hardware when services are deployed that require hardware load balancing.
Initial deployment is fine, but what about maintenance, patching, and scaling? I’ll
cover other components of System Center 2016 (such as Configuration Manager,
which can simplify automated patching of both server and desktop operating
systems), but you can still use service templates. Unlike a normal virtual machine
template, which loses any relationship with a virtual machine deployed from the
template, any instances of a service deployed from a service template maintain the
relationship to the template.
Think about being scalable and elastic. Those same service templates allow a
minimum, maximum, and initial instance count of each tier of service. Let’s look at
the web tier as an example. I could configure the tier to have a minimum instance
count of 2, a maximum of 20, and an initial of 4. When load increases, the user can
access the tool and scale out the tier to a higher number, such as 10, and the backend
infrastructure automatically takes care of creating the new virtual machines, setting
up any configuration, and adding the new instances to the load balancer and any other
associated actions. When the load dies down, the user can scale in that service, and
once again the backend infrastructure will automatically delete some virtual machines
that make up that tier to the new target number and update the hardware load
balancer. I’m focusing on the user performing the scale-out and scale-in, but that
same private cloud could have monitoring in place, such as with System Center
Operations Manager; when load hits a certain point, it runs an automated process
using System Center Orchestrator that talks to System Center Virtual Machine
Manager to perform the scaling. That’s why when I talk about the private cloud and
focus on the application, it’s not just about System Center Virtual Machine Manager;
the entire System Center product plays a part in the complete private cloud solution.
This scalability and elasticity—meaning having access to resources when needed but
not using them, and allowing other services to leverage them when not needed—are
key traits of the private cloud. Many organizations charge business units for the
amount of computer resources that are used by their applications, which is why the
ability to scale is important. By running many services on a single infrastructure, you
will see high utilization of available resources, getting more bang for the
infrastructure buck.
AGNOSTIC OF THE UNDERLYING FABRIC
“Agnostic of the Underlying Fabric” can be confusing. For example, say I want to
offer services to my customers, which could be my IT department, business units
in the organization, or individual users. To those customers, I want to provide a
menu of offerings, known as a service catalog in ITIL terms. When those
customers deploy a virtual machine or service, they should not need to know
which IP address needs to be given to the virtual machine or virtual machines if
deploying a single or multitiered service. The customer should not have to say
which storage area network to use and which LUN to use.