OpenNebula 4.4 Retina

Dec 3rd, 2013. The OpenNebula team is pleased to approach winter with the immediate availability of the final version of OpenNebula 4.4, codename Retina. As a project driven by user needs, this release includes important features that meet real demands from production environments, with a focus on optimization of storage, monitoring, cloud bursting, and public cloud interfaces.

OpenNebula Retina includes support for multiple system datastores, which enables a much more efficient usage of the storage resources for running Virtual Machines. This feature ships with different scheduling policies for storage load balancing, intended to instruct OpenNebula to spread the running Virtual Machines across different storage mediums to optimize their use. This translates in the ability to define more than one disk (or other backend) to hold running VMs in a particular cluster. Monitoring subsystem in OpenNebula underwent a major redesign as well, effectively switching from a pulling mechanism to a pushing model, with the implications in scalability improvements.

An important effort has been made in the hybrid cloud model (cloud bursting). Using the AWS API tools have been deprecated in favor of the new Ruby SDK released, which allows the support of new AWS mechanisms like for instance IAM. Also, now is possible to fully support hybrid VM templates. Moreover, the AWS public cloud interface implemented by OpenNebula has been revisited and extended to support new functionality, as well as improved so the instance types are offered to the end user from OpenNebula templates.

This is a stable release and so a recommended update that incorporates several bug fixes since 4.4 RC. We've done our best to keep compatibility with OpenNebula 4.2, so any application developed for previous versions should work without effort. In any case, be sure to check the compatibility and upgrade guides.

As usual OpenNebula releases are named after a Nebula. The Retina Nebula (IC 4406) is a planetary nebula near the western border of the constellation Lupus, the Wolf. It has dust clouds and has the shape of a torus.

What is Hot in OpenNebula 4.4?

What's New in OpenNebula 4.4

In the following list you can check the highlights of OpenNebula 4.4 Retina organised by component (a detailed list of changes can be found here):

OpenNebula Core: End-user functionality

OpenNebula 4.4 brings multiple new features to manage virtual machines:

OpenNebula Core: Internals & Administration Interface

There has been also several improvements for administrators and new features to enhance the robustness and scalability of OpenNebula core:

OpenNebula Drivers

The back-end of OpenNebula has been also improved in several areas, as described below:

Storage Drivers

Monitorization Drivers

  • New monitorization model, changed from a pull model to a push model, thus increasing the scalability of an OpenNebula cloud. More information here

Virtualization Drivers

  • VMware drivers improvements, like maintaining cloned target image format, improved vCenter integration

Networking Drivers

  • Security improvements in Open vSwitch, block ARP cache poisoning.


  • Support for cloud init, now OpenNebula is able to contextualize guests using cloud init.
  • Improvements in contextualization, ability to add INIT_SCRIPTS. Check this guide to learn how to define contextualization in your VM templates.

EC2 Public Cloud Improvements

Multiple improvements in the EC2 Public API exposed by OpenNebula:

  • VM snapshotting and VM tagging. Read this for more info on the offered EC2 functionality.
  • Better use of ONE templates in EC2 API, check more details here.

Cloud Bursting Improvements

The cloud bursting (previously called hybrid) drivers have been improved in a variety of areas:

  • Allow mixed templates, ability to have templates defining VMs locally and in Amazon EC2. More info here.
  • Adoption of Ruby SDK, for a better interaction with AWS.
  • EBS optimized option, now it can be passed to an Amazon VM. More info on EC2 specific template attributes.
  • Extended host share variables, to cope with big regions modelled in OpenNebula.


  • Improved Apache integration, to allow uploading big images. More info on Apache and Sunstone integration here.
  • Better memcache integration, for more details on Sunstone for large scale deployments check this.
  • Multiple minor bugfixes: adding multiple tags of the same name, VM template wizard context fixes and updating, update quotas, attach disks problems, time format inconsistencies, tons of new tooltips, fixed typos, etc

Migrating from OpenNebula 4.2

A detailed upgrade process can be found in the documentation. For a complete set of changes to migrate from a 4.4 installation please refer to the Compatibility Guide.

:!: With the new multi-system DS functionality, it is now required that the system DS is also part of the cluster. If you are using System DS 0 for Hosts inside a Cluster, any VM saved (stop, suspend, undeploy) will not be able to be resumed after the upgrade process.

:!: After the OpenNebula upgrade make sure you run “onehost sync” to update the monitoring probes.

Getting the Software & Documentation

OpenNebula is released under the Apache 2.0 open source license. The complete source tree and binary packages for OpenNebula can be downloaded here.

Packages are available for various distros: Ubuntu LTS and latest, CentOS, OpenSUSE and Debian.

Please report any bug or send feedback at the development portal or at the mailing list.

The documentation of OpenNebula 4.4 can be found here.

Supported Platform Components

Because OpenNebula is inherently portable to different operating systems and virtualization platforms, most Linux distributions and Hypervisors are supported. However, not all platform configurations and combinations exhibit a similar functionality, performance and stability. You can contact us if you need advise about the best platform configurations and environments for functionality and performance. Please read our Certification Policy for more information.

Certified Platform Components

This is the list of the individual platform components that have been through the complete OpenNebula Quality Assurance and Certification Process.

Certified Platform Component Version
RedHat Enterprise Linux 6.4
Ubuntu Server 12.04 (LTS) & 13.04 (Latest)
SUSE Linux Enterprise 12.3
CentOS 6.4
openSUSE 12.3
Debian 7.1
VMware ESX 5.0 & ESX 5.1
Xen 3.2 & 4.2
KVM Supported version that is included in the kernel for the Linux distribution
Xen Server, Xen Cloud Platform, and Hyper-V  Please contact us if you are interested in these hypervisors


The OpenNebula project would like to thank the community members and users who have contributed to this software release by being active with the discussions, answering user questions, or providing patches for bugfixes, features and documentation.

About OpenNebula

More information about the project can be found at the project web page. You may be also interested in checking the OpenNebula Addons Catalog that includes several projects contributed by the community to enhance or add new features to OpenNebula.