Introduction
Server virtualization is a technique of organizing several separate virtual machines on one physical system. These virtual machines can be thought of as virtual private servers that hide the physical servers, operating systems, and other network resources from people using the servers. By implementing several virtual machines, various operating systems can work simultaneously on a single hardware platform managed by the server administrator (Microsoft). The server administrator operates a software program that helps in the separation of the hardware into several logical environments. Since managers and business organizations have not fully realized the strategic benefit of hardware and computing power investments, it is now appropriate, for instance, to make one dual-core server into as many as 16 logical servers that operate different virtual operating systems. This results in major savings in hardware costs and maintenance costs. Therefore, this report analyses the concept of server virtualization in relation to virtualisation models, impacts of server virtualisation, the use of virtualisation, and licensing and support considerations.
Models of Server Virtualisation
According to TechTarget, the famous models of server virtualisation are the virtual machine technique, the paravirtual machine technique, and operating system layer virtualisation (1). The virtual machine model uses a host and guest standard. Every guest operates on a virtual copy of the hardware component and thus the operating system works with no alterations. This model allows the network administrator to categorize guests with dissimilar operating systems. The guest is concealed from the actual operating system and server hardware components, which are transparent. However, actual operating resources are provided by a hypervisor program, which synchronizes instructions to the processor. The coordinating program is termed a Virtual Machine Monitor (VMM). Thus, programs like VMware and MS Virtual Server implement this model.
The paravirtual machine (PVM) technique implements the same standard as the VM model together with a VMM. The main difference is that the VMM in this model restructures the code of the guest operating system under a technique called porting. Using porting, the VMM efficiently uses the system calls to coordinate the guests according to their priorities. Thus, paravirtual machines can also operate several operating systems. The main examples of systems that implement this model are Xen and UML.
At the OS level, virtualisation is realized through having one OS kernel that distributes functionality to every guest component. The guest machines operate the same OS as the host machine. This is deemed as a distributed OS which reduces process interactions and processor overhead. It is also appropriate that each distribution remains separate from its neighbor in order to enhance fault tolerance. Thus, the OS level model can maintain many guests concurrently as compared to other models. The main examples of systems using this technique are Vituozzo and Solaris Zones.
Impacts of Server Virtualisation
Many organizations are implementing server virtualisation because of the advantages expected from such a technique. Virtualisation enables a company to reduce capital on hardware and software and hence cut operational costs to improve the fundamental business processes. As organisations embrace server virtualisation, there is a need to critically evaluate the benefits and some problems associated with it.
Looking at the advantages of server virtualisation, various beneficial effects can be realized. First, server virtualisation saves costs of hardware and software. A company will only need to purchase single server resources and share the components among other virtual servers. It is considered to be cost-effective because having multiple servers with different hardware platforms is more expensive (Posey). For instance, ISPs implement virtualisation to distribute a single server to many customers in a transparent way. Second, server virtualisation enhances collaboration and development. People can work on a development project and thus through centralized management, collaborative work can be distributed and managed in the various virtual servers without altering the essence of coding done. Third, there is enhanced performance and utilization. With only one server administrator, the IT resources are utilized and the management ensures that all the guest servers are integrated into the coordination process hence easier management. Fourth, this technique combines physical IT resources, such as hardware, software, people, and procedures. Having centralized management enables an organization to effectively deploy servers and storage to various users.
Another important advantage of virtualization is that companies can improve their business flexibility. By cutting down the number of physical servers, enterprises are able to concentrate on improving their business applications and data types. This also saves costs and ensures that downtime from systems is catered for as in the case of virtualization at the OS layer (Biggar).
However, there are several disadvantages attributed to server virtualisation. First, virtualization demands new storage. As demands for servers in an organization increases, there is also an increased necessity for a storage environment since lots of data capacities need to be handled from various system calls. For example, when organizations try to implement new systems to cater to application requirements for more space and throughput, it is likely that storage sprawl can emerge. Thus, there is a need for good storage architectures that can be able to address the scaling requirements of virtualization (Biggar). Second, virtualization results in security challenges. Since the aim of virtualised services is to keep resources separate, it may be possible that in some cases the hidden servers are accessed without authorization. The management is tasked with the duty of ensuring that the system is secure and operating efficiently; this is a difficult task in case of multiple accesses. However, the contemporary virtualization solutions came with security policies that help administrators to monitor the network under on control platform.
Using Server Virtualisation
Implementing server virtualisation is efficient for small-scale applications that are used for minimal operations. George Ou suggests that this technique should not be incorporated in programs that are required to achieve high throughput and turnaround times (1). In this case, for applications that require more than one server to meet the organizational performance, having server virtualisation can reduce the performance in the long run. Subdividing the processing power of a server, for instance, 12 GHz into 16 750 MHz servers, would mean that in cases where there is the susceptibility of failures or idleness of servers, the processing power at the disposal of the remaining servers will be small. Hence, high-performance applications should not be implemented in a virtualisation environment.
In most cases, high processor utilization counts are considered as a factor in high hardware usage. However, in cases where there are many requests for applications, the CPU utilization numbers should not be entirely used as a high-performance indicator. Likewise, a general policy is that a server should never go beyond 50% processor utilization in peak hours and it is appropriate that the responsiveness of applications should not go beyond the sensible Service Level Agreement (SLA). Thus, CPU utilization should not be the only factor that determines an efficient server virtualisation strategy, but also input/output (I/O) utilization in relation to the storage and network performance. For servers that require a lot of hardware for performance purposes, it would be appropriate to maintain them without much CPU consideration even though processor requirements can be fulfilled in the virtual settings (George Ou). Besides, there are virtualisation solutions that can perform physical to virtual server transition through making copies of physical servers’ drives and creating virtual images with required configurations for virtualisation.
Licensing and Support Consideration
A major issue in server virtualisation is the licensing of the virtualisation product. Many organizations fear buying the license for every virtual server since the cost of licensing software is normally higher than the cost of hardware, thus it would be unreasonable to operate a $25,000 software authorization on a virtual server that uses a shared computer. In such cases, it is appropriate to use the license on the most powerful physical server without distributing the server capabilities. For instance, Windows Server 2003 Standard Edition requires payment for every virtual server running in the virtualization environment. However, Enterprise Edition of the same version enables the server administrator to run a single license on four virtual machines. Thus, large organizations are deemed to pay more than small enterprises while deploying virtual servers (Posey).
Consequently, the cost for a virtualization license in open source software is normally free. However, the major consideration is the support facilities for the software. It is, therefore, appropriate to consider the operational costs while opting for open-source software. In essence, when evaluating server virtualisation costs, it is important to consider licensing and the overall efficiency of virtual infrastructure.
Conclusion
Server virtualisation is an IT solution that helps an organization to logically divide a single server’s capability into many virtual servers. This is a style that incorporates storage virtualisation, network virtualisation, and autonomic computing. This paper has discussed server virtualisation in various aspects. The major models of virtualisation discussed are the VM model, paravirtual machine, and OS layer virtualisation. All these models distribute the physical server into virtual machines, with OS layer virtualisation using a system-wide OS for managing virtual servers. The merits of server virtualisation are a combination of physical IT resources, easier management, cost reduction, and efficient use of servers and storage. However, problems may arise in regard to storage demands and security breaches due to centralized management. Therefore, for smaller organizations using lightweight applications, virtualisation is cost-effective as compared to large organizations requiring many servers and high-performance applications.
Works Cited
Biggar, Heidi. “How Server Virtualization Impacts Storage.” Data Centre Knowledge. 2010. Web.
George, Ou. “Introduction to Server Virtualization.” TechRepublic. 2006. Web.
Microsoft. “Server Virtualization.” Virtualization Products and Technologies. 2009. Web.
Posey, Brien. “The pros and cons of Server Virtualization.” TechRepublic. 2003. Web.
TechTarget. Server Virtualization. 2009. Web.