2.2. Computer systems: environments

During the process of installing some GNU/Linux distributions, we often find that we are asked about the type of environment or tasks our system will be dedicated to, which often allows us to choose a sub-set of software that will be installed for us by default, because it is the most suited to the contemplated job. We will often be asked if the system will be used as a:

  1. Workstation: this type of system usually incorporates particular applications that will be used most frequently. The system is basically dedicated to running these applications and a small set of network services.

  2. Server: basically it integrates most network services or, in any case, a particular service, which will be the system's main service.

  3. Dedicated calculation unit: calculation-intensive applications, renders, scientific applications, CAD graphics etc.

  4. Graphics station: desktop with applications that require interaction with the user in graphic form.

We can normally set up our GNU/Linux system with one or more of these possibilities.

Important

More generally, if we had to separate the work environments [Mor03] where a GNU/Linux system can be used, we could identify three main types of environments: workstation, server and desktop .

We could also include another type of systems, which we will generically call embedded devices or small mobile systems like a PDA, mobile telephone, portable video console etc. GNU/Linux also offers support for these devices, with smaller personalised kernels for them.

Example 2-1. Note

GNU/Linux systems can be dedicated to server, workstation or desktop functions.

Example 2-2. Example

For example, we should mention the initial work done by the Sharp company on its Zaurus models, a PDA with advanced Linux features (there are four or five models on the market). Or also other Linux initiatives of an embedded type such as POS (point of sale) terminals. Or video consoles such as GP2X, and Sony Playstation 3 linux support. Also new smartphone/PDA platforms like Google Android, Nokia Maemo, Intel Moblin.

Regarding the three main environments, let's look at how each one of these computer systems is developed in a GNU/Linux environment:

1) A workstation type system tends to be a high performance machine used for a specific task instead of a general set of tasks. The workstation classically consisted of a high performance machine with specific hardware suited to the task that needed doing; it was usually a Sun's SPARC, IBM's RISC or Silicon Graphics machine (among others) with its variants of proprietary UNIX. These high cost machines were oriented at a clear segment of applications, whether 3D graphic design (in the case of Silicon or Sun) or databases (IBM or Sun). Nowadays, the performance of many current PCs is comparable (although not equal) to these systems and the frontier between one of these systems and a PC is no longer clear, thanks to the existence of GNU/Linux as an alternative to the proprietary UNIX versions.

2) A server type system has a specific purpose, which is to offer services to other machines on the network: it offers a clearly distinct set of characteristics or functionality from other machines. In small computer systems (for example, with less than 10 machines), there is not usually an exclusive server system, and it tends to be shared with other functionalities, for example as a desktop type machine. Medium systems (a few dozen machines) tend to have one or more machines dedicated to acting as a server, whether as an exclusive machine that centralises all services (e-mail, web etc.) or as a pair of machines dedicated to sharing the main services.

In large systems (hundreds or even thousands of machines), the load makes it necessary to have a large group of servers, with each one usually exclusively dedicated to a particular service, or even with a set of machines exclusively dedicated to one service. Moreover, if these services are provided inwards or outwards of the organisation, through access by direct clients or open to the Internet, depending on the workload to be supported, we will have to resort to SMP multicore type solutions (machines with multiple processors/code) or of the cluster type (grouping of machines that distribute a particular service's load).

The services that we may need internally (or externally) can encompass (among others) the following service categories:

a) Applications: the server can run applications and as clients we just observe their execution and interact with them. For example, it may encompass terminals services and web-run applications.

b) Files: we are offered a shared and accessible space from any point of the network where we can store/recover our files.

c) Database: centralisation of data for consultation or production by the system's applications on the network (or for other services).

d) Printing: there are sets of printers and their queues and jobs sent to them from any point of the network are managed.

e) E-mail: offers services for receiving, sending or resending incoming or outgoing mail.

f) Web: server (or servers) belonging to the organisation for internal or external use by customers.

g) Network information: for large organisations it is vital for finding the services offered or the shared resources; or users themselves, if they need services that make this localisation possible and to consult the properties of each type of object.

h) Names services: services are required to name and translate the different names by which the same resource is known.

i) Remote access services: in the case of not having direct access, we need alternative methods that allow us to interact from the outside, giving us access to the system that we want.

j) Name generation services: in naming machines, for example, there may be a highly variable number of them, or they may not always be the same ones. We need to provide methods for clearly identifying them.

k) Internet access services: many organisations have no reasons for direct access and rather have access through gateways or proxies.

l) Filtering services: security measures for filtering incorrect information or information that affects our security.

3) A desktop type machine would simply be a machine used for routine everyday computer tasks (such as our home or office PC).

Example 2-3. Example

For example, we could establish the following as common tasks (included in some of the most used GNU/Linux programs):

Example 2-4. Web sites

Open Source office suites:

http://openoffice.org

http://www.koffice.org/

http://live.gnome.org/GnomeOffice