OpenStack -- co-founded by Rackspace and NASA in 2010 -- certainly has the buzz, what with partnerships with AT&T, HP and IBM, to name a few, all of which have promised to use OpenStack as the base for their private cloud offerings.
CloudStack boasts $1 billion worth of business transactions annually running across their clouds since Citrix released the code (Citrix picked up the technology in its 2011, $200 million purchase of Cloud.com) into the Apache open source realm in April 2012.
And Eucalyptus -- the longest-standing open source project of the three -- is banking on its very tight technical ties to Amazon Web Services (AWS) to convince enterprises to go the hybrid route, running their private clouds on the Eucalyptus stack and seamlessly bursting into the Amazon public cloud when necessary.
Those are the strategic battle cries as the factions spar for positioning as the open source infrastructure as a service (IaaS) stack most tapped into for building enterprise private clouds.
According to a study on data center expansion plans by Campos Research & Analysis and paid for by data center solution provider Digital Realty Trust, three in five respondents -- 300 IT decision makers at large corporations in North America were interviewed for the study said that building a private cloud was a primary impetus for their future data center build-out plans.
According to a new forecast report by IDC, worldwide spending on hosted private cloud (HPC) will grow to be more than $24 billion by 2016.
While most independent sources interviewed for this story contend that OpenStack is a likely front runner, they all refused to pick an ultimate winner, given that both the definition of private cloud and statistics about the rate at which enterprises are deploying and taking advantage of private clouds have been slippery little devils to pin down.
"What I can say, though, is that having three open source cloud stack options jockeying for position as the best one out there does bode well for one of them getting to widespread adoption in the enterprise in the future," says Aneel Lakhani, research director for virtualization and cloud at Gartner.
Open source cloud platforms are attractive for the same reasons Linux took hold, low cost point of entry and the prospect of application portability.
Deep dive into the differences
There are certainly technical differences between the three open source stacks. Independent cloud application development consultant Daniel Kranowski of Business Algorithm, in a talk at the JavaOne conference in late last year, gave a thorough comparison of the stacks based on their architecture, installation, administrative capabilities, security and high availability.
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