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Report - Zombie and Comatose Servers Redux, April 2017 - Jon Taylor and Jonathan Koomey

30 March 2017

In 2015, Jon Taylor of the Anthesis Group in partnership with Jonathan Koomey Research Fellow at Stanford University, published a report revealing that 30 % of enterprise servers in the five facility, 4000 server sample were comatose, performing no useful computing over a 6 month period in 2014.

Zombie Servers Redux - an introduction

The problem of servers that use electricity but deliver no useful information services, (known as zombie or comatose servers) is one that continues to haunt the data center industry. Few companies can identify these orphaned servers, and many companies don’t even know how many servers they have.

In previous work, we showed that about thirty percent of the enterprise servers were comatose in a 4000 server sample across five data center environments, performing no useful computing over a six month period in 2014. This finding mirrored earlier work by the Uptime Institute and McKinsey and Company, which showed very low server utilization and significant percentages of zombie servers in enterprise data centers.

In this follow-up analysis, we assess the percentage of comatose servers in a sample four times larger than included in our original report (and covering twice as many facilities) using a consistent methodology and data from TSO Logic’s data discovery tools. This report summarizes these new results, which includes an assessment of comatose physical servers as well as comatose virtual machines running on hypervisors.

Download a copy of the report

For more information please contact Jon Taylor, or alternatively, use our fill out form below:


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