Virtualization - Defined
Virtualization can be divided into three separate categories, each of which has specific ideal use cases.
Server Virtualization is an effective technology used by the University Data Center and the ATLC Communications Center to provide complete virtual servers which mimic all the functions and features of a physical server, but can be built, deployed, and modified quickly using sophisticated virtualization software such as VMWare™ or Hyper-V™. Server virtualization is a technology typically only deployed in large data centers, and as such is not within the scope of this information brief.
Desktop Virtualization is similar to Server Virtualization, except that instead of virtualizing a physical server, a complete desktop operating system such as Windows is delivered, typically via video streaming to a standard desktop, laptop, thin client, or mobile device. In an optimal Desktop Virtualization scenario, a user is provided a complete Windows desktop environment, with all required applications pre-installed and ready, and the user's preferences and profile information is saved across multiple sessions.
Application Virtualization is used when only a selected set of applications are provided to the end user, as opposed to a complete desktop plus applications. For Application Virtualization scenarios, the end user is expected to have a suitably-powerful desktop or laptop, whereas, in the Desktop Virtualized scenarios, the end user may only need a minimal or “thin” client.
Virtualization is the key technology that is enabling so-called “cloud” services. A cloud services provider is best positioned to exploit virtualization technology to deliver cloud services to business and users.
Application and Desktop Virtualization – Issues and Strategies
Software virtualization has become a popular strategy among TTU departments. While virtualization technology has some real benefits for certain use cases, it carries with it complicating factors and issues such as software licensing restrictions, the need for high-end server infrastructure, extended technical support on a 24x7 basis, and other hidden costs. These factors and issues are often overlooked during the planning and implementation of virtualization projects, resulting in expensive investments in IT infrastructure and staff that do not deliver the expect results and benefits.
The IT Division is providing this information brief in order to increase the awareness and understanding of these issues, and to assist University colleges and departments to more effectively assess the costs and benefits of virtualization.
The following lists summarize the benefits as well as the often overlooked issues of application and desktop virtualization. All of the benefits have counter-balancing factors and issues that must be considered. For a more detailed narrative, see the section of this brief entitled “Virtualization Use Cases and Complicating Issues”
Desktop and Application Virtualization Benefits
- Can enable a Bring Your Own Device (BYOD) strategy for faculty, staff, and students
- Can displace physical computing labs with a virtual lab
- Can provide secure remote access to protected IT resources and services
- Can provide a more uniform and consistent experience for the end user
- Can extend the normal 3-5 desktop lifecycle replacement
Factors and Issues
- Licensing costs for the virtualization software are considerable and varied among virtualization vendors
- Some third party software vendors restrict, charge additional fees, or do not allow their software to be virtualized
- Some software is not compatible or does not function adequately in virtualized environments
- There are significant backend server, storage, software, and backup infrastructure costs that must be adequately sized, supported, and refreshed
- The backend infrastructure requires highly skilled and trained technical staff
- Virtualization projects often require additional consulting services by the vendor and/or their partners during implementation
- A virtualized environment requires additional end user support, including supporting those users beyond normal working hours, that areas may not be staffed to provide
- Virtualization does not provide an overall cost savings
- Depending on the virtualization vendor, there are varying license costs for each virtual client. This is a new cost that must be factored in when planning a virtualization project
- Some software vendors only allow use of their software in virtualized environments under restricted conditions or with additional licensing fees
Some software does not function properly in a virtual environment. Examples including graphical intensive software, such as CAD tools, audio/video editing, and older software that is no longer being maintained by the original vendor
- Significant investments in backend server and storage infrastructure
- Virtual desktops and applications require sophisticated high end server infrastructure, since most of the computer processing that would have been performed on the end user's computer is being shifted to the servers in the data center
- The backend server infrastructure supporting the virtualized environment must be robust enough to provide the performance expected by the end users, particularly in peak demand periods. A solution built to attempt to lower operating cost may do so at the expense of end user performance and satisfaction
- Certain applications are very resource (CPU and/or storage) intensive. Virtualized applications such as SAS™ statistical software or Database Management Software, such as SQL Server, have been problematic for the backend infrastructure and support staff when end users create run away jobs or database queries that monopolize all of the server's CPU and/or storage. The same scenarios in a non-virtualized environment only impact the particular users who initiate the jobs or queries, whereas in the virtual environment, a few users can create performance issues for the entire virtualized infrastructure
- The backend server infrastructure includes significant amounts of disk storage space that must support simultaneous access by multiple users while providing adequate performance. In most virtualized environments, a Storage Area Network (SAN) is required. The acquisition, support, and maintenance costs for SAN storage is significantly higher than standard direct-attached storage, and much more so compared to desktop/workstation storage
- The backend storage must have adequate backups. Since the virtualized applications and desktops are being provided as a service to end users, the area IT Staff must ensure the storage is backed up on a nightly basis and must provide the means for recovery/restore at the end user's request
- The backend server and storage must be refreshed every 3 to 4 years. These costs must be factored into the long term plan for sustainability of the virtualized set of applications
- Increased complexity of the backend server and storage infrastructure requires more highly skilled technical staff and additional consulting service contracts
- While virtualization vendors are slowly making their solutions easier to manage, the combination of more advanced server hardware, SAN storage, backup infrastructure, licensing servers, and configuration complexity requires more advanced specially trained technical staff. IT Staff with standard experience maintaining departmental servers and storage may not have the required skills and training to manage the virtual environment
- Initial deployments often require additional paid consulting services from the virtualization vendor and/or their partners
- Extended support and additional support beyond normal working hours
- The virtual environment is a new experience for most end users. Users will need extra assistance in answering questions and troubleshooting various issues
- Virtualized services are generally available anywhere and anytime, so students, faculty, and staff will expect to have access at all times. Departments may not be prepared to receive and respond to end user issues outside of normal working hours. Additional support staff may be required to provide this extra level of expected service
- Virtualization has not demonstrated an overall cost savings for departments or the University
- While virtualization has benefits and is largely the future of computing, it does not lower overall computing costs, particularly for smaller deployments
- Pure cost savings can generally only be achieved at very large scales