Ten crucial server attributes

A server is a specialised machine — but it is also based on PC technology. So, what defines a server and separates it from the familiar personal-computing technology that lives either on your desk or your lap? And what is missing from the mix?

Generally speaking, a core philosophy behind server design is the notion that the machine must continue to provide a service even if an individual hardware component fails. Servers also deliver files and process information for multiple users simultaneously, so they need to be computing powerhouses.

All this data needs to get to and from users as fast as possible, so expect lots of high-speed network ports. And because they are not machines you sit in front of all day, they need to be remotely manageable.

Finally, there is one other characteristic that servers have all possessed up until now — but that may be starting to change. (More on this later.) Here then are the most important hardware attributes a server must possess if it is to fit the bill — and at the end, we have added are some items you should not expect to see.

Crucial attribute 1: Processors
At the heart of the server is the processor — or, more usually, these days, at least a pair of processors. If a server is doing anything more than just file-serving, then computing power is likely to be in demand. So this Dell T710 houses a pair of brand-new Intel Core i7 Xeon processors, using 45nm processor microarchitecture — code-named Nehalem.

Crucial attribute 2: Memory
Without memory, a computer is useless: our test server contains 12GB of PC8500 1066MHz DDR3 memory in the form of six 2GB DIMMs. That is enough to run a modern hypervisor such as VMware's ESX and up to around eight to 10 virtual machines — which is increasingly what even low-end servers are being asked to handle.

Crucial attribute 3: Storage
Storage is a crucial part of the server, if only because the server needs an operating system from which to boot. While in many cases, servers boot from the network, local storage for the operating system and other data that needs to be held locally is typical. In this case, we have eight 10,000rpm SAS drives of 146GB each, configured for Raid 5 which helps protect against the consequences of a drive failure, and provides around 1TB of storage.

Crucial attribute 4: Network
The data I/O channel is often the server's bottleneck but this machine houses four 1Gbps load-balancing Ethernet ports, helping to speed the flow of data and provide redundancy against hardware failure. Because of the growth of virtualisation technology, I/O is in greater demand because each virtual machine could be serving dozens of users' requests for information.

Crucial attribute 5: Power
The server draws power via a mains cable but in a typical configuration it will house a pair of power supply units (PSU). This means that when a PSU fails — and moving parts such as the PSU fan along with hard disks are the server's most failure-prone components — the machine continues working. This server's 1100W hot-plug PSU slides out for easy online replacement.

Crucial attribute 6: Cooling
Venting excess heat from high-powered processors is crucial. This server contains four fans but can continue to run on two, should they fail. Like the power supply unit, the fans can be removed while the server is running to provide continuous service. For photographic purposes, we have removed the plastic ducting that helps ensure the cooling air flows over the CPUs and memory.

Crucial attribute 7: Remote management
Servers tend to live in places such as datacentres or, in smaller offices, dedicated locked rooms. They are not easily accessible yet admins need to be able to manage them remotely, at any time.

That is why this server is equipped with a remote-management port and a management application on a flash SD card. The management port allows admins to manage the server using an out-of-band network, which does not affect production network traffic.

Crucial attribute 8: Diagnostics
When you are in the presence of the hardware, it is useful to be able to grab a quick snapshot of the server's state to help with problem solving. This server's front bezel includes a one-line LCD that provides system information, such as system health monitoring, alerts and control of basic management configuration. It also allows admins to view a power meter and ambient temperature.

Crucial attribute 9: Power security
The basic IEC mains cable includes a plug that simply pushes into a socket on the back of the machine. But it is not a secure design and it is all too easy to pull the plug out by accident, perhaps when moving the server, or if the cable has been untidily routed. This simple Velcro cable security strip can prevent that happening.

Crucial attribute 10: Noise
The final issue is noise. Servers are still pretty noisy and this machine, though a little quieter than many, still makes more racket than would be acceptable in an office as a result of its multiple fans. But quieter servers are the future: noise results from wasted energy, and energy conservation is high on the agenda of all system and component designers.

Four things you do not need in a server:

1. Graphics
There is no need for expensive, power-sapping graphics cards in a server. The most complex graphics task for a server is a graphical user interface that is rarely used. If it is running Linux, you are more likely to do that remotely using SSH, so why waste CPU and memory on graphics?

2. Audio
Audio is unnecessary on a server because most of the time there is no-one there to listen, and the audio circuitry and its associated software are just additional points of failure.

3. Keyboard and mouse
You do not need human input devices (HID) on a server 99 percent of the time. That is not just because it is not being used interactively, but also because, on those occasions when you do need a keyboard and mouse, you can do so using a KVM device that transports the HID signals to your desk.

4. Windows licence
In fact, the machine featured in most of these pictures came with a temporary Windows licence, but you do not need one. Instead, download a 64-bit version of Ubuntu server and you will have a server that works without hefty licensing fees. Alternatively, VMware's ESX hypervisor is downloadable free and provides a tried and trusted platform for virtualisation.