A useful metric to determine IT administration efficiency is the administrator-to-virtual machine (VM) ratio. The admin-to-VM ratio measures how many VMs each administrator can manage. This tip examines recent EMA research that illustrates the benefits of a low admin-to-VM ratio and which virtualization management tools can help you achieve one.The benefits of high admin-to-VM ratios
The admin-to-VM ratio is unique to virtualization but is analogous to the standard administrator-to-server ratio in
A low admin-to-VM ratio indicates an ability to support a growing business because more servers can be added to the environment with a minimal increase in administrators and costs. It also indicates that an IT environment is agile and innovative.
EMA's study "Virtualization Metrics and Recommendations for Enterprises" has found that the average enterprise admin-to-VM ratio is about 1: 77. So in a typical environment, each administrator can manage about 77 virtual machines. But the best performers can exceed this number and have ratios of 1:150.
One outlying -- but statistically significant -- group has exceptional administrative efficiency because it can manage as many as 1,800 VMs per administrator. By contrast, below-average organizations were 100 times less efficient than the outlying group, with an average admin-to-VM ratio of 1:18.
With an average data center staffing cost of $67,860 (according to the EMA research report Data Center Automation: Delivering Fast, Efficient, and Reliable IT Services), each VM added to an environment costs the best performers $452 in additional administration staff costs and $881 for above-average performers. For below-average performers, each additional VM costs a disturbing $3,770.Tools for improving admin-to-VM ratios
EMA research on virtual systems management (VSM) found that adhering to best practices in specific VSM disciplines correlated strongly with the best results in this metric. After analyzing the survey respondents' environments, the best performers in admin-to-VM ratios were found to employ the following VSM disciplines:
- Among respondents, 39% use change and configuration management software. Technologies such as Tripwire Enterprise (or its freeware tools, ConfigCheck and OpsCheck), and IBM Tivoli Configuration Management provide automated detection of configuration changes in virtual environments so administrators don't waste time manually fixing unauthorized changes. In a published EMA case study, a large student loan provider reported reducing admin involvement in compliance audits from three hours to about 45 minutes by deploying change and configuration management software.
- Among respondents, 37% use discovery and inventory management software. Options like BDNA Insight, ManageIQ EVM Insight, and BMC Discovery allow IT administrators to examine and record physical server use, VM deployments and application utilization. IT administrators can then spend less time looking for spare equipment and software licenses when they get a new deployment request. In an upcoming EMA case study, a New York Stock Exchange-listed financial services firm saved several million dollars by deploying discovery and inventory management software.
- Among respondents, 36% use capacity planning and management software. Software offerings such as HP Insight Dynamics VSE, Novell PlateSpin Recon, VKernel Capacity Analyzer, and CiRBA Capacity Management help administrators locate available servers for new workloads, and find spare capacity to allocate to peaking workloads. When paired with VM management technologies, administrators spend less time on mundane activities like measurement, cataloging and provisioning of servers and resources, leaving them time to perform more strategic tasks and manage more servers.
- Among respondents, 27% use remote control, or out-of-band, software. Technologies such as Avocent DSView and Raritan CommandCenter Secure Gateway (especially when coupled with hardware features such as Intel vPro with AMT and HP iLo) allow IT administrators to remotely manage physical servers down to the hardware layer. Admins can perform low-level maintenance activities such as server rebooting, applying BIOS updates, activating chip-level paravirtualization support, managing power usage and applying firmware updates without wasting time in a separate server room (or in many cases traveling to a remote site to get at a physical server console).
- Among respondents, 24% use virtual machine management. Software such as VMware Infrastructure (with vCenter and VMotion), Citrix XenServer (with XenCenter and XenMotion), and Microsoft's Virtual Machine Manager (with Hyper-V Quick Migration), take a load off an administrator's shoulders. By automatically performing routine management tasks such as virtual machine migration and provisioning, administrators can devote more time to managing complex virtual systems and additional virtual servers.
EMA research has found other VSM disciplines and tools deliver positive outcomes for admin-to-VM ratios, including compliance auditing and reporting, performance and availability monitoring, and automated provisioning. Achieving high admin-to-VM ratios also depends on other factors such as workload size and admin skills. By using these VSM products and best practices, enterprises are likely to improve admin-to-VM ratios and build more effective server virtualization deployments.
|Andi Mann, is a research director with the IT analyst firm Enterprise Management Associates (EMA). Mann has over 20 years of IT experience in both technical and management roles, working with enterprise systems and software on mainframes, midrange, servers, and desktops. Mann leads the EMA Systems Management research practice, with a personal focus on data center automation and virtualization. For more information, visit EMA's website|
This was first published in May 2009