and applies a life course adaption model of personal culture, accounting for early imprinting and the continued possibility for change. Drawing on rich data from six long-running panel studies from five countries (BHPS, HILDA, PSID, SHP, SOEP, UKHLS) and 428 measures of personal culture, I test the theoretical expectations using mixed-effects modeling and an individual participant data meta-analysis. Results support the life course adaption model. Although lasting, non-transitory, within-individual changes in personal culture are relatively small compared to stable between-individual differences, I find strong support for the proposition that individuals change persistently in their personal culture as they move through the life course. These changes are partly dependent on prior biographical experiences. Finally, personal culture fluctuates substantially from year to year. Change in personal culture is increasingly varied for younger birth cohorts.Support Network for Interdisciplinary Social Policy Research (FIS)Peer Reviewe