Using Virtualization to Maximize Centralized Computing Data Center Resources

Moving to a virtualized environment can improve the efficiency of your IT infrastructure. We explain how to determine the best configuration for your environment.

by Jeff Jilg, Ph.D

Moving to a virtualized environment can certainly help increase the efficiency of your existing IT infrastructure. Many companies are turning to virtualization as they evaluate an upgrade of aging computer desktops. Virtualized desktop infrastructure (VDI) provides a model that reduces maintenance burdens and centralizes computing resources into the data center. Ultimately, this model enables users to enjoy the same compute power and application access while maximizing the IT investment in software and hardware to support end users.

The overall objective of evaluating virtualized environments is to determine the best configuration and fit for your environment so you can maximize the technology.


Virtualization can leverage hardware resource utilization more effectively. However, most PCs have less than 10 percent performance utilization. End users can be in meetings, on the phone, or accessing the PC with typical office software which does not tax the PC heavily. In these cases, the PC is idle or is not being fully utilized.

Before deploying virtualization a general performance characterization of the typical user should be made. While there are no formal benchmarks available, one can estimate PC utilization and perform pilot VDI deployment using a small users:PC ratio. Alternatively a performance script can be developed to emulate a standard user’s PC utilization—using applications that are used in the target environment. From the resulting measured performance, an estimated user:PC ratio can be established for the pilot density virtualization rollout.

Once a comfortable user experience is established at a low user:PC density ratio, more users can be assigned to each virtualized PC over time. In addition to hourly usage patterns, include reboot time in the evaluation. For example, if your virtualized environment has power fluctuations or maintenance during the work week, you would not want your users to wait 30 minutes or longer for a virtualized PC to boot up. In general, a virtualized PC which has a large number of users configured will take longer to reboot than the reboot time for a virtualized PC which has fewer users configured. As a consequence, it may be possible to establish a high user:PC ratio on the virtualized PC from a user-interaction standpoint, but if reboots are common, then the ratio should be lowered to enable a higher uptime percentage. Users get cranky when they can’t log onto their PCs.


One of the natural consequences of moving compute resources into the data center is increased manageability. IT resources are effective when problems are readily accessible. In some cases it is possible that reduced IT resources are needed to maintain the same number of users when compared to desktop PC deployments. Consider the physical deployment of the hardware. In a desktop PC deployment, the PC must be installed, configured, and maintained at users’ desktops. In a virtualized environment, most of this work is done in the data center—so it is easier to accomplish multiple installs and problem debugging in one physical location. The deployment of thin clients for virtualization support is much easier than configuring a PC at a desktop.

One method of reducing deployment time is to develop a set of standard VDI images. Each image contains the operating system, applications, and associated configured environment for a typical user. A VDI image can be deployed to an existing virtualized PC in the data center in minutes by simply configuring the virtualization environment and copying the image to the target virtualized PC. A checklist can be developed to perform configuration of the final end user. Deploying users in this fashion can literally reduce new-user rollout time to minutes, where the bulk of the deployment time is the 10-minute, desktop, thin-client hookup.

Virtualized environments require a more complicated configuration than does a standard desktop deployment. IT resources will need more training to understand and plan for virtualization environment installations and maintenance. Initial rollout requires a ramp-up of additional configuration planning that is not encountered on desktop rollouts. Similar to desktop deployments, VDI rollouts are scaleable. Once a plan for 50-100 users is developed, most of the configuration for that environment can be scaled out proportionally. Some items (such as networking and Active Directory configuration) will be similar—so there is not a significant difference with either environment that requires additional training.


Another benefit of virtualization is the centralization of data into the data center. This reduces the IT resources needed to physically lock down data which is located outside the data center. Most companies have some data which is confidential and/or contains data about their clients. Since thin clients don’t have a hard disk, there is no concern that hard disks can be stolen.

Thin clients at the desktop often have USB ports, and these can typically be disabled in the configuration settings. This effectively reduces the chance that data can be removed from the data center since the disabled configuration prevents users from using USB devices to copy data.

Backups and Disk Usage

Hard disk location and configuration for virtualization enables development of easy backup strategies. It is not necessary to establish the users’ disk space on the virtualized PC, and it is often easier to setup the VDI disk space on an external NAS or SAN networked drive. This has the advantage of being scaleable – since the disk space allocated to a user can be expanded as needed. Also the networked disk shares are easy to access for backups.

If a networked share configuration is compared to a standard desktop with a fixed hard drive, consider that most users do not fully utilize the local desktop PC hard drive. Additionally, it is more challenging to establish backups on the local desktop PC hard drive. Some users may turn off their PCs at the end of the day—which makes backups even more challenging. The networked-drive space configuration advantages outweigh local hard disks in one other aspect. If a hard disk has errors, it is easier to swap out the disk in the data center and restore data from the backup from that one location. Again, physical asset centralization provides a more convenient and efficient path to establishing the initial configuration and to performing maintenance on a VDI client.

Maximized Resources Reduce Costs

Multiple factors contribute to reducing costs in a virtualized environment. Density enables more efficient hardware exploitation. VDI provides a more manageable and secure solution which reduces the IT resources required. Backups and disk usage become more efficient because of the inherent networked file shares that most VDI environments utilize. The overall equation with virtualization is a more efficient system with an end benefit to the overall cost structure to deploy the solution when compared to typical desktop PC deployments.

- - -

Jeff Jilg, Ph.D. is the director of technology services at ClearCube Technologies. You can write the author at