VMs, hypervisors, and clouds – app images vs machine images

Because appzero uses application images, not machine images (virtual machine/VM) ….

• appzero works with any hypervisor = appzero is hypervisor-agnostic
• appzero VAAs can move from hypervisor to hypervisor without alteration
• appzero is cloud independent
• appzero VAAs run on both physical and virtual machines

Virtual machines (VM) are great for provisioning servers, but not for provisioning server applications:

• Machine image approach: Virtual machines (VM) have the OS hosted as a guest in a dedicated virtual environment. This approach completely isolates one OS from another, but proliferation of VM and OS instances can create a management challenge.
• Virtual appliances (VA) package an application with a Virtual Machine (VM).
• The interdependencies between an application and its underlying infrastructure, introduced at installation, remain as rigid in the VA/VM world as in the world of physical servers.
• VAs inherit the performance overhead of the hypervisor approach.

Additionally, Microsoft licensing becomes a cost consideration when any part of an OS is incorporated into a VA. The economics of maintaining server-side applications are not positively changed in this model.

By contrast, appzero takes an application image approach to deploying server applications:

• appzero application image  approach: encapsulates an application in an appzero virtual application appliance (VAA) package without a virtual machine (VM)
• Applications are not installed, but are run with a ‘copy and run’
• Applications encapsulated by appzero will have an image size that is 10-100 times smaller than the same application packaged with a machine image. 
• appzero makes server-side applications moveable to, from, and across any cloud or machine (physical or virtual) anywhere, in minutes and hours vs days and weeks (3 patents granted).

This approach completely decouples an application from the OS and its underlying infrastructure, avoiding OS licensing issues. appzero is designed specifically for the virtualization of server-side applications.

Applications can be maintained and updated in isolation from other execution elements such as web server and database engine. The reverse is true as well. VAAs contain applications that are pre-installed and pre-configured, able to be up and running with a copy and run.  Applications in VAAs are completely portable from server to server, whether physical or virtual, in the datacenter, hosted, or in any cloud (public, private, hybrid, and federated).

Performance

The use of hypervisor technology has an impact on overall system performance. The use of appzero VAAs has negligible impact on overall system performance.