Virtualization FAQs

What is a virtual machine?
Each isolated server environment functioning as an independent entity while sharing the physical server with other entities, each of which can be running different OSs and/or applications. For example, the subtracted Windows and Linux servers utilizing the same single blade server in the physical world would be labeled as virtual machines.

How does virtualization work?
Server virtualization solutions partition the physical server into isolated regions using thin layers over the physical server. Therefore, the isolation of each defined region causes it to act as an independent entity--preventing application problems in one region from affecting the environment of another region that can be using a different OS or running a different application--even though all regions with varied OSs and/or applications share the same physical resource.

What are the advantages of virtualization?
The advantages of a properly planned and implemented virtualization project are extraordinary. For example:

• Server consolidation: Often the most popular advantage of virtualization. It essentially reduces unused capacity of multiple servers by letting the user transplant multiple applications with different OS needs onto a single server separated by thin layers to allow each partitioned layer to run independent OSs for different applications. Therefore, instead of having 3 servers, each using 20 percent capacity, there can be only 1 server using 60 percent capacity. Infotech, the leading IT research firm, estimates that with virtualized servers optimizing overall capacity and replacing distributed servers, companies can boost hardware utilization to around 60 to 80 percent. Some companies have even achieved consolidation ratios of 12:1.
• Smaller footprint: With virtualized machines optimizing each physical server, companies will have fewer server boxes on site, which cuts electrical and utility bills and maximizes cost per square foot of land used for the data center.
• Hardware costs: With fewer physical servers required to accommodate the same project burdens, companies save money on hardware purchasing and maintenance.
• Flexibility and agility: With increased agility and flexibility in quickly synthesizing different operating system environments, virtualization allow users to easily run legacy applications on the same physical server as the latest versions. In practice, this means less time lost in application migration and greater ability in restoring systems in post-disaster scenarios.
• Ease of Testing and Development: Having the ability to quickly changing operating system environments, without destabilizing servers allows designers faster development cycles. It also gives them the ability to test new applications in different virtual environments without needing additional hardware resources.

What are the issues to watch out for?

• Software costs/licensing: Virtualization provides unparalleled advantages in running different OSs for different applications to reconcile even legacy issues with ease. But one of the most important issues to keep in mind is that software licenses for each isolated environment are required. This may be a near moot issue in open source software, only having to be careful of server sprawl; however for licensed products, this can cause high license fees.
• Capacity planning: Matching hardware capabilities with server needs is critical in optimizing the broad array of benefits from virtualization. Therefore, while keeping performance paramount, it is vital to enjoin the greatest number of virtual servers onto a single physical server.
• Training: Businesses should budget for time and money for training when planning for virtualization of their distributed servers, as they would for any IT project upgrade.
• Management: To assume that physical box reduction is proportionate to cuts in the IT staff is a detrimental mistake. Although virtualizing machines may take less physical maintenance, they still require management to properly realize their profit potential.
• High consolidation expectations: The consolidation ratio is unique for every project and is dependent on the power of your current physical boxes verses the resource demand of your existing applications. If your current physical servers are averaging low capacity usage, then consolidating with virtualization will certainly boost efficiency. But, weak server boxes working at capacity to serve the needs of numerous powerful applications will not yield the same benefits.
• Upfront hardware investment: To fully realize the benefits of virtualization, companies will need to evaluate the trade-off between the costs of buying new hardware against the pitfalls of virtualizing on less powerful hardware. Basically, virtual machines should be located on processors with sufficient power to manage the tasks asked of them.
• Legacy support systems: When a single physical server is hosting numerous virtual machines, many older support systems need to make security adaptations. For example, some firewalls may still assume that only one IP address can originate from a specified piece of equipment.