Chances are good that you’ve run into an OVF/OVA from a variety of sources: as a packaged application or appliance from a vendor, as a download from the VMware community appliances site, or even while physically moving virtual machine files from one location to another.
I admit, when I first started administering VMware, I didn’t understand what an OVF or an OVA were, and what their differences are. In order to best understand the differences between the two, let’s take a look at what an OVF is first.
An OVF refers to the Open Virtualization Format, which is a “packaging standard designed to address the portability and deployment of virtualization appliances” (Source). The OVF format standard was formed by the Distributed Management Task Force, or DMTF, which is an industry working group comprised of over 160 member companies and organizations. The DMTF board is comprised of 15 technology companies and includes Dell, EMC, VMware, Oracle, & Microsoft. As announced at VMworld 2010, DMTF’s OVF standard was adopted as a National Standard by ANSI.
An OVF package structure consists of a number of files: a descriptor file, optional manifest and certificate files, optional disk images, and optional resource files (such as ISO’s). The optional disk image files can be VMware vmdk’s, or any other supported disk image file. More information about the OVF format standard can be found here.
OVA and OVF: The Differences
OVF is not only the name of the packaging format standard, but it also refers to the package when distributed as a group of files. An OVA (open virtual appliance or application) is merely a single file distribution of the same file package, stored in the TAR format.