The potential challenges of virtual appliances

Insightful analysis by consultants Steve Taylor and Jim Metzler, plus links to the latest WAN news headlines

In our last newsletter we discussed some of the benefits of virtual appliances. In this newsletter we will discuss some of the potential challenges that are associated with virtual appliances.

VDI shootout 

One of the potential challenges of a virtual appliance is performance. The conventional wisdom in our industry is that a solution that is based on dedicated, purpose-built hardware performs better than a solution in which software is ported to a generic piece of hardware, particularly if that hardware is supporting multiple applications. 

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In our last newsletter we discussed some of the benefits of virtual appliances. In this newsletter we will discuss some of the potential challenges that are associated with virtual appliances.

VDI shootout 

One of the potential challenges of a virtual appliance is performance. The conventional wisdom in our industry is that a solution that is based on dedicated, purpose-built hardware performs better than a solution in which software is ported to a generic piece of hardware, particularly if that hardware is supporting multiple applications. 

However, the conventional wisdom is often wrong. Some of the factors that enable a virtualized appliance to provide high performance include the fact that based on Moore's law the price-performance ratio of computing doubles every 18 months. Another factor that improves the performance of a virtual appliance is the fact that most servers come with multiple core processors that further increase server performance. Because of factors such as these, IT organizations should evaluate the performance of a virtual appliance to determine if the virtual appliance can provide the necessary performance.

Another one of the potential challenges of a virtual appliance is the degree of integration of the virtual appliance with the virtual server management system. Ideally this management system would recognize the virtual appliances as another type of virtual machine (VM) and understand the associations between the appliance VM and application VMs in order to allow a coordinated migration between physical servers whenever this is desirable. 

In addition to VM migration, integration with the virtual server management system should support other management features, such as resource scheduling and load balancing. An example of this happening is when the system manager can increase the resources available to virtual appliances to meet periodic surges in application traffic. Resource changes can be made manually, scheduled, or automatically triggered by changes in performance levels. 

Dynamic allocation of resources facilitates higher degrees of virtual server and virtual appliance consolidation in both the data center and the remote branch office.

More information on the benefits, challenges and solutions that are associated with virtualization can be found in Jim's recent report. In addition, at the forthcoming Interop conference in New York City, Jim will be moderating a session entitled The Emergence of Virtualized Application Delivery Appliances. If you are going to be at Interop, you should plan on attending that session.

Read more about lans & wans in Network World's LANs & WANs section.

Steve Taylor is president of Distributed Networking Associates and publisher/editor-in-chief of Webtorials. Jim Metzler is vice president of Ashton, Metzler & Associates.