There appears to be a challenger to 'VM sprawl' as the scourge of virtualization success \u2014 a problem I call 'VM stall'.We know about 'VM sprawl' \u2014 because new virtual machines are so easy to deploy, organizations can end up with more VMs that they can \n\nhandle, or even use. This has the potential to cause severe problems to availability, performance, compliance, costs, security, and more.However, I am seeing more and more evidence of this new phenomenon I think of as 'VM stall' \u2014 the tendency for virtualization \n\ndeployments to stall once the 'low-hanging fruit' has been converted (typically around 20-30 percent of servers).I think it happens more or less like this...In general, organizations start virtualization deployments by converting relatively low-risk, low-impact systems \u2014 dev\/test servers, Web \n\nservers, file servers, internal applications, etc. \u2014 to virtualization. With a big impact, great results, and reasonably fast and easy implementation, it \n\nis a great hit with IT and business owners. This may even spawn a 'virtual first' initiative, where all new server requests are deployed as virtual servers by \n\ndefault.However, when faced with the next step, converting the remaining existing servers \u2014 including tier 1 business services, customer-facing \n\nenvironments, enterprise-wide systems, third-party applications, multi-platform services, and composite applications \u2014 virtualization projects \n\noften stall.I was interested to see the notion of VM stall confirmed in some new research into virtualization coming \n\nout of Prism Microsystems, a software vendor in the SIEM market.One of the most interesting outcomes in this research was again the low penetration of server virtualization within each organization. As the chart \n\nbelow shows, most organizations have still virtualized less than a third of their production servers.What's more, fully 15 percent have not even started to virtualize their production servers at all!It might seem that this is really at odds with 'the common wisdom' that sees virtualization as mature, ubiquitous, commoditized, and even \n\npass\u00e9. We hear so much about virtualization, how it has been a top priority for years, about how everyone is deploying virtualization. For \n\nexample:The IBM Global CIO Study 2009 in \n\nSeptember showed 76 percent of 2500 global CIOs are undergoing or planning virtualization projects.\nThe Gartner 2010 CIO Survey in January reported that \n\nvirtualization is the top priority for over 1,500 global CIOs (up from number 3 the previous year).\nIn January, CDW's Server Virtualization Life Cycle Report (registration required) found that 90 percent of respondents have implemented server \n\nvirtualization at some level.\nAs far back as 2008, EMA research showed 75 percent of \n\nenterprises were using virtualization for production use cases.\nThe Prism Microsystems report the chart above comes from states that 85 percent of their sample have adopted virtualization to some \n\ndegree.I am even starting to hear that virtualization is set to be irrelevant, becoming nothing more than just a stepping stone to cloud.However, despite the widespread adoption of virtualization as a percentage of organizations, it is consistently still very low as a percentage of \n\nproduction servers.Indeed, this is not the only recent (and not so recent) research study to highlight this issue. Over time, CIOs have reported a persistent difficulty in \n\nexpanding their virtualization deployments beyond the initial 20-30 percent of servers. For example:Around 6 months ago, Gartner reported that "only 16 \n\npercent of workloads are running in virtual machines today."