Thin-Client Technology

Turning PCs into not-so-dumb terminals may be one of the smartest moves you can make when it comes to planning for disaster recovery. There are

many advantages to this type of environment, known as thin-client or server-based computing, including lower hardware costs and easier client

management. And its built-in facility for disaster recovery can make it an invaluable tool for minimizing employee downtime when your network and its

PCs and workstations become unavailable.

With a thin-client system, the client sends keystrokes and mouse movements to the server over the network or dial-up connection, and the server

sends back changes in the display. Any PC can be a client, but because very little processing is performed at the desktop, businesses can also use

low-cost terminals that have no moving parts (no hard drive) and a generally small amount of memory (RAM).

Since each client is just a terminal, all data and settings—and even the applications—are on the server. To back up everything for all the users, you

need only back up the server. And for disaster recovery, backups are easier and more centralized, making it easier to take your backups off-site.

Imagine a worst-case systems disaster in which your clients and servers are lost. You must restore your backups on other servers. Ideally, you

should move to a mirrored server setup in which you can use the same server and domain names; in this case, your clients should be able to connect

and continue as if nothing had happened. Not many companies want to maintain an expensive set of parallel servers. If you have to restore your

backups to a different server configuration, you may need to write some new log-on scripts, but because all the computing is server-based, you

should be able to make the changes easily.

The two leading thin-client platforms are Citrix MetaFrame (MetaFrame/Workgroups 1.8 for Windows 2000 Server, for 5 users, $2,000 street; for 15

users, $5,000; www.citrix.com) and Microsoft Windows Terminal Server (Windows 2000 Terminal Services, for 5 users, $750; for 20 users, $2,670;

Terminal Services Internet Connector License, for 200 concurrent users, $10,000; www.microsoft.com). MetaFrame makes disaster recovery easier

by letting you join multiple servers—even geographically dispersed servers—into a server farm. If some servers go off-line, the others pick up the

load, thus providing load balancing and server redundancy. Of course, when the fallback servers are connected across a slow connection, this

configuration won’t suffice.

Since client machines are not doing any processing, disaster recovery for them is easy. You can install the client software on any PC, even one that

is underpowered by modern standards, and it will be an acceptable thin client. If you run a Windows PC thin client, such as one of the many different

models available from Wyse, setup doesn’t even require configuring Windows, although you must provide the server’s IP address. Many products have

management software (such as Wyse Rapport, custom pricing, www.wyse.com) that automates the configuration of these devices.

We tested thin-client devices from several vendors in our April 4, 2000, story “Thin is Back,” and we especially liked the IBM Network Station 2200

and 2800 ($630 and $820 street, respectively; www.pc.ibm.com/nc), the Neoware NeoStation 2300 and 3000C ($540 and $400 respectively;

www.neoware.com), the Sun Ray 1 ($400, www.sun.com), and the Wyse Winterm 3360SE ($850). The Neoware and Sun products both received our

Editors’ Choice for that story.

Another highlight of thin-client computing is that it is designed for remote-access workers, making it ideal for disaster recovery. If your company’s

employees need to work remotely for a period of time (either from some other office or even from home), they can do so easily and seamlessly with

thin-client systems. You don’t even need to install client software on their systems; you can set up a Web page using an ActiveX control or

Netscape plug-in that connects to the server, which will require some programming with Terminal Server. Fortunately, Citrix NFuse (free download,

www.citrix.com) easily creates application links inside Web pages. Deploying these remote or Web-based applications, however, does have some

caveats. You will have to wager flexibility, remote access, and recovery capabilities against security.

There are applications that don’t work well in a typical thin-client environment, but they are usually apps that aren’t critical to business, such as

streaming video and games. In general, you should avoid applications that require intensive screen operations, such as Adobe Photoshop. Also,

applications that are very memory- and computing-intensive tend to slow down unacceptably, because they are sharing a CPU and memory with

other applications on the server. If these types of applications are used heavily in your organization, you should really consider having backup

workstations available.

Even when your users normally run Windows on fat clients, you can still use thin-client systems for disaster recovery. As long as you keep your

standard applications installed and make sure that they are configured correctly for a thin-client scenario, you can switch over to a thin client in a

disaster. Such a plan requires that your users store all data on the server in standard, accessible locations, instead of on their local hard drives, so

you can quickly configure applications to find their data.

Market share in the thin-client platform arena continues to be dominated by Citrix and Microsoft—a combined 90 percent share—especially among

Microsoft Windows NT and 2000 environments. Though MetaFrame is available for Unix platforms, third-party products are often used to support and

run them in a mixed environment.

There are other platforms and vendors to consider. For example, Tarantella Enterprise 3 ($14,950 list for 50 users, $5,000 additional for the security

package; www.tarantella.com) comes from a small company that split off from SCO and has received accolades for creating products that run in a

mixed-platform environment without additional product support.

The X Window System (often abbreviated as X), a client/server windowing system developed at MIT, is not usually considered a practical

remote-access method in office environments, because unlike RDP and ICA (the Microsoft and Citrix protocols, respectively), X is not optimized for

low-bandwidth connections. But in an emergency or for system administration tasks, X could be useful as a short-term solution.

Moving your applications from standard Windows or Unix platforms to Web hosting with a browser front end makes your clients truly thin and

portable. Users can access them from anywhere they have an Internet connection. But the limitations of this approach are profound. First,

development of these applications requires substantial custom design. Second, workers today demand the power and responsiveness of real user

interfaces, like those of Microsoft Office applications. Most likely, anything you build into a Web interface won’t satisfy them. RDP and ICA clients

can, however, connect to any server on the Internet and be accessible from anywhere.

Very few disaster recovery strategies flow so clearly from other legitimate administrative goals as does thin-client computing. With your disaster

recovery strategy, you also get better security and easier support and administration, provided that you host your servers on your own

infrastructure. Thin-client computing requires active and expert administration, but few approaches allow your organization to return to a rich

computing experience so quickly

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