Hello, I'm an expert in cloud computing and virtualization technologies. I'm here to help you understand the hypervisor used in Amazon Web Services (AWS) and its role in the infrastructure.
Hypervisors are a critical component in cloud computing. They create and manage virtual machines (VMs), allowing multiple operating systems to run concurrently on a single physical server. AWS, being one of the leading cloud service providers, utilizes a hypervisor to offer its wide range of services to customers.
**The hypervisor used in AWS is Nitro, not Xen.** This is a common misconception due to the historical use of Xen in the early days of AWS. However, AWS has since developed its own hypervisor called Nitro, which is a dedicated hardware and software stack that offloads most of the virtualization tasks from the host processor to purpose-built hardware.
### Nitro Hypervisor
The Nitro system is a virtualization technology that AWS designed to provide a more secure and flexible environment for their cloud services. Here's a breakdown of its key features and benefits:

1. Security: Nitro includes dedicated hardware components that are isolated from the host EC2 instance. This isolation ensures that even if an EC2 instance is compromised, the underlying hardware and other instances remain secure.

2. Performance: By offloading tasks like encryption, networking, and storage to dedicated hardware, Nitro allows the host CPU to focus on running the guest operating system, which can lead to better performance.

3. Scalability: Nitro allows AWS to scale resources quickly and efficiently. Customers can choose from a wide range of instance types, each optimized for different workloads.

4. Flexibility: With Nitro, AWS can offer a variety of instance types that support different operating systems and configurations. This flexibility allows customers to choose the best instance type for their specific needs.

5. Integration with AWS Services: Nitro is tightly integrated with other AWS services, making it easier to manage and deploy resources across the AWS ecosystem.
### Xen Hypervisor
While AWS has moved on from Xen, it's worth noting that Xen was a popular choice for virtualization in the early days of cloud computing. Xen offers two types of virtualization:
- HVM (Hardware Virtual Machine): This is a full virtualization method where the guest OS thinks it's running on real hardware. It requires hardware support for virtualization, like Intel VT or AMD-V.
- PV (Paravirtualization): This method requires the guest OS to be aware that it's running in a virtualized environment. It can offer better performance than HVM in some cases but requires modifications to the guest OS.

### Transition from Xen to Nitro
AWS's transition from Xen to Nitro represents a shift towards a more secure, high-performance, and flexible virtualization solution. This transition has allowed AWS to offer a wide range of services and instance types that meet the diverse needs of their customers.

In conclusion, while Xen was used in the past, AWS now uses the Nitro hypervisor to deliver its cloud services. Nitro's design focuses on security, performance, scalability, and flexibility, making it an ideal choice for the modern cloud environment.

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The AWS AMI and the Xen hypervisor. Every AWS AMI uses the Xen hypervisor on bare metal. Xen offers two kinds of virtualization: HVM (Hardware Virtual Machine) and PV (Paravirtualization).Dec 15, 2015read more >>