Imagine that I have multiple datacenters and multiple types of network and
multiple hypervisors. If I want to allow non-IT people to deploy virtual machines
and services, I need to abstract all that underlying fabric infrastructure from
them. The user needs to be able to say (or request through a self-service
interface), “I want an instance of this service in Datacenter A and B, and it should
connect to the development and backup networks on a silver tier of storage.”
Behind the scenes, the private cloud infrastructure works out that for the
development network in Datacenter A, the network adapter needs an IP address
in a certain subnet connected to a specific VLAN and some other subnet and
VLAN in Datacenter B. The infrastructure works out that silver-tier storage in
Datacenter A means using the NetApp SAN and only certain LUNs, while in
Datacenter B the EMC SAN is used with other specific LUNs. The user gets the
service and connectivity needed with zero knowledge of the infrastructure, which
is exactly as it should be.Self-service by the user for the provisioning of these services is a great way to think of
the difference between virtualization and the private cloud. Let me walk you through
the most basic case: creating a new virtual machine for a user. Provisioning virtual
machines in a virtual world goes like this (see Figure 9. 1 ):
1. The user makes a request to the IT department. This could be a phone call, an
email, or a help-desk request.
2. The IT department gets the request and may perform some validation, such as
checking with a manager to ensure that the request is approved.
3. IT launches their virtualization management tool and creates a virtual machine
from a template.
4. IT contacts the user and provides the IP address of the VM.