A small explanation about an AHV host looks inside an AHV host and shows some details.
First and foremost, what is AHV?
Nutanix AHV (Acropolis Hypervisor) is a native hypervisor integrated into the Nutanix Enterprise Cloud Platform. It is designed to run virtual machines (VMs) in a simplified and efficient manner. AHV is built for ease of use, offering features like one-click VM management, seamless scaling, and built-in security. It leverages the underlying Nutanix architecture, enabling users to utilize features like data locality, high availability, and disaster recovery without deploying third-party hypervisors. AHV supports various workloads, making it a versatile choice for organizations looking to optimize their virtualization environments.
During the AHV host deployment, a Controller Virtual Machine (CVM) is deployed together.
Nutanix CVM (Controller Virtual Machine) is a virtual appliance that runs on each node in a Nutanix cluster. It plays a critical role in managing storage and virtualization functions within the Nutanix architecture. The CVM handles tasks such as data replication, deduplication, compression, and storage management, enabling features like data locality and high availability. Each CVM also runs the Nutanix Distributed File System (NDFS), which provides the underlying storage services for virtual machines and applications. Essentially, the CVM acts as the brain of the Nutanix environment, ensuring efficient data operations and resource management across the cluster.
Basic AHV Architecture
As we learned, a CVM is deployed on each AHV host, and all disks are presented using PCI passthrough. This means the CVM is responsible for managing all disks directly (bypassing the AHV), which is an important fundamental in a Nutanix cluster.
In the following picture, we can see the AHV architecture. Look at the Controller VM (CMV). It accesses the disks directly, bypassing the AHV layer, and handles all I/O operations in the AHV host:
All GuestOS virtual machines (or User VMs) access the storage layer through the Controller VM (CVM).
AHV is based on CentOS KVM. Full hardware virtualization is used for guest VMs (HVM).
Essential KVM Architecture inside an AHV host
Within KVM, there are a few main components:
— KVM-kmod: KVM kernel module that enables the virtualization feature (basically);
— Libvirtd: An API, daemon, and management tool for managing KVM and QEMU. Communication between AOS and KVM / QEMU occurs through libvirtd.
— Qemu-kvm: A machine emulator and virtualizer that runs in userspace for every Virtual Machine (domain). AHV is used for hardware-assisted virtualization, and VMs run as Guest VMs.
In the following picture, we can see all the components and how each one can interact among them:
AHV virtualization is one of the core components of the Nutanix Solution:
Cluster Concept in a Nutanix Environment
We can group several AHV hosts and create a logical ” Cluster ” structure. A cluster is like a “pool” of CPU, RAM, Disk, and Network resources. One or more Virtual Machines (VMs) can run over the cluster using these shared resources. In this context, the AHV hypervisors play an essential role because it is responsible for providing computing resources to run each VM.
If one cluster node fails, a virtual machine running on it can be restarted automatically elsewhere. Even though a VM is restarted, this process is taken automatically, and the administrator did not do it manually (the cluster process can detect the host’s failure and take action on it).
In the following picture, “Node” is an AHV representation. Each AHV has the Controller VM (CVM) and one or more guest VMs running on it:
Key Capabilities of Nutanix AHV
We will show some key capabilities of Nutanix AHV hypervisor:
- VM Templates
- Memory Overcommit
- VM Affinity Policies
- Virtual Trust Platform Module (vTPM)
- Live Migrations
- Generation ID
- Advanced Processor Compatibility
- Automatic Cluster Selection
- Acropolis Dynamic Scheduler (ADS)
- Powerful networking with Open Virtual Switch (OVS)
To Wrapping This Up
As we can see, the Nutanix AHV is an optimized hypervisor that offers interesting resources for an HCI environment. I encourage you to create a Nutanix cluster in a lab environment using a Nutanix Community Edition (CE) to see how powerful a Nutanix AHV-based cluster is.
In the following link, you can find more details of AHV:
https://www.nutanixbible.com/5-book-of-ahv.html
Additionally, we have written some Nutanix articles. You can access them using the following link: