...FAILURES POSS / 355 Moore Clarence 29 june 2015 BOB O CONNER To begin what is a distributed system? There are several words that can describe parts that make up a distributed system. A program , a process, a message, packet, protocol, network components all take part in helping define what a distributed system makes of. A distributed system is an application that executes a collection of protocols to coordinate cooperate together to perform a single or small set of related tasks. Failure is the defining difference between distributed and local programming. So you have to design distributed system with the expectation of failures. Handling failures is an important theme in distributed systems design. Failures fall into two obvious categories. Hardware and software. Hardware failures was once an issue but since has improved a lot. Dealing with a lot of improvements to such items as wiring and circuits played positive roles to improving hardware the mechanical and network failures are part of todays problems. Software failures is part of a distributed system. When a software failure occurs it often affect downtime to the distributed system. The computer freezing or fail stop and so often even a network failure. Types of failures includes crash failures that is when a server halts, but its working correctly until it halts. Omission failure is another type of failure that a server fails to respond to incoming requests also fails to receive incoming messages or fails to...
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...Crash failures are caused across the server of a typical distributed system and if these failures are occurred operations of the server are halt for some time. Operating system failures are the best examples for this case and the corresponding fault tolerant systems are developed with respect to these affects. Timing failures: Timing failures are caused across the server of a distributed system. The usual behavior of these timing failures would be like that the server response time towards the client requests would be more than the expected range. Control flow out of the responses may be caused due to these timing failures and the corresponding clients may give up as they can’t wait for the required response from the server and thus the server operations are failed due to this. Omission failures: Omission failures are caused across the server due to lack or reply or response from the server across the distributed systems. There are different issues raised due to these omission failures and the key among them are server not listening or a typical buffer overflow errors across the servers of the distributed systems. Byzantine failures: Byzantine failures are also know as arbitrary failures and these failures are caused across the server of the distributed systems. These failures cause the server to behave arbitrary in nature and the server responds in an arbitrary passion at arbitrary times across the distributed systems. Output from the server would be inappropriate...
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...POS/355 March 11, 2013 Bhupinder Singh Failures Paper The distributed systems are unique in that it’s executions of the application of the protocols are to coordinate on multiple processes on the network, they have their own local memory and it communicates in entities with each of them using a massage passing mechanism. They also have their own personal users to them that they can use for personal uses. What are shared across the distributed systems are the data, processor, and the memory that can achieve those tasks when processing information. The distributed system has features to help achieve in in solving problems and issues with software and programs, when being useful with the distributed system is not very easy; its capabilities are the components, than just the stand alone systems that are sometimes not as reliable. Because of the complexities of interactions between running the distributed systems, it must have special characteristics like the fault tolerant; this can recover from component failures without performing incorrect actions. Recoverable is where failed components can restart and then rejoin the system after the cause failure has been repaired. The failure on a distributed system can result in anything from easily repairable errors to a catastrophic meltdown. Fault tolerance deals with making the system function in the presence of defaults. Faults can occur in any one of components. In this paper we will look at the different...
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...Four Types of Distributed Computer System Failures University of Phoenix August 19, 2013 David Conway Four Types of Distributed Computer System Failures This paper will discuss four common types of distributed computer system failures which are Crash failures also known as operating system failures, Hardware Failures, Omission Failures and Byzantine Failures. Included in the discussion are failures which can also occur in a centralized computer system, and how to isolate and repair two types of failures. Crash failures are normally associated with a server fault in a typical distributed system. Inherently crash failures are interrupt operations of the server and can halt operation for a considerable time (Projects Helper, 2012).Operating system failures are the best examples for this scenario. Operating System or software failures come in many more varieties than hardware failures. Software bugs in distributed systems can be difficult to replicate and, consequently, repair and or debug. Corresponding fault tolerant systems are developed and employed with respect to these affects. An operating system or software failure can also occur in a centralized system such as a data base this is why it is highly recommended to back up a data base using stable mass storage media (Projects Helper, 2012). We have an extensive...
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...this grid a definition with self-healing, security, integration, collaborative, forecast, optimization and interaction. While European commission define it as : A grid which could support distributed and renewable energy access, supply more reliable and secure electricity, have a service-oriented architecture and flexible grid applications, possess an advanced automation and distributed intelligent, be able to local interact the load and the power, adhere to customer centric. Obviously, these definitions has been formulated for the future of power industry mainly focusing on world today’s energy generation, transmission, distribution limitation & changing consumer trends. Recently world has observed a series of blackout, partial power failure and this compelled the world’s nations to go for an ideal grid system that is smart enough to face such kind of challenges. This has resulted the unification of power system with the information technology & modren telecommunition setup. And SELF HEALING become the key component of smart grid, as smart grid should possess an intelligent control funtion, which could rapidly isolate and self recover the fault, prevent the occurance of balckout and improve the reliability of grid operation with minimum human intervention & consume distributed generation too. Background: An especially illuminating event occurred in 1879 when Thomos Edison invented what is considered to be the precursor of modern light bulb. Three years...
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...The University Student Registration System: a Case Study in Building a High-Availability Distributed Application Using General Purpose Components M. C. Little, S. M. Wheater, D. B. Ingham, C. R. Snow, H. Whitfield and S. K. Shrivastava Department of Computing Science, Newcastle University, Newcastle upon Tyne, NE1 7RU, England. Abstract Prior to 1994, student registration at Newcastle University involved students being registered in a single place, where they would present a form which had previously been filled in by the student and their department. After registration this information was then transferred to a computerised format. The University decided that the entire registration process was to be computerised for the Autumn of 1994, with the admission and registration being carried out at the departments of the students. Such a system has a very high availability requirement: admissions tutors and secretaries must be able to access and create student records (particularly at the start of a new academic year when new students arrive). The Arjuna distributed system has been under development in the Department of Computing Science for many years. Arjuna’s design aims are to provide tools to assist in the construction of fault-tolerant, highly available distributed applications using atomic actions (atomic transactions) and replication. Arjuna offers the right set of facilities for this application, and its deployment would enable the University to exploit the existing...
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...Distributed Query Scheduling Service: An Architecture and Its Implementation Ling Liu and Calton Pu Oregon Graduate Institute Department of Computer Science & Engineering P.O.Box 91000 Portland Oregon 97291-1000 USA flingliu,caltong@cse.ogi.edu Kirill Richine University of Alberta Department of Computer Science GSB615, Edmonton T6G2H1 AB, Canada kirill@cs.ualberta.ca Abstract We present the systematic design and development of a distributed query scheduling service (DQS) in the context of DIOM, a distributed and interoperable query mediation system 26]. DQS consists of an extensible architecture for distributed query processing, a three-phase optimization algorithm for generating e cient query execution schedules, and a prototype implementation. Functionally, two important execution models of distributed queries, namely moving query to data or moving data to query, are supported and combined into a uni ed framework, allowing the data sources with limited search and ltering capabilities to be incorporated through wrappers into the distributed query scheduling process. Algorithmically, conventional optimization factors (such as join order) are considered separately from and re ned by distributed system factors (such as data distribution, execution location, heterogeneous host capabilities), allowing for stepwise re nement through three optimization phases: compilation, parallelization, site selection and execution. A subset of DQS algorithms has been...
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... |: |HND | |SEMESTER |: |04 | |UNIT NO./TITLE |: |35/ Distributed Design and Development | |ASSIGNMENT NO. |: |01 | |ASSIGNMENT TITLE |: |City Bank Distributed Design System | |UNIT OUTCOMES COVERED |: | | | 35.1 Understand Microsoft architecture for enterprise applications | |35.2 Design a distributed application | |35.3 Build a distributed application | |35.4 Build and use components | |ASSIGNMENT TYPE ...
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...A distributed system is a collection of processors that run a single system, but may act independently. The processors on a distributed system can be on a single computer or multiple computers and can be spread across a local or wide area network. With this type of systems, potential problems can arise. The following will address some of these problems. Network Failure One problem that may arise in a distributed system is a failure within the network. The processors on a distributed system must communicate with each other over a network and failure to do so could cause problems with the function needing to be carried out. In order to fix this problem, you would need to find out which end the problem is originating from. This can be done by checking the data sent by all the processors and seeing if the data is being sent correctly. This will help to determine whether or not the problem is in the sending of the data or the receiving of the data within the network. After isolating the source of the problem, it can be addressed appropriately. Timing Failure A timing failure can occur when processors on the network are not synchronized. When processors are not synchronized, then processes that require two or more processors might become delayed or fail all together. For instance, if a process the uses multiple processors is schedule to occur at noon and one of the processors’ clock is a couple minutes fast, that processor will start the process too early which could result in a...
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...Middleware for Distributed Systems Evolving the Common Structure for Network-centric Applications Richard E. Schantz BBN Technologies 10 Moulton Street Cambridge, MA 02138, USA schantz@bbn.com Douglas C. Schmidt Electrical & Computer Engineering Dept. University of California, Irvine Irvine, CA 92697-2625, USA schmidt@uci.edu 1 Overview of Trends, Challenges, and Opportunities Two fundamental trends influence the way we conceive and construct new computing and information systems. The first is that information technology of all forms is becoming highly commoditized i.e., hardware and software artifacts are getting faster, cheaper, and better at a relatively predictable rate. The second is the growing acceptance of a network-centric paradigm, where distributed applications with a range of quality of service (QoS) needs are constructed by integrating separate components connected by various forms of communication services. The nature of this interconnection can range from 1. The very small and tightly coupled, such as avionics mission computing systems to 2. The very large and loosely coupled, such as global telecommunications systems. The interplay of these two trends has yielded new architectural concepts and services embodying layers of middleware. These layers are interposed between applications and commonly available hardware and software infrastructure to make it feasible, easier, and more cost effective to develop and evolve systems using reusable software. Middleware...
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...Failures The following paper will examine four types of failures that may occur in a distributed system. Also discussed is how these failures relate to a centralized system. Lastly, two of the four failures common to both a distributed and a centralized system will be isolated and fixed. A distributed operating system gives the appearance of a single system; however in all actuality it is a collection of computers that are connected to a network. This collection of computers, or distributed operating system, share resources and therefore encounters problematic failures as a result (Stallings, 2012). Failures experienced by distributed operating systems include communication faults, machine failures or fail-stop, storage-device crashes and decays of storage media, and network failures (Ghosh & Mathur, 2011). Communication faults In order to detect communication faults a time-out scheme can be used. When a communication, or message, is sent out it specifies a time interval during specifying the length of time it will wait for an acknowledgement message from the sender. If the sender received the acknowledgement message within the specified timeframe, then all is well and good. However, if the message is outside of that timeframe then we know that we are experiencing a communication fault and a time-out is occurring. In this case, the sender can send a message to the receiver asking ‘are you up?’. If no response is acknowledged or sent back, then it is likely...
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...SECURITY ORIENTED COMPUTING This refers to components of organizational security programs that ate put in place to ensure the safeguarding of an organization’s framework. They play quite a significant role in preventing cybercrime or manipulation of an organizations data. They are not necessarily focused on Information technology but rather are concepts that have been put to the test and proved to be viable. One of this concepts is security oriented computing. It can be best described as a strategy to prepare for unavoidable failures. It is a slight alteration from the principle known as recovery oriented computing. Both concepts revolve around the ideology that accidents are anticipated in key aspects and will occur at one point .Security oriented computing operates on a number of principles that ensure its effectiveness. One of this assumptions is that all security controls are vulnerable and may end up causing inaccessibility of the intended service or even worse, unauthorized users. This helps the particular organization be on high alert and ensure that their security controls are monitored at all times .Another assumption is that all people conducting alterations or configurations to the system may introduce loopholes to the latter due to wrongful installation or a mistake made during the configuration. The third assumption is that all people conducting day to day operations are subject to make normal errors if the computer allows them to. Interfacing with humans creates...
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...deployment is usually built on a robust architecture thus providing resiliency and redundancy to its users. The cloud offered automatic failover between hardware platforms out of the box, while disaster recovery services are also often included. The processing that used to take more than 2 week could be done by KinCare within 30 seconds due to the use of cloud computing this improved the efficiency of the workers in the company. 5. Scalability and Performance Cloud instances are deployed automatically only when needed and as a result, you pay only for the applications and data storage you need. Hand in hand, also comes elasticity, since clouds can be scaled to meet your changing IT system demands. Regarding performance, the systems utilize distributed architectures which offer excellent speed of computations. 6. Quick deployment and ease of integration From the cloud system which can be up and running in a very short period, making quick deployment a key benefit. On the same aspect, the introduction of a new user in the system happens instantaneously, eliminating waiting periods. 7. Increased Storage...
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...A distributed system is a collection of processors that run a single system, but may act independently. The processors on a distributed system can be on a single computer or multiple computers and can be spread across a local or wide area network. With this type of systems, potential problems can arise. The following will address some of these problems. Network Failure One problem that may arise in a distributed system is a failure within the network. The processors on a distributed system must communicate with each other over a network and failure to do so could cause problems with the function needing to be carried out. In order to fix this problem, you would need to find out which end the problem is originating from. This can be done by checking the data sent by all the processors and seeing if the data is being sent correctly. This will help to determine whether or not the problem is in the sending of the data or the receiving of the data within the network. After isolating the source of the problem, it can be addressed appropriately. Timing Failure A timing failure can occur when processors on the network are not synchronized. When processors are not synchronized, then processes that require two or more processors might become delayed or fail all together. For instance, if a process the uses multiple processors is schedule to occur at noon and one of the processors’ clock is a couple minutes fast, that processor will start the process too early which could result in...
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...Failures POS/355 August 26, 2013 UOPX Failures Distributed systems emerged recently in the world of computers. A distributed system is an application of independent computers that appear to work as a coherent system to its users. The advantages of distributed systems consist of developing the ability to continually to open interactions with other components to accommodate a number of computers and users. Thus, stating that a stand-alone system is not as powerful as a distributed system that has the combined capabilities of distributed components. This type of system does have its complications and is difficult to maintain complex interactions continual between running components. Problems do arise because distributed systems are not without its failures. Four types of failures will characterize and the solutions to two of these failures will address on how to fix such problems. Before constructing a distributed system reliable one must consider fault tolerance, availability, reliability, scalability, performance, and security. Fault tolerance means that the system continues to operate in the event of internal or external system failure to prevent data loss or other issues. Availability needed to restore operations to resume procedure with components has failed to perform. For the system to run over a long period without any errors is need and known as reliability. To remain scalable means to operate correctly on a large scale. Performance and security remains needed...
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