However, challenges may arise with the transfer of virtual appliance ownership or transfer of virtual appliances between cloud data centers. The file format of the virtual appliance is the concern of the cloud provider and usually not relevant to the cloud user even though the cloud user may be the owner of the virtual appliance. Virtual appliances are critical resources in infrastructure as a service cloud computing.
Adding virtual appliances into the picture allows for extremely rapid provisioning of grid nodes and importantly, cleanly decouples the grid operator from the grid consumer by encapsulating all knowledge of the application within the virtual appliance. Virtualization solves a key problem in the grid computing arena – namely, the reality that any sufficiently large grid will inevitably consist of a wide variety of heterogeneous hardware and operating system configurations.
Most virtualization platforms, including those from VMware, Microsoft, Oracle, and Citrix, can install virtual appliances from an OVF file.
The Distributed Management Task Force (DMTF) publishes the OVF specification documentation. It may also be distributed as Open Virtual Appliance (OVA), the. The file format most commonly used is the Open Virtualization Format (OVF). Virtual appliances are provided to the user or customer as files, via either electronic downloads or physical distribution. A virtual appliance is usually built to host a single application it therefore represents a new way to deploy applications on a network. Many virtual appliances provide a Web page user interface to permit their configuration.
Like a physical computer, a hypervisor is merely a platform for running an operating system environment and does not provide application software itself. Like software appliances, virtual appliances are intended to eliminate the installation, configuration and maintenance costs associated with running complex stacks of software.Ī virtual appliance is not a complete virtual machine platform, but rather a software image containing a software stack designed to run on a virtual machine platform which may be a Type 1 or Type 2 hypervisor. Installation of a software appliance on a virtual machine and packaging that into an image creates a virtual appliance. A virtual appliance is a pre-configured virtual machine image, ready to run on a hypervisor virtual appliances are a subset of the broader class of software appliances.