The buzz around data centers in the last few years has centered on virtualization -- virtual servers saving real space, reducing real heat -- and easing the costs of real hardware expenditures. That is enough to make IT managers pay attention. However, it can lead you right back to an environment full of increased complexity defeating the purpose of deploying virtualization in the first place. Learning how to manage the virtual environment requires some investigation.

Before spending the money on products and heading full-speed-ahead with installation and training, a business case should be developed. Any purchase should fit within the existing data center infrastructure strategy, and the strategy should align with the company’s business goals. If explored properly, making a business case for adopting virtualization in the data center can show the benefits far outweigh the cost. 

Server virtualization can be applied to business objectives in many ways, such as in the reduction of operational and capital expenses by enabling greater use of physical resources. Specific benefits might include the promise of improvement in all theses areas:

• Disaster recovery.  Improved operational efficiency. Mission critical servers and applications must be restored quickly to keep the business operating. Backing up and restoring virtual machines involves no installation or configuration of operating systems or applications and therefore can be done more rapidly than restoring a physical server.  Additionally, disaster recovery testing can be performed much more quickly than it can in a purely physical environment.

• Power and Cooling. Reduces operational expenditures. Fewer physical servers will result in lower power and cooling costs. 

• Server Consolidation. Reduces capital expenditures. Fewer physical servers take up less space reducing the amount of floor space needed to house servers and results in less equipment to maintain. There is also a reduction in licensing cost for operating systems.

• On-demand Computing. Improved service levels. Engineers can request and receive a virtual machine for a test or project usually in the same day instead of waiting weeks or months for enough server space for the project.

• Faster Provisioning. Reduces operational expenditures. Adding or replacing servers, such as when retiring legacy systems, is conducted in a shorter amount of time.

However, it is not just about reducing the number of servers. Manpower, licensing, maintenance, operations, and facilities -- all of these items need to be considered.  When trying to determine how much server consolidation a data center can handle, audit the server loads for normal and peak utilization items.  Most servers are operated at well under 50-percent utilization, and an audit along with information about cost savings and all the benefits add up to a proposal that will allow a virtualization implementation project to move ahead.

Before investing in a virtualized environment, though, it is critical that one understand the management issues that will undoubtedly arise from a mixed physical-virtual environment. Approaching it with separate tools and staff will have IT essentially running two separate data centers, which, in addition to being inefficient, can create inconsistencies and serious missteps.

These new management challenges occur because of two main reasons:

• Virtual servers by their very nature must be managed differently from physical servers
• Data centers are only partially virtualized. That is, some servers are physical machines and others are virtual machines residing on physical machines with other virtual servers.

To reduce complexity IT organizations must re-think the way they manage their increasingly dynamic mix of virtual and physical servers.

Virtual Server Technology Challenges

While virtual server technology can help IT organizations significantly improve the economics of data center infrastructure, virtualization also introduces new complexities and challenges when it comes to managing that infrastructure. Some of these challenges arise from the nature of virtual server technology itself. Some arise from the fact that virtual servers must be managed in conjunction with all the servers in the data center that remain “unvirtualized.” Together, these two sets of challenges significantly impact the way IT organizations must operate.

In a recent survey of 299 IT and data center professionals conducted by Actionable Research (April 2008) on behalf of Avocent, the findings were less than encouraging for virtualization. While respondents said they had begun to move toward server virtualization, mainly for its cost reductions and energy savings promised -- they also revealed that the technology offered unique challenges.

A majority of respondents have rolled out some level of server virtualization, but, of those respondents, 24 percent had experienced a disappearance of a virtual server from their system and in fact, 18 percent had permanently lost a virtual server!

The top reason for deploying virtual servers in the first place, was for cost savings. Of those polled, 32 percent stated they initially looked to virtualization as a means of decreasing hardware costs. Their responses, however, showed two key continuing concerns related to managing server virtualization:

• 45 percent said they had concerns about the lack of expertise that IT personnel had with virtualization.
• 44 percent said they were concerned that virtual servers could fail from a component failure in a single physical server.

To be sure, for many applications -- especially high input/output ones like e-mail -- virtualization is neither practical nor advisable. No data center can, therefore, ever be fully “virtualized.”  It is far more accurate to discuss “partial virtualization” or “limited virtualization” when the topic of virtualization comes up it. IT organizations will always have to deal with a mix of physical and virtual server resources. Investments in physical servers are costly, and IT departments will not scrap those legacy investments anytime soon. IT organizations are still figuring out how and when to implement virtualization, and adoption rates can depend on many non-technical factors, such as competition for IT budget and whether the department can deliver the appropriate support for virtualization.

Challenges that arise from the nature of virtual server technology itself include:

• Giving specific IT staff appropriate privileges for specific virtual machines. It can already be somewhat complicated to give IT staff access and appropriate operational privileges for specific physical servers. When multiple virtual servers are running on individual physical machines, the administration of these rights becomes even more complex. 
• Maintaining management assignments as virtual servers move from one physical machine to another. To avoid giving systems administrators and application specialists access to VirtualCenter (because of potential inappropriate control over the data center’s virtual infrastructure), IT organizations use a manual approach for the distribution of IP addresses and/or management URLs to the specific virtual machines for which each IT employee is responsible. 
• Accessing multiple virtual servers connected to different Virtual Centers. At this time, VMware doesn’t enable IT staff to unify their views of multiple virtual servers residing on different physical machines, if the ESX Service Consoles of those different physical machines are connected to different VirtualCenters.
• Protecting many virtual servers from component failure in a single physical server. With physical servers, there is a one-to-one relationship between component failure and application outage. When multiple applications are running on that same server, the stakes go up. IT organizations implementing virtualization have to be particularly sensitive about the vulnerabilities created by multiplexing large numbers of virtual servers onto a single physical machine – and must be sure they have the out-of-band access to those physical machines necessary to address BIOS- and hardware-level issues.

• Exclusive use of Microsoft Active Directory. VMware uses Microsoft Active Directory exclusively to administer management rights and permissions. This can potentially be problematic for IT organizations that need to drive management access using technologies such as LDAP, RADIUS and single sign-on in order to support their broader infrastructure management architecture.

The above-mentioned challenges are some of the initial management obstacles that early adopters of VMware and other virtualization solutions are discovering as they roll out virtual servers in their data centers. There are likely to be others. The point is that the emerging “virtualized” data center is even more complex to manage than conventional environments -- and that at this time VMware’s native management tools are insufficient for addressing this complexity.

It is difficult to fully understand how virtualization will impact management operations, so before you implement, it is critical to look for a solution that can:

• Access virtual and physical servers from a single interface
• Access virtual servers distributed across multiple VMware VirtualCenters from a single interface
• Consolidate events and alerts from both physical and virtual servers
• Granularly control access rights to both virtual and physical servers in a common manner
• Maintain management assignments for virtual servers even as they are moved from one physical machine to another
• Granularly audit management operations performed on both virtual and physical servers

IT organizations are under increasing pressure to do more with existing resources, or with even less. Budgets are rarely increased proportionally to escalating demands. The appeal of virtualized machines is understandable. IT departments gain immediate deployment, more dynamic allocation of server capacity and more mileage out of hardware investments by running multiple virtual servers on a single physical machine.

These benefits are attractive for businesses that need to adapt to market changes more quickly to take advantage of growth opportunities.  But, as appealing as virtualization may be as a solution to saving time and money, organizations must have the business plan in order and proceed with caution – replacing traditional servers where it makes the most sense – and training staff to manage those complex new environments. Data centers are really only partially virtualized. That is, some servers are physical machines and others are virtual machines residing on physical machines with other virtual servers. To reduce complexity IT organizations are wise to rethink the way they manage their increasingly dynamic mix of virtual and physical servers.

Ben Grimes is the chief technology officer for Avocent.