Virtual server

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A virtual server is a virtual machine (VM) that is running on top of a physical server. The physical server containing the virtual server is commonly called the host whereas each virtual server contained in the host is referred to as a guest. A virtual server is created through hardware virtualization.

Virtual servers are isolated in their own virtual environment allowing multiple instances to be hosted simultaneously on a single server. Guests on the server can run different applications or tasks, on different operating systems, independently from one another. From example, one virtual server can run as a chat server, another as an FTP server, and another as database server, all of which can run concurrently on a single physical machine. To ensure independence and consistency, the physical server utilizes a hypervisor whose role is to monitor the states of each guest. To server users, this appears as if each virtual server is a unique physical device thus maximizing the resources and processing-power of a single physical server. Downtime during server maintenance is also minimized since virtual servers can easily be transferred or migrated from one physical server to another given that both servers are running on the same processor manufacturers.

History

Virtualization was first introduced by IBM in the 1960’s specifically to maximize the computing resources of large mainframe computers. This was done by partitioning mainframe hardware into multiple virtual machines. At the time, a mainframe computer costs millions of US dollars or thousands of US dollars to rent per month, thus, virtualization became an essential technology to efficiently utilize mainframe computers. In addition, this allowed multiple users in businesses and universities to share a single mainframe computer wherein each user has his or her own isolated machine to operate on without affecting another user’s machine.

1960's: IBM System/360 Machines

The concept of virtual machines started with IBM System/360 mainframes running on CP-67 or CP/CMS time-sharing operating systems. CP/CMS was first developed by IBM’s Cambridge Scientific Center (CSC) which consists of a control program (CP), now widely known as a hypervisor, and a console/conversational monitor screen (CMS) which served as a user interface. Each user would have a single CMS and the CP created the virtual machine environment for each user. The introduction of the CP/CMS virtual machine concept allowed:

• Isolation between each user on the machine
  
• Simulation of a full machine for each user on the machine

1970's: IBM System/370 Machines

In 1972, IBM re-implemented CP/CMS and included it as their first virtual machine operating system on their VM/370 or Virtual Machine Facility/370 line of operating systems. At the time, full-support for virtual memory on the hardware side was also introduced on IBM System/370 machines which significantly improved the efficiency and utilization of virtual machine use.

1980's - 1990's: x86 Architecture

X86 architecture first appeared in 1978 when Intel released its 8086 CPU. Upon the onset of x86 processors, the usage of mainframe computers declined since client-server applications, along with Windows and Linux operating systems, made server computing significantly inexpensive. This as well changed the entire IT infrastructure from having large mainframe computers to instead having multiple single-purposed servers. This model, however, presented additional problems:

• Low Infrastructure Utilization – Since servers were single-purposed (i.e. database server, FTP server, web server, etc.), they weren’t being fully utilized as opposed to their counter-parts – the mainframe computer – whose utilization was maximized because of virtualization. An estimate shows that only 10%-15% of its computing resources were being used.
• Increasing Physical Infrastructure Cost – Since organizations needed multiple applications, this meant that they would need a single physical server for each application or task. As the amount of servers increased, the amount of physical space needed to store and manage the servers also increased as well as the energy required to cool and power all of the servers.
• Lack of Disaster Protection – Because of the above issues and associated costs, disaster (i.e. natural causes, hardware corruption, server downtime, etc.) protection wasn’t even addressed.
• High IT Management Cost – Highly trained IT professionals were needed to maintain these systems especially within organizations with large IT sections. This again contributed to the costs necessary to manage these infrastructures.

1999: VMWare Introduces Virtualization on x86 Sytems

Because of the aforementioned problems, virtualization was revisited as a possible solution by some organizations and in 1999, VMWare introduced virtualization on x86 systems. Because x86 systems had absolutely no support for virtualization, this innovation baffled many experts since the virtualization on these systems was deemed impossible. Ever since this introduction, server utilization significantly increased from ~10%-15% to ~60%-80%, in addition, the physical need for storage and maintenance was reduced 5-15 times. These figures alone show that not only is there potential for growth in the market, there is desire for enterprises to begin using these virtual servers. Financial estimates put this market's value at over $19 billion dollars.

Why Virtual?

If there is all this growth in this industry, what's the reason behind it? In a word, money. In moving to virtual servers and utilizing virtual servers, Business Insights reports that there are several places that costs can be cut:

• Physical machine costs - For an enterprise running 250 dual-core servers could save over three million dollars over a three year period. Additionally, each enterprise could save close to $125,000 per 1,000 PCs per year in power saving costs by moving to a server-hosted desktop virtualization solution.
• Power costs - Although the move to virtual servers often requires the purchase of new hardware, over the long term IBM research quotes that the server space could be reduced by up to 90%. Fewer servers equates to less money being spent on power and cooling.
• IT department costs - Beyond the physical costs of purchasing and powering physical servers, the largest cost associated in an IT department is labor. Although running virtual servers would require a more specialized IT crew, it will require a smaller staff which is critical for companies that are looking to become leaner as 70% of costs are spent on labor.
• Line of Business Users - Since the virtual server farm is smaller and easier to maintain, then the availability of services is more likely to be guaranteed and support and can be provided quicker, the productivity of these LOB users will be increased.

Corporate Landscape

The current corporate market for creating virtual servers is volatile and involves a few main players.

Major Players

• VMware - The current leader in the virtual server market. In 2007 VMware represented over half of the market for x86 servers and over 80% of large corporate enterprises. Their main products are:
  • VMware Infrastrucre - Used to create and manage virtual server environments
  • VMware virtual Center - Used for monitoring
  • VMware Lab Manager - Used to create test environments
  • VMware Server - Server partitioner
  • VMware Converter - Used to convert physical servers to virtual servers
• Microsoft - Microsoft first tried to enter the virtual server market in 2002 but was relatively unsuccessful because purchasers were uneasy about the alternate OS on Microsoft's offering. In 2006 Microsoft launched Virtual Server Manager touting that it could do everything VMware's virtual servers could. Though a bit of a reach, they did release a virtual server for free that would also support a Linux based OS which worked to calm the uneasiness felt in 2002. It's main product is:
  • Microsoft Windows Server Hyper-V - Not quite as robust as VMware, but it is a direct challenge.
• Citrix / XenSource - Citrix leads the desktop virtualization market with 19% of that particular market. It also purchased XenSource in 2007 and is focused on virtualization processes using entirely open source coding. Citrix works closely with Microsoft in developing virtual applications. Its main products are:
  • XenExpress - Virtualization starter package
  • XenServer - Virtualization platform for Windows and Linux servers
  • XenEnterprise - Enterprise-wide virtual management tool

These three companies make up the vast majority of the virtual server market and have such a lead that the market landscape should not drastically change in the next several years.

Challenges to Growth

There are several challenges this industry faces if it is to continue its fast growth:

1. Security - According to one report, 60% of virtual servers are less secure then the physical machines they replaced. With advances in technologies, that number is sure to decline and is estimated that it should drop to 30%. However, for many enterprises with especially sensitive data and processes it needs to protect, that level of security may be a limiting factor to switching to virtual servers despite the cost advantages to doing so.
2. Licensing - This is a challenging situation where the software vendor is still working under the physical server model when the hardware has evolved to virtual servers. In the physical server model an enterprise would need to purchase one license for each machine that needed the piece of software. However in the virtual server world, each machine might have dozens of instances of the same piece of software running on it requiring dozens of licenses to be purchased. This immediately eats away at the money saved from using fewer physical servers.
   However it appears software manufactures are starting to change their pricing structure. Microsoft, for example, will allow that its dual core machines will only need one license for their products and that certain customers that have purchased specific versions of the Windows operating system will be able to run up to four copies of that OS on the desktop. However, for large scale enterprises this is a hefty cost that makes the cost/benefit analysis for upgrading to virtual servers difficult to run.
3. Software - In addition to licensing concerns with virtual software, there is the fact that not all software is able to be virtualized for various technical reasons. Internet Explorer, for instance, is extremely difficult to virtualize. As enterprises begin to use more and more virtual servers, balancing applications that cannot be run virtually and those that cannot is a challenge.
4. IT Technicians - The change to virtual servers requires the IT staff that maintains them to be much more skilled and knowledgeable. Not only is that individual responsible for the hardware that he or she was responsible for before, they must also have the necessary skill set to be able to service a wider array of software that might be found on a virtual machine. For example on host server might be running instances of Windows and Linux. In the past, that would require at least two servers each with potentially their own technician. As it is not feasible to hire a person for each instance of a different operating system, the enterprise must hire more skilled IT staff.

Although these are all difficult challenges to consider, the analysis of the market conditions suggests that these aren't conditions that act as a barrier to entry.

In Popular Culture

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