Best Practices




Zero-Client Computing: Is it Right for Your Library?

Librarica

Back in the ‘60s and ‘70s when a computer engulfed a whole room or even a whole building, computer access at the desktop was possible only through text-only “dumb terminals.” Then, the ‘80s brought about the reality of the desktop computer for the masses. In recent years, there is again a movement toward centralizing computing power. Is this just another fad or is this technology one that your library should investigate? Here, we will explore the advantages and disadvantages of this technology and other considerations involved in deploying it.

First, let us differentiate between the terms “zero client” and “thin client.” These terms are used interchangeably by some vendors, while other vendors seem to prefer to use the term zero client, maybe because it sounds more minimal and therefore better. On top of that, the definitions seem to be changing with time; we present the most current here.

zero client (n.) 1. a small form factor hardware device that has no internal operating system and just enough processing capability to operate the keyboard, mouse and display. A zero client typically connects to a server via Ethernet or USB. 2. a work station that consists of no hardware other than the actual user interface devices – the keyboard, mouse and display connect directly to a server, which possesses connections for the user interface devices from multiple work stations.

thin client (n.) a small form factor “diskless” computer with a stand-alone operating system. The operating system image is typically loaded from non-volatile RAM or from a server through the network. A modest amount of persistent storage may be available on non-volatile RAM.

We now discuss advantages and disadvantages of zero client technology versus existing desktop computer technology.

The Advantages:

  • Lower power consumption Assuming that the monitor is present in both situations, a zero client uses drastically less power than a desktop: 5W or less versus 80W to 150W.
  • Smaller size Many zero clients are small enough to be mounted on the back side of a monitor. There is even talk among vendors of embedding zero client hardware within the monitor in the future.
  • Lower cost Even five years ago, many zero client solutions offered a dubious cost advantage over a desktop computer. This is changing, and zero client hardware can now be had for under $100 per work station. However, keep in mind that you must still purchase operating system client access licenses for each work station.
  • More convenient to deploy and maintain software All software is installed and maintained on the server, as opposed to individually on each work station.
  • Longer usable lifetime Since virtually all of the processing is performed on the server, the server is the only component that really needs to keep pace with the hardware requirements of the latest and greatest operating system. Also, zero clients do not have moving parts like hard drives and fans, which eventually fail in a desktop computer.

The Disadvantages:

  • Single point of failure Although reliability in modern server hardware is light years beyond that of the ‘60s and ‘70s, this possibility still exists. And when the server goes down, all of its clients go down with it.
  • CPU-intensive applications can lower performance for all clients Multimedia and other graphics- or computationally-intensive applications are still a challenge for this technology. This is the most important consideration when calculating the client load that a given server can handle.
  • Specialized IT experience required In actuality, each user is logged on to the server interactively. This means that your IT staff must really lock down the server to prevent one user from performing an action (innocently or otherwise) that will affect all of the other users.

Client load calculations are critical in determining performance and calculating the viability of the proposed system from a cost standpoint. A good rule of thumb is ten work stations per well-appointed server, but the number could go as low as five for cases of heavy use of CPU-intensive applications. The recommended approach is to evaluate the performance of the proposed system in a testbed before contemplating a large-scale deployment.

In the enterprise, zero clients are connected to a host running a server operating system. Microsoft has recently released a special version of their server product, dubbed Windows MultiPoint Server, which is optimized for zero client deployment in enterprise environments. This operating system supports work stations consisting of both types of zero clients: those with directly-connected user interface devices as well as with zero client hardware. A client access license (CAL) is required for each work station and for the server itself if it is used as a work station.

Zero client technology can offer a number of advantages for managing and operating the computers in a library or computer lab, if the technical challenges are managed effectively.

Librarica LLC offers solutions for the management of printers and wired/wireless computers in public and academic libraries and computer labs. Librarica’s CASSIE System supports zero clients and thin clients served through Windows Terminal Services, as well as traditional desktop computers.