IT administrators should exercise caution in their server consolidation plan, especially when it comes to moving resource-intensive applications into the virtual domain.
Server consolidation offers plenty of benefits, but over-consolidation is a common pitfall, and placing resource-intensive applications on virtual machines (VMs) could cause resource contention.
Old applications can be particularly problematic during server consolidation—especially applications that are custom-built or otherwise rely on direct interaction with specific hardware. Because virtualization imposes a layer of abstraction between the application and the underlying hardware, any applications that “need” access to specific hardware may malfunction or experience unacceptable performance issues.
One solution here is to update the application using newer programming languages and techniques to create a more hardware-agnostic version. However, such upgrades can be costly and time-consuming. Similarly, it might be possible to replace the custom application with a commercial product that you can customize in-house to accomplish the same tasks. But the time and effort needed to customize the commercial application may sometimes be more than the resources needed to update the existing application.
When server consolidation just doesn’t make sense
Instead of bringing in server consolidation, it’s often easiest to simply leave the custom application running on a non-virtualized physical server. Just because an application can exist as a VM does not mean it should—or even could—be consolidated.
Consider a demanding application such as SQL Server or Exchange Server. It is possible to run SQL or Exchange as a VM, but it’s doubtful that you would get acceptable performance out of the application if it’s forced to share computing resources with 10 or more other VMs on the same physical machine. Demanding or resource-intensive applications are best approached with minimal levels of server consolidation.
Testing is an important part of the server consolidation process and should be performed in a lab environment that doesn’t impinge on the production data center. Server consolidation testing ensures that even those resource-intensive applications are suitable for a virtual environment, verifies the computing resources required, provides insights into performance, and checks interoperability in the virtual environment.
Stephen J. Bigelow, a senior technology editor in the Data Center and Virtualization Media Group at TechTarget Inc., has more than 20 years of technical writing experience in the PC/technology industry. He holds a bachelor of science in electrical engineering, along with CompTIA A+, Network+, Security+ and Server+ certifications and has written hundreds of articles and more than 15 feature books on computer troubleshooting, including Bigelow’s PC Hardware Desk Reference and Bigelow’s PC Hardware Annoyances. Contact him at email@example.com.
This was first published in June 2011