OVirt is an open source data center virtualization platform developed and promoted by Red Hat.
OVirt, which offers large-scale, centralized management for server and desktop virtualization, was designed as an open source alternative to VMware vCenter.
OVirt provides kernel-based virtual machine management for multi-node virtualization. Kernel-based Virtual Machines (KVMs) are part of a virtualization infrastructure that turns the Linux kernel into a hypervisor.
Features of oVirt
OVirt provides centralized management of VMs, networking configurations, hosts, and compute and storage resources from a web-based front end. OVirt also offers features for disaster recovery (DR) and hyper-converged infrastructure deployments.
Network management provides IT administrators with the ability to bridge multiple virtual LANs to network interfaces. This enables admins to configure IP addresses and subnet masks via managed nodes that are supported through the web interface.
Features for the management of compute resources include CPU pinning, same-page merging and memory overcommitment. CPU pinning enables oVirt to bind and unbind processes and threads with CPUs to reduce cache issues. Admins can also utilize same-page merging, which can enable a system to share copied memory pages with different virtual guests and processes. Memory overcommitment enables a VM to use more memory than is available to the physical host.
VM management features include live migrations, live snapshots, the creation of VM templates and VMs, as well as automated configuration when provisioning and deploying VMs. Live snapshots enable admins to take a snapshot of a VM while the VM is still running. Admins can create VMs from a template, clone or by manually using oVirt. They can also boot the VM from multiple sources, such as a hard disk or ISO image.
DR features include inputting storage domains to different instances. Admins can then manage data replication from oVirt.
OVirt uses both self-hosted and Gluster Storage domains for centralized management. Admins can expand the available resources by adding more nodes to a cluster.
Components of oVirt
OVirt is built on Red Hat Virtualization management code, a KVM hypervisor, an oVirt node to run VMs and virtualization tools such as libvirt. It can use locally attached storage, Network File System (NFS), iSCSI or Fibre Channel interfaces to communicate with host servers.
Two major parts of oVirt are the oVirt engine and the oVirt node, which admins can deploy in a VM as a self-hosted engine.
The oVirt engine acts as the control center for oVirt environments. The engine enables admins to define hosts and networks, as well as to add storage, create VMs and manage user permissions. Included in the oVirt engine is a graphical user interface (GUI), which manages oVirt infrastructure resources. The oVirt engine can be installed on a stand-alone server or in a node cluster in a VM.
The oVirt node is a server that runs on CentOS, Fedora or Red Hat Enterprise Linux with a virtual desktop and server manager (VDSM) daemon and KVM hypervisor. The VDSM controls the resources available to the node, including compute, networking and storage resources.
Versions of oVirt
With new versions of oVirt have come new features and fixes. For example, version 3.1 added live snapshots, network adapter hot plugging and support for accessing externally hosted logical unit numbers from VMs.
Version 3.2.1 added support to remove VMs and keep VM disks as floating disks -- but only when the disk isn't based on a template and doesn't have snapshots. Version 3.2.1 also added cloud provider inventory reports, which display a list of VMs organized by cluster or data center. Support for live snapshots was also added in this update.
Version 4.0.2 added a warning message to notify admins if the system isn't in global maintenance mode when the engine is running on the hosted engine configuration. If the engine setup is running while the system isn't on global maintenance mode, data corruption can occur.
Version 4.2.1 added support for a file output plugin to the ovirt-engine-metrics setup, which enables ovirt-engine-metrics setup to debug metrics sent to a local file. Processes such as enabling admins to upload to the oVirt data center simplify importing VMs created outside of the data center. This update also enables API functions to run while plugins load. Admins can run APIs such as loginUserName, loginUserld, ssoToken, engineBaseUrl or currentLocale while loading a plugin.
OVirt version 4.2.7 was released in November 2018. Version 4.2.7 features image-based, oVirt engine and VDSM-centric updates. For example, with oVirt 4.2.7, admins can recover from failed upgrades if an image base fails. The oVirt engine limits east-west traffic of VMs using a network filter.
VDSM updates include the ability to copy volumes to preallocated disks using out-of-order writing, which enables write actions, such as moving, importing or copying disks to preallocated storage, to be six times faster than was previously possible in oVirt. Bug fixes include a fix for a bug where a VM fails to start if the maxMemory is above or equal to 2048 GB.
oVirt vs. Proxmox
Proxmox Virtual Environment is an open source server virtualization management platform. Admins can use Promox to set up, deploy or manage virtual environments to enable the use of snapshots and server migration. Other features include dynamic resource updates and the creation of virtual servers and VMs.
Management options are available via a web-based interface. VM images can be stored in a local storage area or NFS.
oVirt vs. OpenStack
OpenStack is another open source tool comparable to oVirt. Even though these products are similar, OpenStack is an infrastructure-as-a-service (IaaS) platform working on a larger scale in terms of nodes and tenants, enabling admins to focus on how they run a large cloud service in their data centers.
oVirt vs. VMware vSphere
VMware vSphere is a leader in the server virtualization and management marketplace. It's considered the standard when it comes to virtualization, but some admins might find its licensing too pricey.
oVirt vs. XenServer
XenServer is a server virtualization product provided by Citrix. XenServer runs directly on server hardware and is optimized for Windows and Linux virtual servers. However, there are no instant recovery or incremental backup options in XenServer like those in other virtualization tools.