Virtual Computers and Virtual Data Storage
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Virtual computers and virtual data storage Alen Šimec, Ognjen Staničić Tehnical Polytehnic in Zagreb/Vrbik 8, 10000 Zagreb, Croatia [email protected], [email protected] Abstract – Virtual data storage represents a new For the end user, virtual data storage brings lots of business model which includes various concepts benefits. Costs of hardware purchasing are such as virtualization, design of distributed eliminated, software licenses have been made applications and management which enables obsolete and there is no need for hiring new flexible data access. These methods include using employees. For these reasons virtual data storage networks of remote servers instead of local represents a big improvement in IT evolution servers and personal computers for storing, because it changes the business model. Access to managing and editing data. Locations containing data is unlimited and easily available from any servers which execute applications and store location worldwide. data are not strictly defined, hence terms “virtual data storage” or “storing data in the cloud” are used. As the need for storing data II.CONCEPT AND DEFINITION increased, managing that data became harder as well. Backing up data in large organizations is an inconvenient task. In spite of the increase in In the 1960s IBM introduces the concept of Virtual power and storage capacity of computers, prices machines as means of providing simultaneous, of storing and maintaining data remains high. interactive access to their mainframe computers. Various technologies and solutions have Every VM was an instance of a physical machine developed over time to overcome this problem and provided users with an illusion of direct access and in the end they evolved into virtualization of to the physical machine. It was an elegant and the system for data storage. transparent way of sharing resources and processor I. INTRODUCTION time of very expensive hardware. Every VM was a completely secure and isolated instance of the core Virtual data storage represents a new business system. Users could execute, develop and test model which includes various concepts such as applications without having to worry about virtualization, design of distributed applications and crashing the system. Virtualization was used for IT management which enables a flexible approach decreasing hardware supply costs and improving in application scaling and placement. Virtual data productivity by enabling multi user access on the storage represents a pay per use model which same computers. With the decrease in hardware enables simple and accessible access to computer prices and the appearance of multi-processor resource groups via the internet. On the basic level, operating systems in the 1970s and 1980s, virtual virtual data storage is a simple means of providing machines have almost become extinct. The idea of information technology resources as services. virtualization reemerged in the 1990s with the Virtual data storage includes using networks of appearance of a wide spectrum of PC hardware and remote servers instead of local servers and personal operating systems. The main task of virtual computers for storing, managing and editing data. machines is enabling execution of applications, Locations containing servers which execute designed for different hardware and operating applications and store data are not strictly defined, systems on a certain machine. This trend is present hence the term “in the cloud” is used. End users today.1 access programs via their browsers, whereas the In the computer world, applications and users software is stored on remote servers. Virtual data storage enables efficient resource usage, when perceive a virtual environment the same way they needed only the required amount of resources is do a real one, even though core mechanisms are formally different. Virtual environments often accessed. There is a current trend in the computer industry of developing programs which can be accessed by multiple users without installing anything on their computers. Virtual data storage is also useful if we want to increase the business 1 capacity without investing in new infrastructure, http://www.kernelthread.com/publications/virtualiz training new staff or licensing new software. ation represent false images of machines or resources Public clouds use internet access with hired which have better or worse abilities than physical resources. The complexity of implemented machines or resources. A typical computer system information and communication solutions is hidden uses lots of such technologies. One example is from the user. The majority of management and usage of virtual memory in modern operating system surveillance is done using browsers. Public systems which provides processes with more clouds are maintained by independent service memory than the actual amount of physical providers. Applications from different users are memory the computer provides. It also enables often mixed together on cloud servers, data storage physical memory sharing amongst hundreds of systems and networks. A part of a public cloud can processes. Another example is multitasking where be separated for usage by a single user creating a CPU time is divided which achieves assigning each virtual private data center. The virtual private data task its own virtual processor. center is not limited to distributing images of virtual computers on the public cloud. It also Virtualization is a way of separating programs and provides users with a better insight in its their core components from the hardware which infrastructure. This way, users can manipulate not supports them and presenting a logical or virtual only with images of virtual computers, but also view of these resources. This logical view can with servers, data storage systems, network devices, differ greatly from the physical view. The goal of and network topology. Creating a virtual private virtualization is usually one of the following: higher data center with all components placed at the same levels of efficiency, scalability, reliability, location helps with reducing data locality problems availability, agility and creating a unique domain of because network bandwidth is large and frequently security and management.2 free when connecting elements within the same III.VIRTUALIZATION USAGE MODELS location. The change in business from paper to computers, Hybrid clouds are combinations of public and automation of business processes and the need for private virtualization models. The hybrid model communication with clients caused the need for helps with enabling a system available on request, large numbers of computers and servers. The with the service being provided by a third party. possibility of serving a greater number of systems Only a part of the programs, services and data are on one physical server allows organizations to located in the cloud, while the rest of the IT system become data centers, which eliminates the costs of is located on the company infrastructure. The building one. Computer architects have to take into system structure allows end users undisturbed consideration various issues while changing from access to required data, regardless of the physical the standard model of distributed applications to a location on which they are located and the location cloud based model. There are three basic of the business application which processes them. virtualization usage models: public, private and hybrid clouds. IV.VIRTUAL DATA STORAGE SYSTEM Private clouds are implemented for single user usage and they provide the highest data control, Virtual data storage systems are used to join security and quality. Large companies with their physical storage from various devices in order to own data centers are interested in private clouds create an appearance of a single data storage (also called internal or corporative clouds) which source. Storage servers are computer systems which provide additional optimization using the principle allow general purpose systems safe access via user of virtualization or distributed computing. That way accounts. The operating system of the storage IT sectors become service providers for other server is responsible in deciding which general business sections of the company. The company purpose server is allowed access to which data on owns the infrastructure and has control over the storage devices. If storage servers are connected to execution of applications. The cloud can be general purpose systems via special purpose implemented inside the company data center or in a networks, this configuration is often called Storage remote location. This model enables companies Area Network (SAN). Storage accessed via the control over resource usage, while a third party network is called Network attached storage (NAS), takes care of the required proficiency for regardless whether the general purpose system uses establishing and managing the environment.3 SAN or Local Area Network (LAN).4 Enterprise, Verlag New York, 2005., pp. 12 2 Kusnetzky, D. Virtualization: A Manager’s Guide, O’Reilly Media, Inc., Sebastopol, 2011., pp 1 4 Judith, R.; Davis, Eve, R.; Promotions, w. Data 3 Wolf, C. Virtualization: From the Desktop to the Virtualization: Going Beyond Traditional Data Storage devices are based on rotating media such as they are connected directly to the system. traditional disks, solid state technology such as The local system is unaware of their solid-state disks (SSD) or dynamic memory with location or the type of storage device direct