What Is VDI And How Does It Work?

VDI (Virtual Desktop Infrastructure) is a technology used to create a virtualized desktop environment on remote server setup. VDI segments the servers into various virtual desktops that the users can access remotely through their devices. These virtual desktops are hosted on Virtual Machines (VM) that are controlled through management software.

For instance, as an owner of an accounting firm, imagine the inconvenience you face while installing and configuring all those desktop PCs and the maintenance and upgrade requirements that keep coming with time.

With VDI, as the desktops are virtual, you can access them even with a thin client.

As far as the users are concerned, VDI gives you the freedom to access your desktop from anywhere at any time through a VDI client software.

VDI can be classified as persistent and non-persistent. Persistent VDI is customized for a personal user, and the user can log in to the same desktop each time. Non-persistent VDI consists of desktops that revert to their initial state after the user logs out.

In this article, we will discuss the components involved in VDI technology and its working. Let us first talk about some of the benefits that the VDI technology entails.

Benefits of VDI

1. Access

The most distinguishing feature of VDI is remote access. Traditional desktops can be viewed as connected (or, one can say ‘restricted’) to a single system. As soon as you are away from the system, you could not access your desktop anymore. With VDI, you can access your desktop from anywhere, day or night.

2. Security

Another vital aspect of VDI is security. Conventionally, your Operating System, Applications, and data are all stored on your local hardware like laptops or PCs. In case the computer is stolen or damaged, all the data is lost. You also have to buy a new laptop and start all over again with OS installation.

With VDI, as remote data centers store the data with high-level redundancy, you do not need to worry about data loss. Even if you lose the device, you can access your desktop from any other device.

3. Device Portability

VDI technology enables you to access your desktop from various devices. As in the case of VDI, the desktop is not bound to the hardware; it can be accessed from multiple devices. You can use mobile, laptops, tablets, or thin clients to view your desktop.

Easy Desktop Provisioning – Since with VDI, you don’t have to configure each system manually, it very easy to provision the desktops in VDI. The virtual desktops can be provisioned almost instantaneously as the settings have to be mirrored from a desktop image.

4. Data Center Facilities

When you are availing VDI from a cloud service provider, the desktops are hosted on servers situated in high-performance data centers. You get all the facilities and features associated with the data center, namely advanced security, high-end infrastructure, and disaster recovery plan, among others.

5. Cost Reduction

By availing VDI services from a cloud provider, you eliminate the cost of hardware. You can access your desktop from any device and can use the most outdated equipment in your office. A thin client, mobile, or tablet can also be used for the same purpose.

VDI Basic Components

The functioning of VDI consists mainly of two parts- Hypervisor and Connection Broker. But before we move on to these aspects, let us first discuss in brief about virtualization.

1. Virtualization

Virtualization is the technology that divides the system architecture into different layers. Before virtualization, the hardware was bound to the operating system (OS) at the time of installation. Thus, in the case of a hardware failure, the OS also crashed, and you would lose all the data.

Through virtualization, the OS and the underlying hardware are separated by a software called hypervisor. You can install multiple operating systems on a hypervisor installed server.

2. Hypervisor

The hypervisor is software that separates the operating system from the underlying hardware. The hypervisor creates a virtualized environment in which the equipment can be divided into multiple virtual machines (VMs). Each virtual machine can have a unique configuration, OS, and applications.

In VDI, the hypervisor creates desktop instances in these VMs. Each desktop instance can act as a separate desktop and can be provisioned to the users.
The High Availability (HA) function in the hypervisor also lets it connect to multiple servers. Hence, even if a physical server fails, your desktop instance is moved to another server almost instantaneously.

3. Connection Broker

Connection broker is a software program that connects the users to the desktop instances. It is also responsible for the authentication of the users and sending them to their desktop instances.

The connection broker also keeps track of active and inactive desktops. When a user sends a request to connect to a desktop, it provides the user with an idle desktop instance. When a user disconnects desktop, it updates the status to inactive.

4. Desktop Pools

Desktops pools are a group of similar desktops that can be configured according to a specific function. For instance, departments like accounting and IT in an office might use desktops with different applications and configurations. The accounting department may need applications like Sage or QuickBooks, which may not be required for IT.
You can create a desktop pool for these departments with a similar configuration.

5. Application Virtualization

Application Virtualization is the technology used to create a virtualized application image and replicate it to all the virtual desktops in a desktop pool. It makes application deployment easy and hassle-free.

VMware ThinApp is an example of that. It creates an executable file of the application by capturing pre and post images of the system before and after installation of the software. You can use this file in any order without going through the installation process repeatedly.

How VDI works?

Image: VDI Working Concept

• When the user logs in to their desktop from the client software, the request is accepted by the connection broker after authentication. The connection broker then analyzes the application and sends the user to their desktop in the desktop pool.
• The hypervisor installed on the servers creates multiple VMs on which the virtual desktop is hosted. The High Availability feature in hypervisors can combine the resources of various servers, and the virtual desktops can be migrated to another server if needed.
• The admin can turn the virtual desktop off when the user is not using it. This way, you can accommodate more users than the actual capacity of the server. For instance, on a server with 500 GB RAM, you can create 600 Virtual desktops with 1 GB RAM, assuming that not all 600 users will use the desktop at the same time.
• The desktop image is mirrored from a master desktop to all the other desktops. It is called cloning. The cloning can be full or linked.
• In Linked cloning, the virtual disk of the master desktop is linked to all other desktops. It saves the disk space of the server. The data of all the users are collected separately. However, the cloned desktops have to be linked to master desktops at all times.
• In Full cloning, the cloned desktops are not linked to master and function as independent desktops. Hence, all the desktops use separate disk space.
• The VDI management software like VMware View Manager can be used to create desktop pools. The admin user can manage the desktop pools, provision new desktops, create new repositories, and set up policies.

Posted by Sharad Acharya