Scientists have always tried to reduce chaos through the application of theories which attempted to explain, and predict, what had, until then, been inexplicable and unpredictable.
Although natural science and philosophy are direct predecessors to today’s information sciences, here at DNSTM we feel that an appreciation for philosophy is useless if it doesn’t influence the work one does, for the better.
Our understanding of systems administration is best described by comparing the entire job description to a layer cake. Each ‘layer’ in the cake is dependent upon the layers beneath it, so a good administrator insures that each of these layers remains in good working order.
There are always at least four layers to be dealt with; power, hardware, operating system and application. They must be dealt with in exactly this order, because each ‘layer’ is utterly dependent upon the layer beneath it and cannot exist unless the preceeding layers are in good working order. Like this:
- operating system
The first layer of the ‘cake’ is your power grid. Less experienced administrators ignore it, or leave it until last, but the truth is that everything depends upon a continuous and reliable stream of power. Ignore it at your peril.
The second layer of the ‘cake’ is the hardware. Once you have power, this leads directly to the computers being unboxed and plugged in. They will need to be installed and configured – BIOS boot device order may need to be changed, for instance. Peripheral devices will need to be installed.
The third layer of the ‘cake’ is the operating system. This needs to be installed, patches need to be applied, and the operating system needs to be configured.
The fourth, and last layer, is the application. For instance, in the case of a simple standalone desktop PC connected to a laser printer, the application might be Excel, or Microsoft Word. It, too, needs to be installed and configured. For example:
- Microsoft Windows
There can actually be many more layers – for instance, in the case of a Linux-based LAMP server, layer four is the MySQL database … layer five is the PHP- or Perl-based middleware … and layer six is the Apache server. IE,
- Apache web server
- PHP middleware
- MySQL RDBMS
This abstracted model of a computer system grows more interesting when one realizes that this model maps out inherent dependencies so well that it can also be used as a diagnostic tool, to insure an orderly progression towards the solution of any possible problem one might, as the administrator, encounter, without repeating any diagnostic steps, unnecessarily; an important factor, when computers are down, and downtime is costing money.
Above we suggested that four layers would be sufficient to describe the simplest case; a standalone desktop PC. This is technically true but in the real world most computers are networked; this introduces a fifth layer, which we think of as Layer Zero.
We have found this layer-based model provides the sort of rigor that is required when analyzing, diagnosing, explaining, documenting and supporting the sort of complex, one-of-a-kind problems that DNSTM staff are frequently called upon to solve.
Our approach to problem-solving is our single most valuable asset; and it is this which we offer to you, our customer.