RHV Plugin: Architecture

Enterprise

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The following chapter describes the architecture of the RHV Plugin.

The Red Hat Virtualization Plugin is a File Daemon plugin.

It may be installed on a machine inside or outside of your RHV environment.

It is based on a Java SDK, therefore is non-machine dependent and is compatible with any Operating System where the Bacula File Daemon can run and the Java Virtual Machine is available.

Plugin Architecture

Plugin Architecture

Red Hat Virtualization Technology

Red Hat Virtualization (RHV) is a full virtualization platform capable of managing the full set of features that make up a virtualized data center: Hosts, networks, local, remote, or distributed storage. Management, accounting and monitoring are done through an API-based Web interface, which implements users and roles to implement access restrictions.

RHV is based on the open source OVirt virtualization platform. OVirt is available for Linux distributions related to RHEL. OVirt is under active development, and RHEL integrates releases they consider mature. Therefore, Ovirt itself can typically exist in newer versions than what is part of RHV.

RHV is composed of the following elements:

RHV Manager

is the service offering management through a web interface and APIs.

Virtualization Hosts
are the hypervisors providing their resources to the virtual machines. They are managed through the RHV Manager, and are based on the KVM system.
Two kinds of hosts are available:
RHEL hypervisors

being standard RHEL server systems

oVirt nodes

are minimal servers which are distributed as ISO images to install a lean virtualization platform solely for RHV usage.

There are 2 ways to deploy the RHV Manager: Standalone, with the RHV Manager running on a host outside of the virtualized environment, which does not provide native high availability, but is easily deployed and managed, and self-hosted, where RHV Manager runs inside the virtualized environment, in a dedicated VM.

The latter approach can be a highly available service by making use of the ovirt-ha-agent and virt-ha-broker services.

General Architecture (Standalone mode)

General Architecture (Standalone mode)

RHV Manager Architecture

RHV Manager Architecture

RHV Host Architecture

RHV Host Architecture

In figure RHV Host Architecture, the architecture of a virtualization host is shown. The stack of technologies employed by a host to provide a VM consists of the following elements:

VDSM

is the host agent service running on every virtualization host to provide the hypervisor service to the RHV system. This services listens on the TCP port 54321 on the network.

libvirt

is the toolkit that manages virtual machines.

QEMU

is the multi-platform emulator which provides emulation of full systems, including CPU capabilities not available on the underlying system.

KVM

is the kernel module which provides the system integration component to QEMU. It allows to execute guest VMs in user space, ensuring full segregation of VMs from each other and the host system.

SPICE

is the interface between virtualized user-facing components and remote interfaces, providing input, display, and sound services to remote interfaces (the “viewer” program).

Other important concepts to understand a RHV system are

Datacenter

is the most high-level group of virtualization systems, the VMs managed in it, and all the resources available.

Cluster

refers to a group of virtualization hosts (sharing networks, storage, and some other infrastructure properties). A Cluster is always part of a distinct Datacenter, and a Datacenter can consist of more than one Cluster.

Storage Domain

indicates a logical entity providing storage capacity to Virtual Machines of a Datacenter.

Storage Pool Manager

is the role of a certain host in the datacenter which creates, manages, and removes virtual disk images.

Template

is the base configuration of vms. This configuration can be from the architecture of the processor that will use the vm to the disks attached to it.

Host

is a physical server on which the virtual machines run. Alternatively, host is also called hypervisor. Both RHEL Virtualization Hypervisors and RHEL hosts interact with the rest of the virtualized environment in the same way.

Template

The templates have the ability to create virtual machines quickly and conveniently. To create a template we need a vm to copy its configuration, its networks and content of its disks.

The templates have a specific configuration and unique content on the disks. Once the template is created the content of the disks is immutable and RHV does not allow to add or remove disks. However, it is possible to modify, add or modify the networks attached to the template.

Storage Domain

Storage Domains are distinct storage subsystems used to host different kinds of information.

Two Storage Domains are used by RHV:

The Data Domain

stores virtual hard disks of VMs and templates in a Data Center. Data Domains are exclusive to one Data Center.

Data Domains can be backed by different storage attachment technologies, such as NFS, Fibre Channel, FCoE, GlusterFS, Ceph, iSCSI, and any (local) POSIX-compliant file system.

The ISO Domain

hosts images of media such as CDs and DVDs to deploy software on VMs. There can only be one ISO Domain in a Data Center, an ISO Domain can be shared among Data Centers, and NFS is the only available backing store for this type of storage domain.

Data Warehouse

RHV employs a database of historical data where all the management and auditing data is stored. This function is provided by the ovirt_engine_history service. It makes use of the PostgreSQL database for storing its data.

Networking

RHV allows the definition of different logical networks to isolate traffic types and paths. These networks are created, maintained, and destroyed by the RHV Manager, which also handles VLANs, routing, and firewalling.

Usually, there will be several networks in use in a RHV Datacenter. Some pre-defined network types are available to segregate different types of traffic: A management network which should be used exclusively by RHV management communications, VM networks for use by the virtual machines, storage networks for example for iSCSI or NFS traffic, and storage migration networks.

Networks for dedicated purposes can be created as needed, and they can be bound to specific network hardware (and VLANs) available on the virtualization hosts.

Red Hat Virtualization APIs

RHV provides different APIs to access its functionality:

The Bacula Enterprise Red Hat Virtualization Plugin is based on the Java SDK 4.3

Connection Modes

RHV allows 2 different authentication schemes:

  • OAuth Authentication

  • HTTP Basic Authentication

The plugin supports both connection and authentication modes.

More information

The information of this chapter is based upon the official RHEL Documentation available in the following links:

See also

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