In Azure Virtual Desktop (AVD), Session Hosts and Normal Hosts (also known as Virtual Machines) are two different types of virtual machines (VMs) used for different purposes within a virtual desktop infrastructure (VDI) environment. Let’s explore the distinction between them:
1. Session Hosts in Azure Virtual Desktop (AVD)
- Definition: A Session Host is a virtual machine that runs the actual desktop or application session for a user in Azure Virtual Desktop. These VMs are used to host multiple user sessions on the same operating system instance. Users log into these session hosts to interact with their desktop environment or specific applications.
- Role in AVD:
- The Session Host is the machine that users connect to when they launch their virtual desktop or remote applications.
- Multiple users can share a session host, with each having their isolated session. This is known as a multi-session model.
- It is typically configured with a standard Windows Server OS (like Windows Server 2019/2022) or a Windows 10/11 multi-session image. The latter is a Windows 10 or 11 image specifically configured to allow multiple simultaneous users.
- Session Hosts typically provide access to shared applications or full desktops.
- These VMs can be scaled horizontally (more session hosts can be added) to accommodate increasing user demand.
- Key Features:
- Multi-Session Support: AVD allows multiple users to log into the same session host at the same time, making it cost-effective for many scenarios.
- Resource Sharing: Session hosts share the resources (CPU, memory, disk space) between users, so resource allocation and optimization are critical for performance.
- Customizable: You can configure session hosts with apps, policies, and other settings to tailor the experience for users.
2. Normal Hosts (Virtual Machines)
- Definition: A Normal Host (more commonly referred to as a Virtual Machine (VM) in Azure) is a standard virtual machine used in a variety of roles, such as running applications, databases, or even isolated virtual desktops. These VMs are typically dedicated to a single user or application, unlike session hosts, which are designed to be shared.
- Role in AVD:
- These virtual machines are used in environments where one user requires a dedicated, persistent virtual machine (for instance, for developers, IT admins, or certain high-performance needs).
- Normal hosts are often used for Personal Desktops or Persistent Desktops, where each user has a dedicated VM that preserves their settings, apps, and files across sessions.
- These VMs may use Windows 10/11, Windows Server, or Linux operating systems, depending on the requirement.
- Key Features:
- Single User Access: Unlike session hosts, where multiple users can share the same machine, normal hosts are typically dedicated to one user.
- Persistent Storage: Normal hosts often maintain state across user sessions (e.g., desktop configuration, installed apps, files), which is important for persistent desktop environments.
- Customization: Since each normal host is dedicated to a user, they can be highly customized to meet that user’s specific needs, including custom applications, settings, and storage.
Comparison Between Session Hosts and Normal Hosts in AVD
| Feature | Session Hosts | Normal Hosts |
|---|---|---|
| User Access | Shared access by multiple users (multi-session) | Dedicated to a single user (persistent) |
| Operating System | Windows 10/11 Multi-Session or Windows Server | Windows 10/11 or Windows Server (or Linux) |
| Use Case | Shared desktops and apps for multiple users | Personal, persistent desktops for one user |
| Resource Allocation | Resources are shared among users | Resources are dedicated to a single user |
| Persistence | Non-persistent or can be configured to save user data | Persistent with saved settings, data, and apps |
| Cost Efficiency | More cost-efficient, as many users share the same VM | More expensive as each VM is dedicated to a user |
Which to Choose?
- Session Hosts are ideal for environments where many users need access to shared desktop environments or applications. It is a cost-effective solution for scenarios such as virtualized desktops for general office workers, remote applications for large teams, etc.
- Normal Hosts (or personal desktops) are better suited for scenarios where a user requires a dedicated virtual machine, such as for developers, remote workers needing specific apps or configurations, or when a persistent desktop experience is needed.
In summary:
- Session Hosts are designed for multi-session and shared access scenarios in Azure Virtual Desktop.
- Normal Hosts (VMs) are typically used for single-user dedicated environments, where each user has their own isolated virtual machine.