Nutanix Acropolis Hypervisor a.k.a AHV

  • 26 November 2020
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Nutanix AHV is a bare metal Type-1 hypervisor developed by Nutanix. Nutanix AHV can be directly installed on any Nutanix certified OEM hardware server i.e SuperMicro NX, IBM CS , Lenovo HX , HPE ProLiant, Cisco UCS, Dell XC and many more being added along the way.

AHV is built upon the CentOS KVM foundation and extends its base functionality to include features like HA and live migration, etc. Full hardware virtualization is used for guest VMs (HVM).

In AHV deployments, the Controller VM (CVM) runs as a VM and disks are presented using PCI pass-through.  This allows the full PCI controller (and attached devices) to be passed through directly to the CVM and bypass the hypervisor. 

AHV does not leverage a traditional storage stack like ESXi or Hyper-V. All disk(s) are passed to the VM(s) as raw SCSI block devices. This keeps the I/O path lightweight and optimized.

KVM Architecture:

Within KVM there are a few main components:

  • KVM-kmod

    • KVM kernel module

  • 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).  In AHV it is used for hardware-assisted virtualization and VMs run as HVMs.

The following figure shows the relationship between the various components:

KVM Component Relationship

 

 

Configuration Maximums and Scalability:

The following configuration maximums and scalability limits are applicable:

  • Maximum cluster size: N/A – same as Nutanix cluster size

  • Maximum vCPUs per VM: Number of physical cores per host

  • Maximum memory per VM: Min of 4TB or available physical node memory

  • Maximum virtual disk size: 9EB* (Exabyte)

  • Maximum VMs per host: N/A – Limited by memory

  • Maximum VMs per cluster: N/A – Limited by memory

*AHV does not have a traditional storage stack like ESXi / Hyper-V; all disks are passed to the VM(s) as raw SCSI block devices. This means the maximum virtual disk size is limited by the maximum DSF vDisk size (9 Exabytes).

 

 

Nutanix AHV – Virtual Network:

AHV leverages Open vSwitch (OVS) for all VM networking.  VM networking is configured through Prism / ACLI and each VM NIC is connected into a tap interface

Nutanix AHV hypervisor embedded the Open Virtual Switch OVS virtual networking stack to provide the flexibility to use the following network feature:

  1. Teaming Modes 
    • ​​​​​​​Active-Backup,
    • Balance-TCP / LACP
    • Balance-SLB 
  2. QOS (Quality of Service) for Traffic Monitoring and shaping
  3. Trunk Mode and Access Mode for Guest VMs
  4. VLAN Tagging 

Some useful links:

  1. Nutanix Bible - https://nutanixbible.com/

  2. AHV Networking - https://portal.nutanix.com/page/documents/solutions/details?targetId=BP-2071-AHV-Networking:BP-2071-AHV-Networking

  3. Download AHV - https://portal.nutanix.com/page/downloads?product=ahv

  4. AHV administration Guide - https://portal.nutanix.com/page/documents/details?targetId=AHV-Admin-Guide-v5_17:AHV-Admin-Guide-v5_17


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