Server roles

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Classes of servers

These are the main classes of servers that we maintain with their descriptions. This page used to list machines themselves but as this is an ever changing list it has been omitted. If you need to find host info go to

Web Servers

This is the main class of server we have. In many respects all servers we host are in this class as they all have a web server installed on them. This is typically an Apache HTTPd server.

Web Proxy Servers

These servers commonly have a web proxy caching engine such as Squid and/or a HTTP based load balancer. These server rarely provide any content themselves and are used to provide a transparent layer for multsite or High Availability services. Most Web Servers listed above are also considered in this group due to the mixed mode nature of Virtual Hosting.

Database Servers

Database servers are containers of… well data. Again a few servers hold their own database installations for specific application requirements. The software that is primarily used for databases (or our RDBMS) are PostgreSQL and MySQL.

Application Servers

Applications servers is a bit more of a generic term for a server which provides the “backend” to a website, normally this would be a server which does a fair amount of computational data crunching to allow for faster operation of the “frontend”: the Web Server. There are a few subclasses of Application Server.

Java Application Servers

App Server for Java based applications.

Zope Application Servers

Zope App Servers which run Zope/Plone CMS applications.

CGI Application Servers

CGI based applications are ones which are called from within a Web Server process as opposed to being independent daemonised processes like Tomcat or Zope. So although the server is a Web Server too it does more work due to it’s scripted components.

Specialist Application Servers

These are applications chosen for a specific use case that run as standalone daemons. Currently we have Prolog and Cassandra which fit into this group.

Core Servers

Core Servers are those that provide backbone services which all other services rely on for their day-to-day operation. These services are things like DNS for name resolution and SMTP for email delivery to and from the hubs. Core servers can also provide the transparent services or deployment platforms, things that you don’t notice immediately when they disappear!

File Servers

File Servers are basically a bunch of disks in a box with a few daemonised services linked to a centralised authentication mechanism. They are usually the most simple and at the same time the most important.

Hypervisors (Virtual Machine Hosts)

Hypervisors are servers which have a sole purpose to host virtual machines. Some are configured in clusters (groups of servers built to act as one service). Virtual Machines hosted on these servers are not statically assigned to these servers and therefore may shift location from time to time. Hypervisors are extremely stripped down installations and normally do not provide direct access to staff or host any services.

Development Servers

Dev Servers are just that, a place where pre-deployment testing occurs. These by nature are the least stable and management of them can be quite chaotic. Do not ask me to list all the software that runs on these boxes, it’s safe to assume that all of the above is included. Under no circumstances should a service be advertised to an external client unless it has been discussed with service managers and/or system administrators. Stability of a service hosted on a Development Server cannot be guaranteed.