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Curbing VM sprawl with server capacity planning, lifecycle management

VM sprawl is one of the most common virtualization problems. Server capacity planning and virtualization lifecycle management strategies can help prevent VM sprawl.

Virtualization is not a one-time effort. Virtualization problems can and do develop over time -- even when everything else is working properly.

 For example, the uncontrolled proliferation of virtual machines, called VM sprawl, can gradually choke the remaining processing power from servers. VM sprawl can degrade the performance of other VMs, cause unexpected crashes and prevent the proper failover of VMs from other troubled servers. Upgrades and patches to underlying virtualization platforms can also have unforeseen consequences for performance and stability.

As a result, administrators must be proactive in preventing VM sprawl and other virtualization problems as they emerge. Let's take a look at some of the best strategies.

Virtualization lifecycle management and performance monitoring
Virtualization lifecycle management is one tactic that can help manage VMs -- ensuring that only justifiable VMs are created by authorized administrators, that they're used actively and finally removed to free computing resources for other VMs.

Performance monitoring tools will gauge resource usage for tangible factors like network bandwidth, disk I/O and CPU use. When tracked over time, resource load trends can flag potential trouble spots that should be investigated. Almost all performance monitoring tools include email/SNMP traps that will warn administrators when key resources fall outside of established limitations. Identifying sudden alarming shifts in resource use can signal early warnings that are essential for quick resolution and minimal disruption to the production environment.

"You should know there's a problem before the end user knows," said Todd Erickson, chief operations officer and senior vice president of First Flight Federal Credit Union, a financial institution in Havelock, N.C.

Server capacity planning and documentation
Ongoing performance monitoring is also essential to accurate server capacity planning. By watching the trends, administrators can make informed decisions and budget for future upgrades that will accommodate the long-term growth of a business.

"You do more capacity planning in a virtual environment than you ever thought you would in a physical setting," said Ty Hacker, director of technical services at I-Business Network LLC, a financial/accounting Software as a Service provider located in Marietta, Ga.

Server capacity planning is far more preferable -- and usually less expensive -- than ignoring performance problems until they reach crisis levels.

The final element in preventing virtualization problems is thorough, accurate and well-maintained documentation. It's easy to forget the vast amount of details found in a virtual setting. So keep a record of supporting documentation to ensure that your repairs, restorations, upgrades and improvements will go smoothly.

About the author
Stephen J. Bigelow, a senior technology writer in the Data Center and Virtualization Media Group at TechTarget Inc., has more than 15 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

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