The Challenges and Pitfalls of Virtualization

By Sanjay Srivastava
Updated: September 06, 2012

The Challenges and Pitfalls of Virtualization

Server Virtualization is an extremely popular technology for managing computing resources more efficiently and getting the most out of every computing cycle. The times when each server was used to run a single application is a thing of the past and IT administrators are delivering much better capabilities via virtualization than they were earlier capable of doing.

If you have your own business and have not yet virtualized themyour servers, then chances are that you use multiple servers for various preset tasks and operations within your workflow. In most traditional IT setups, servers are normally used to 10% - 20% of their capacity. The remaining computing capability will lie idle. While some of this is planned to deal with scaling to meet capacity, that need is no longer so strong because virtualization will let you return the capacity if there is an unexpected demand. Once that is understood, not using the capacity is a total waste and adds to the cost of the IT setup without any significant contribution. It also means that your maintenance and running costs are higher than they need to be.

Server virtualization is a mandatory prerequisite for Cloud Computing and it also shares a lot of its benefits including:
• Enhanced utilization of resources
• Better availability for company applications
• Lower maintenance costs
• Lesser personnel needed for the IT department

Virtualization involves the use of a new software layer on top of the traditional server. This layer supports a number of different virtual servers, each with its own operating system and applications. Naturally, the utilization of the server increases and this increases the return on the investment you have made to procure and support the server. However, before implementing server virtualization there are some key aspects that any entrepreneur or IT administrator needs to keep in mind. Here is a list of challenges and the pitfalls that may be experienced when setting up server virtualization.


Assuring Compatibility and Efficiency

When it comes to Server Virtualization, one of the biggest obstacles that needs to be overcome is preparing a robust infrastructure and making sure that all its underlying components such as CPU, Storage Devices, Operating Systems, Network etc. are compatible, efficient and will provide sufficient performance without affecting the workflow.

Making sure that all these are in place may take a lot of time and may require special skills. It also depends on how modern your equipment is.  If you do not have the skills readily available in-house, you may need to acquire these or engage a consultant beforehand and establish a preset list of mandatory changes and improvements in order to assure a smooth virtualization process.

The Network

Virtualizing servers before making sure that the network infrastructure can handle it is a risky undertaking. After the process is complete the network will be under a lot more strain and making sure that it has what it takes to sustain the added traffic is critical.  Once the virtualization process is complete and problems arise, it will be very difficult to tell whether the performance issues are linked to network issues or at the server end.

Computational and storage capacity

Besides obvious differences, virtual machines also generate I/O requests at an increased frequency and since virtualization means creating more servers, discs may have trouble keeping up with the increased workload.

It is not uncommon to realize that some applications are actually slower when run through virtualized machines even if memory management techniques like page sharing are in place and being used.  This is because larger blocks of data have increased priority which means that smaller I/O requests have to wait before being processed. A viable solution for this kind of issues is workload analysis before the virtualization so that you are able to estimate approximate future hardware and network usage and prepare accordingly.


While Server Virtualization comes with a reduced maintenance process and lower costs, it also requires an enhanced set of skills from the personnel working in the IT department. This can give rise to major problems and you may need to hire manpower with these skills.

What we are talking about here is a complex computing environment where all the parts are interconnected and to some degree also interdependent. This is why there is a higher need for individuals that possess a more varied skill set. If this requirement isn't met prior to the virtualization process, the IT department may need some personnel training or the services of an IT consulting firm.


Mismatching Servers

This aspect is commonly overlooked especially by smaller companies that don't invest sufficient funds in their IT infrastructure and prefer to build it from several bits and pieces. This usually leads to simultaneous virtualization of servers that come with different chip technology (AMD and Intel).

Frequently, migration of virtual machines between them won't be possible and server restarts will be the only solution. This is a major hindrance and actually means losing the benefits of live migration and virtualization.

Creating Too many Virtual Machines per Server

One of the great things about virtual machines is that they can be easily created and migrated from server to server according to needs. However, this can also create problems sometimes because IT staff members may get carried away and deploy more Virtual Machines than a server can handle.

This will actually lead to a loss of performance that can be quite difficult to spot. A practical way to work around this is to have some policies in place regarding VM limitations and to make sure that the employees adhere to them.

Misplacing Applications

A virtualized infrastructure is a more complex than a traditional one and with a number of applications deployed, losing track of applications is a distinct possibility. Within a physical server infrastructure keeping track of all the apps and the machines running them isn’t a difficult task. However, once you add a significant number of virtual machines to the equation, things can get messy and App patching, software licensing and updating can turn into painfully long processes.

In Summary

Server virtualization can bring major benefits to your organization. However, depending on the vintage and type of your existing equipment there could be major expenses involved. If you do not have the skills in-house, you may need to obtain skilled consultancy support to ensure that you take all the necessary steps and do not make mistakes that could hurt your business.  There are several challenges and pitfalls to watch out for and anticipating these and being well prepared will help you get the best out of your new initiatives.

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