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Elasticity (cloud Computing)
In cloud computing, elasticity is defined as "the degree to which a system is able to adapt to workload changes by provisioning and de-provisioning resources in an autonomic manner, such that at each point in time the available resources match the current demand as closely as possible". Elasticity is a defining characteristic that differentiates cloud computing from previously proposed computing paradigms, such as grid computing. The dynamic adaptation of capacity, e.g., by altering the use of computing resources, to meet a varying workload is called "elastic computing". Example Let us illustrate elasticity through a simple example of a service provider who wants to run a website on an IaaS cloud. At moment t_0, the website is unpopular and a single machine (most commonly a virtual machine) is sufficient to serve all web users. At moment t_1, the website suddenly becomes popular, for example, as a result of a flash crowd, and a single machine is no longer sufficient to serve all us ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cloud Computing
Cloud computing is the on-demand availability of computer system resources, especially data storage ( cloud storage) and computing power, without direct active management by the user. Large clouds often have functions distributed over multiple locations, each of which is a data center. Cloud computing relies on sharing of resources to achieve coherence and typically uses a "pay as you go" model, which can help in reducing capital expenses but may also lead to unexpected operating expenses for users. Value proposition Advocates of public and hybrid clouds claim that cloud computing allows companies to avoid or minimize up-front IT infrastructure costs. Proponents also claim that cloud computing allows enterprises to get their applications up and running faster, with improved manageability and less maintenance, and that it enables IT teams to more rapidly adjust resources to meet fluctuating and unpredictable demand, providing burst computing capability: high computing p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Grid Computing
Grid computing is the use of widely distributed computer resources to reach a common goal. A computing grid can be thought of as a distributed system with non-interactive workloads that involve many files. Grid computing is distinguished from conventional high-performance computing systems such as cluster computing in that grid computers have each node set to perform a different task/application. Grid computers also tend to be more heterogeneous and geographically dispersed (thus not physically coupled) than cluster computers. Although a single grid can be dedicated to a particular application, commonly a grid is used for a variety of purposes. Grids are often constructed with general-purpose grid middleware software libraries. Grid sizes can be quite large. Grids are a form of distributed computing composed of many networked loosely coupled computers acting together to perform large tasks. For certain applications, distributed or grid computing can be seen as a special type of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Website
A website (also written as a web site) is a collection of web pages and related content that is identified by a common domain name and published on at least one web server. Examples of notable websites are Google Search, Google, Facebook, Amazon (website), Amazon, and Wikipedia. All publicly accessible websites collectively constitute the World Wide Web. There are also private websites that can only be accessed on a intranet, private network, such as a company's internal website for its employees. Websites are typically dedicated to a particular topic or purpose, such as news, education, commerce, entertainment or social networking. Hyperlinking between web pages guides the navigation of the site, which often starts with a home page. User (computing), Users can access websites on a range of devices, including desktop computer, desktops, laptops, tablet computer, tablets, and smartphones. The application software, app used on these devices is called a Web browser. History ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
IaaS
The first major provider of infrastructure as a service (IaaS) was Amazon in 2008. IaaS is a cloud computing service model by means of which computing resources are supplied by a cloud services provider. The IaaS vendor provides the storage, network, servers and virtualization (which mostly refers, in this case, to emulating computer hardware). This service enable users to free themselves from maintaining an on-premise data center. The IaaS provider is hosting these resources in either a public cloud (meaning users share the same hardware, storage, and network devices with other users), private cloud (meaning users does not share these resources), or hybrid cloud (combination of both). It provides the customer with high-level APIs used to dereference various low-level details of underlying network infrastructure like backup, data partitioning, scaling, security, physical computing resources, etc. A hypervisor, such as Xen, Oracle VirtualBox, Oracle VM, KVM, VMware ESX/ESXi, or ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Virtual Machine
In computing, a virtual machine (VM) is the virtualization/emulation of a computer system. Virtual machines are based on computer architectures and provide functionality of a physical computer. Their implementations may involve specialized hardware, software, or a combination. Virtual machines differ and are organized by their function, shown here: * '' System virtual machines'' (also termed full virtualization VMs) provide a substitute for a real machine. They provide functionality needed to execute entire operating systems. A hypervisor uses native execution to share and manage hardware, allowing for multiple environments which are isolated from one another, yet exist on the same physical machine. Modern hypervisors use hardware-assisted virtualization, virtualization-specific hardware, primarily from the host CPUs. * Process virtual machines are designed to execute computer programs in a platform-independent environment. Some virtual machine emulators, such as QEMU and video ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Flash Crowd
"Flash Crowd" is a 1973 English-language novella by science fiction author Larry Niven, one of a series about the social consequence of inventing an instant, practically free displacement booth. One consequence not foreseen by the builders of the system was that with the almost immediate reporting of newsworthy events, tens of thousands of people worldwide – along with criminals – would teleport to the scene of anything interesting, thus creating disorder and confusion. The plot centers around a television journalist who, after being fired for his inadvertent role in inciting a post-robbery riot in Los Angeles, seeks to independently investigate the teleportation system for the flaws in its design allowing for such spontaneous riots to occur. His investigation takes him to destinations and people around the world within the matter of less than 12 hours before he gets his chance to plead his case on television, and he encounters the wide-ranging effects of displacements upon ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Web Server
A web server is computer software and underlying hardware that accepts requests via HTTP (the network protocol created to distribute web content) or its secure variant HTTPS. A user agent, commonly a web browser or web crawler, initiates communication by making a request for a web page or other resource using HTTP, and the server responds with the content of that resource or an error message. A web server can also accept and store resources sent from the user agent if configured to do so. The hardware used to run a web server can vary according to the volume of requests that it needs to handle. At the low end of the range are embedded systems, such as a router that runs a small web server as its configuration interface. A high-traffic Internet website might handle requests with hundreds of servers that run on racks of high-speed computers. A resource sent from a web server can be a preexisting file (static content) available to the web server, or it can be generated ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Amazon EC2
Amazon Elastic Compute Cloud (EC2) is a part of Amazon.com's cloud-computing platform, Amazon Web Services (AWS), that allows users to rent virtual computers on which to run their own computer applications. EC2 encourages scalable deployment of applications by providing a web service through which a user can boot an Amazon Machine Image (AMI) to configure a virtual machine, which Amazon calls an "instance", containing any software desired. A user can create, launch, and terminate server-instances as needed, paying by the second for active servershence the term "elastic". EC2 provides users with control over the geographical location of instances that allows for latency optimization and high levels of redundancy. In November 2010, Amazon switched its own retail website platform to EC2 and AWS. History Amazon announced a limited public beta test of EC2 on August 25, 2006, offering access on a first-come, first-served basis. Amazon added two new instance types (Large and Extra- ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Expenses
An expense is an item requiring an outflow of money, or any form of fortune in general, to another person or group as payment for an item, service, or other category of costs. For a tenant, rent is an expense. For students or parents, tuition is an expense. Buying food, clothing, furniture, or an automobile is often referred to as an expense. An expense is a cost that is "paid" or " remitted", usually in exchange for something of value. Something that seems to cost a great deal is "expensive". Something that seems to cost little is "inexpensive". "Expenses of the table" are expenses for dining, refreshments, a feast, etc. In accounting, ''expense'' is any specific outflow of cash or other valuable assets from a person or company to another person or company. This outflow is generally one side of a trade for products or services that have equal or better current or future value to the buyer than to the seller. Technically, an expense is an event in which a proprietary stake is dimi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Profit (accounting)
Profit, in accounting, is an income distributed to the ownership , owner in a Profit (economics) , profitable market production process (business). Profit is a measure of profitability which is the owner's major interest in the income-formation process of market production. There are several profit measures in common use. Income formation in market production is always a balance between income generation and income distribution. The income generated is always distributed to the Stakeholder (corporate), stakeholders of production as economic value within the review period. The profit is the share of income formation the owner is able to keep to themselves in the income distribution process. Profit is one of the major sources of economics , economic well-being because it means incomes and opportunities to develop production. The words "income", "profit" and "earnings" are synonyms in this context. Measurement of profit There are several important profit measures in common use. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Income
Income is the consumption and saving opportunity gained by an entity within a specified timeframe, which is generally expressed in monetary terms. Income is difficult to define conceptually and the definition may be different across fields. For example, a person's income in an economic sense may be different from their income as defined by law. An extremely important definition of income is Haig–Simons income, which defines income as ''Consumption + Change in net worth'' and is widely used in economics. For households and individuals in the United States, income is defined by tax law as a sum that includes any wage, salary, profit, interest payment, rent, or other form of earnings received in a calendar year.Case, K. & Fair, R. (2007). ''Principles of Economics''. Upper Saddle River, NJ: Pearson Education. p. 54. Discretionary income is often defined as gross income minus taxes and other deductions (e.g., mandatory pension contributions), and is widely used as a basis to co ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ganglia (software)
Ganglia is a scalable, distributed monitoring tool for high-performance computing systems, clusters and networks. The software is used to view either live or recorded statistics covering metrics such as CPU load averages or network utilization for many nodes. Ganglia software is bundled with enterprise-level Linux distributions such as Red Hat Enterprise Level (RHEL) or the CentOS repackaging of the same. Ganglia grew out of requirements for monitoring systems by Berkeley (University of California) but now sees use by commercial and educational organisations such as Cray, MIT, NASA and Twitter. Ganglia It is based on a hierarchical design targeted at federations of clusters. It relies on a multicast-based listen/announce protocol to monitor state within clusters and uses a tree of point-to-point connections amongst representative cluster nodes to federate clusters and aggregate their state. It leverages widely used technologies such as XML for data representation, XDR for com ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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