VMware : What’s the difference between OVF and the OVA VM appliance?

One question that I received from the previous blog post was, “What’s the difference between OVF and OVA?

What is an OVF file?

OVF: Open Virtualization Format. The Open Source Virtualization Format OVF file is a specification that describes an open-source, secure, efficient, and extensible portable virtual packaging and software distribution format.

It generally consists of several parts:

  • OVF file: plays an essential role in the OVF file format. It ensures the correct mapping between the image file VMDK, resource file ISO, and VM configurations. The function is similar to the VMX format in VMware and the XML configuration files in Xen and KVM.
  • mf file: is a collection of file SHAs. It is used to prevent image files from being tampered with by unauthorized users.
  • Cert file: checks whether VM configurations are maliciously tampered with. How do we ensure the validity of the mf file? So we need a. Cert file to supplement it. The Cert file consists of two parts: the digest of the mf file and the certificate content of the valid certificate. The certificate is used to verify the validity of the mf file, which further proves the validity of the entire OVF file package. The generation of Cert certificates depends on PKI and can be implemented using OpenSSL.
  • VMDK and ISO files: The two types of files belong to the same type. In the OVF, they are resource classes, mainly specific image resources. The difference is that the VMDK file content is mainly the user operating system (OS) content, while the ISO file content is the content of the CD-ROM drive.

What is an OVA file?

Open Virtualization Appliance: The single file format combines components into a single file. An OVF file can be regarded as a package consisting of several specified types of files. The file package can be used as a standard and reliable virtual file format between different VMs in the future to implement commonality between them. Each type of file has its own role and complements the others.

What is the difference between the OVA file and the OVF file?

OVF and OVA contain all the necessary information for deploying VMs. The Distributed Management Task Force (DMTF) defines both package encapsulation formats.

The main difference between the two is in the description and encapsulation of the package.

The OVF package constructs several necessary files for defining and deploying VMs, while the OVA package is a single file in which all the necessary information is encapsulated.

The OVF file uses the .ovf file extension, an OVF descriptor, and an XML file that describes the packaged virtual machine.

On the other hand, OVA files have the .zip file extension and contain all the file types in an OVF package.

Enjoy!

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