scholarly journals RemusDB: transparent high availability for database systems

2012 ◽  
Vol 22 (1) ◽  
pp. 29-45 ◽  
Author(s):  
Umar Farooq Minhas ◽  
Shriram Rajagopalan ◽  
Brendan Cully ◽  
Ashraf Aboulnaga ◽  
Kenneth Salem ◽  
...  
Keyword(s):  
Database Systems ◽  
High Availability

Highly Available Database Management Systems

2009 ◽  
pp. 28-34
Author(s):  
Wenbing Zhao
Keyword(s):  
Database Management ◽  
Database Systems ◽  
Database Management Systems ◽  
High Availability ◽  
Management Systems ◽  
Database Replication ◽  
The Subject ◽  
Database Clustering ◽  
Alternative Solutions

The subject of highly available database systems has been studied for more than two decades, and there exist many alternative solutions (Agrawal, El Abbadi, & Steinke, 1997; Kemme, & Alonso, 2000; Patino-Martinez, Jimenez-Peris, Kemme, & Alonso, 2005). In this article, we provide an overview of two of the most popular database high availability strategies, namely database replication and database clustering. The emphasis is given to those that have been adopted and implemented by major database management systems (Davies & Fisk, 2006; Ault & Tumma, 2003).

High Availability and Data Consistency for Three-Tier Enterprise Applications

2011 ◽  
pp. 552-558
Author(s):  
Wenbing Zhao ◽  
Louise E. Moser ◽  
P. Michael Melliar-Smith
Keyword(s):  
Programming Model ◽  
Database Systems ◽  
Transaction Processing ◽  
High Availability ◽  
Data Consistency ◽  
Middle Tier ◽  
Enterprise Applications ◽  
Long Time ◽  
Critical Components ◽  
Server Application

Enterprise applications, such as those for e-commerce and e-government, are becoming more and more critical to our economy and society. Such applications need to provide continuous service, 24 hours a day, 7 days a week. Any disruption in service, including both planned and unplanned downtime, can result in negative financial and social effects. Consequently, high availability and data consistency are critically important for enterprise applications. Enterprise applications are typically implemented as three-tier applications. A three-tier application consists of clients in the front tier, servers that perform the business logic processing in the middle tier, and database systems that store the application data in the backend tier, as shown in Figure 1. Within the middle tier, a server application typically uses a transaction processing programming model. When a server application receives a client’s request, it initiates one or more transactions, which often are distributed transactions. When it finishes processing the request, the server application commits the transaction, stores the resulting state in the backend database, and returns the result to the client. A fault in the middle tier might cause the abort of a transaction and/or prevent the client from knowing the outcome of the transaction. A fault in the backend tier has similar consequences. In some cases, the problems can be a lot worse. For example, a software design fault, or an inappropriate heuristic decision, might introduce inconsistency in the data stored in the database, which can take a long time to fix. Two alternative recovery strategies, namely roll-backward and roll-forward, can be employed to tolerate and recover from a fault. In roll-backward recovery, the state of the application that has been modified by a set of unfinished operations is reversed by restoring it to a previous consistent state. This strategy is used in transaction processing systems. In roll-forward recovery, critical components, processes, or objects are replicated on multiple computers so that if one of the replicas fails, the other replicas continue to provide service, which enables the system to advance despite the fault. Many applications that require continuous availability take the roll-forward approach. Replication is commonly employed in the backend tier to increase the reliability of the database system. There has been intense research (Frolund & Guerraoui, 2002; Zhao, Moser, & Melliar-Smith, 2005a) on the seamless integration of the roll-backward and roll-forward strategies in software infrastructures for three-tier enterprise applications, to achieve high availability and data consistency. High availability is a measure of the uptime of a system, and typically means five nines (99.999%) or better, which corresponds to 5.25 minutes of planned and unplanned downtime per year. Data consistency means that the application state stored in the database remains consistent after a transaction commits. Both transactions and replication require consistency, as the applications execute operations that change their states. Transactions require data consistency, and replication requires replica consistency.

A Survey on Database Performance in Virtualized Cloud Environments

2012 ◽  
Vol 8 (3) ◽  
pp. 1-26 ◽  
Author(s):  
Todor Ivanov ◽  
Ilia Petrov ◽  
Alejandro Buchmann
Keyword(s):  
Cloud Computing ◽  
Load Balancing ◽  
Resource Utilization ◽  
Database Systems ◽  
High Availability ◽  
Feed Processing ◽  
Computing Platform ◽  
Efficient Resource ◽  
Cloud Environments ◽  
Column Stores

Cloud Computing emerged as a major paradigm over the years. Major challenges it poses to computer science are related to latency, scale, and reliability issues. It leverages strong economical aspects and provides sound answers to questions like energy consumption, high availability, elasticity, or efficient computing resource utilization. Many Cloud Computing platform and solution providers resort to virtualization as key underlying technology. Properties like isolation, multi-virtual machine parallelism, load balancing, efficient resource utilization, and dynamic pre-allocation besides economic factors make it attractive. It not only legitimates the spread of several types of data stores supporting a variety of data modes, but also inherently requires different types of load: (i) analytical; (ii) Transactional/Update-intensive; and (iii) mixed real-time feed processing. The authors survey how database systems can best leverage virtualization properties in cloud scenarios. The authors show that read mostly database systems and especially column stores profit from virtualization in analytical and search scenarios. Secondly, cloud analytics virtualized database systems are efficient in transactional scenarios such as Cloud CRM virtualized database systems lag. The authors also explore how the nature of mixed cloud loads can be best reflected by virtualization properties like load balancing, migration, and high availability.

Intelligent Processing of Loosely Structured Documents as a Strategy for Organizing Electronic Health Care Records

1993 ◽  
Vol 32 (04) ◽  
pp. 265-268 ◽  
Author(s):  
D. J. Essin
Keyword(s):  
Health Care ◽  
Health Care Organization ◽  
Database Systems ◽  
Relevant Information ◽  
Full Potential ◽  
Care Organization ◽  
Intelligent Processing ◽  
Data Interchange ◽  
Structured Documents ◽  
Health Care Records

AbstractLoosely structured documents can capture more relevant information about medical events than is possible using today’s popular databases. In order to realize the full potential of this increased information content, techniques will be required that go beyond the static mapping of stored data into a single, rigid data model. Through intelligent processing, loosely structured documents can become a rich source of detailed data about actual events that can support the wide variety of applications needed to run a health-care organization, document medical care or conduct research. Abstraction and indirection are the means by which dynamic data models and intelligent processing are introduced into database systems. A system designed around loosely structured documents can evolve gracefully while preserving the integrity of the stored data. The ability to identify and locate the information contained within documents offers new opportunities to exchange data that can replace more rigid standards of data interchange.

Data Security in Health Information Systems by Applying Software Techniques

1979 ◽  
Vol 18 (04) ◽  
pp. 214-222
Author(s):  
K. Sauter
Keyword(s):  
Information Systems ◽  
Health Information ◽  
Data Security ◽  
Health Information Systems ◽  
Database Systems ◽  
Modern Computer ◽  
Proper Design ◽  
Software Construction ◽  
Organizational Procedures ◽  
Software Measures

The problems encountered in achieving data security within computer-supported information systems increased with the development of modern computer systems. The threats are manifold and have to be met by an appropriate set of hardware precautions, organizational procedures and software measures which are the topic of this paper. Design principles and software construction rules are treated first, since the security power of a system is considerably determined by its proper design. A number of software techniques presented may support security mechanisms ranging from user identification and authentication to access control, auditing and threat monitoring. Encryption is a powerful tool for protecting data during physical storage and transmission as well.Since an increasing number of health information systems with information-integrating functions are database-supported, the main issues and terms of database systems and their specific security aspects are summarized in the appendix.

HALR: A TCP Enhancement Scheme Using Local Caching in High-Availability Cluster

2009 ◽  
Vol E92-B (1) ◽  
pp. 26-33
Author(s):  
Yi-Hsuan FENG ◽  
Nen-Fu HUANG ◽  
Yen-Min WU
Keyword(s):  
High Availability

Performance Evaluation of Distributed Database Systems

2014 ◽  
Vol 13 (9) ◽  
pp. 4859-4867
Author(s):  
Khaled Saleh Maabreh
Keyword(s):  
Performance Evaluation ◽  
System Performance ◽  
Operation Mode ◽  
Database Systems ◽  
Distributed Database ◽  
Evaluation Study ◽  
Distributed Database Systems ◽  
Different Types ◽  
Distributed Database System ◽  
Distributed Database Management

Distributed database management systems manage a huge amount of data as well as large and increasingly growing number of users through different types of queries. Therefore, efficient methods for accessing these data volumes will be required to provide a high and an acceptable level of system performance.  Data in these systems are varying in terms of types from texts to images, audios and videos that must be available through an optimized level of replication. Distributed database systems have many parameters like data distribution degree, operation mode and the number of sites and replication. These parameters have played a major role in any performance evaluation study. This paper investigates the main parameters that may affect the system performance, which may help with configuring the distributed database system for enhancing the overall system performance.

CRITICAL STUDY ON DATABASE AND PROMINENT PROGRAMMES

2013 ◽  
Vol 4 (1) ◽  
pp. 44-47
Author(s):  
Dr. Vinod Kumar ◽  
Gagandeep Raheja ◽  
Sukhpreet Singh
Keyword(s):  
Human Brain ◽  
Everyday Life ◽  
Modern Society ◽  
Database Systems ◽  
Simple Device ◽  
Critical Study ◽  
Essential Component ◽  
The People

The people who work with computers, the programmers, analysts, and operators who seem to live by rules of their own and seldom leave their own environment, tend to be very cynical towards the stories of electronic brains. This attitude will appear hardly surprising when one eventually learns that the computer is a very simple device and is as far removed from an electronic brain as a bicycle from a spaceship. Programmers in particular are the people most aware that computers are no substitute for the human brain; in fact, the preparation of work to be run on a computer can be one of the most mind-bending exercises encountered in everyday life. Databases and database systems have become an essential component of everyday life in modern society. In the course of a day, most of us encounter several activities that involve some interaction with a database. So in this paper we will talk about how to manage the different type of data involved in any form in the database.

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