Choosing a Datacenter compute model

Compute models refer to infrastructures with which the IT department or datacenter chooses to render ,deliver, or deploy a particular service.
 Certain services/applications may be right candidates for central management or central distribution while others are just better managed locally,also existent in modern computing  is a hybrid of the two. Needless to say the various subtypes of these models.

MODERN COMPUTE MODELS

1.TERMINAL SERVERS
In this model,the client is merely a display and input device. All computation is
done centrally on the server, and all data is stored in a data center.
Nothing is executed or persistent on the client. Usually, Remote
Display Protocol (RDP) or Independent Computing Architecture*
(ICA*) is used to push an image of the server-based application
to a terminal viewer on the client.

2.VIRTUAL DESKTOP INFRASTRUCTURE
As with Terminal Services, all computation and storage are centralized,
with application images pushed over the network to the client
via Remote Display Protocol (RDP) or other display protocols. The
major difference is that VDI can offer each user their own complete
virtual machine and customized desktop, including the OS, applications,
and settings.

3.BLADE PCs
Much like server  blades,Blade PCs repartition the PC, leaving basic display, keyboard, and
mouse functions on the client, and putting the processor, chipset,
and graphics silicon on a small card (blade) mounted in a rack on a
central unit. OS, application, and data storage are centralized in a
storage array.
Unlike server blades, PC blades are built from standard desktop or
mobile processors and chipsets. The central unit, which supports many
individual blades, is secured in a data center or other IT-controlled
space. In some cases, remote display and I/O is handled by dedicated,
proprietary connections rather than using RDP over the data network.



4.OS Image Streaming or Remote OS Boot
At startup, the client is essentially “bare metal,” with no OS Image
installed locally. The OS Image is streamed to the client over the
network, where it executes locally using the client’s own CPU and
graphics. Application data is stored in a data center. The client is
usually a PC with no hard drive, which uses RAM exclusively

 5.APPLICATION VIRTUALIZATION
The client OS is locally installed, but applications are streamed
on demand from the server to the client, where they are
executed locally.
Although the terms “streaming” and “application virtualization” are
often used interchangeably, they are not the same thing. Streaming
refers to the delivery model of sending the software over the
network for execution on the client. Streamed software can be
installed in the client OS locally or, in most cases, it is virtualized.

FACTORS TO CONSIDER IN SELECTING THE RIGHT MODEL
 The factors listed below should be quantified per model, making trade-offs where necessary and contrasted to determine the optimal model for every unique service need.

Performance
Security
Manageability
Mobility
Disaster recovery
Infrastructure cost
User customization
Remote network access
Remote access

Reference: Principled technologies white paper titled "Understanding alternative compute models"