With the imminent release of Windows Server 2016, due to be launched some time in September with its new per-core licensing, Microsoft is making a concerted effort to win over VMware users and get them to switch to Hyper-V.

Accordingly, the company is running a time-limited promotion: switch from VMware to Hyper-V and the company will give you "free" licenses to Windows Server Datacenter. The catch is that you'll need to buy a Software Assurance subscription, too, so it's not really free. But it should save some of the costs of migrating.

To help persuade companies to switch, Microsoft has offered a TCO calculator to show off the big savings (Microsoft hopes) that can be had from making the switch.

The company is offering a similar promotion for companies that are willing to switch from Oracle to SQL Server 2016; "free" licenses with purchase of Software Assurance.

That Microsoft is gunning for VMware customers is no big surprise; VMware is the market leader here, with Hyper-V a relative latecomer to the scene. VMware is still a leader in Gartner's magic quadrants, but Hyper-V is moving up and to the right, signaling to CTOs and other executives that Hyper-V is an increasingly capable platform. With new platform-level features in Windows Server 2016, such as Storage Spaces Direct (a new system for creating clustered, resilient storage volumes across both SSDs and spinning disks) and Shielded Virtual Machines (that offer some protection to a VM even if the host is compromised), Microsoft is trying to push Hyper-V's capabilities further to make it scale better and be easier to manage.

But this is a more aggressive push than we've seen in the past. Large companies have always been able to negotiate pricing discounts, but this is rather different; as a blanket offering, it takes out negotiation and discounts. Hyper-V's market share has been steadily encroaching on VMware's for a number of years; this promotion should help further close that gap, perhaps even putting Hyper-V on a path to overtaking the dominant incumbent.