Nova-compute services

Nova Functionality

  • The nova service is the heart of Open stack. It controls the infrastructure as a service cloud computing platform.
  • Providing a standard REST interface from which VMs can be managed
  • Supporting multiple types of Hypervisors
  • Supporting bare metal instances
  • Starting and managing instances
  • Supporting single and multi-tenancy

Nova supported Hypervisors and Bare Metal

Hypervisor   Description 
KVM  Kernel-based Virtual machine 
QEMU  Quick Emulator 
LXC  Linux Containers (through libvirt) 
UML  User Mode Linux 
Vmware  ESX/ESXi4.1 update 1 and later 
XEN  Xen,  Citirx Xen server and Xen cloud platform  
Power VM  Virtualization solution for AIX, IBMi and Linux environments on IBM power technology 

Common nova Terminology

Term  Description 
Server (instance)  A Virtual machine or bare metal system on which an OS can be installed 
Flavor  An available hardware configuration for a server. Each flavor has unique combination of disk space, memory capacity and CPU 
Image  A collection of files used to create or rebuild a server. Operators provide a number of pre-build OS images by default 
Reboot   Performs either a soft or hard reboot of a server. With a soft reboot, the OS is signaled to restart, Hard reboot is grace full shutdown for all process 
Rebuild  Remove all data on the server and replaces it with specificed image. Server ID and IP is remain same 
Resize   Converts an existing server to a different flavor 

Nova Architecture

  • Nova-api – Provides programmatic access to nova services – supports openstack compute API, Amazon EC2 API, Special Admin API.
  • Nova –compute : sets up and manage instances.
  • Nova-scheduler: determines compute nodes targets for to launch instances
  • Nova-cert : manges x509 certificates
  • Nova-novncproxy: proxy to access instances through VNC connections
  • Nova-consoleauth: authorizes console access based on user/project/role.
  • Nova-conductor: mediates interaction between nova-compute and database

Nova-Supported Hypervisors

Instance creation Status

Instance creation process

Image creation process

  • Request keystone to generate and return an auth token
  • Send API request to nova-api with token
  • Nova-API validate the token
  • Nova-API process API request
  • Nova-API makes rpc call to scheduler
  • Host-selected based on scheduling policy (nova-scheduler)
  • Start provisioning of VM on compute nodes
  • Request OS image from Glance
  • Nova-API makes rpc call to allocate network
  • Create network and associate with VM
  • Attache block volume as appropriate

Nova -scheduler

Useful commands

  • Nova service –list — to check the status of the nova componetns
  • Nova flavor-list — list available flavors
  • Nova boot —options — crating an instance
  • Nova delete – Delete an instance

Open Stack Installation Tutorial for Ubuntu……..