Masterminded by Eric Harrison, an employee of the Multnomah Education Service District in Portland, Oregon, K12LTSP is available in both Fedora Core and CentOS-based editions. The distribution is in widespread use throughout North America and parts of Europe, and, together with Edubuntu and Skole Linux, is generally considered one of the leading educational versions of GNU/Linux.
Arkiletian's lab consists of a single server and 30 clients. The lab's size makes it less complex than some K12LTSP installations that are deployed school-wide, but still large enough to make it a representative case study.
Setup and installation
K12LTSP uses the Anaconda installer, and can be used as a workstation distribution. Unsurprisingly, however, installing the software as a thin client is more complicated. The K12LTSP site gives a listing of hardware requirements for servers and clients, but Arkiletian stresses that these are minimums. Based on his experience over the last three years, he lists recommended requirements that are generally more demanding.
For the server, Arkiletian favors a dual processor, so that a runaway process can be killed without disrupting a class in session. He also advises two SCSI hard drives, although he allows that some of the recent SATA drives might be fast enough and reliable enough to be suitable replacements. Either way, he suggests that the hard drives be set up to mirror each other in a RAID 1 array. The server should have 100MB of RAM per client, rounded upwards -- twice what the K12LTSP site suggests -- in order to accommodate the use of memory-hungry programs such as OpenOffice.org. It also requires two Ethernet cards: one to create a private network on a hub for the clients, and one to connect to the rest of the network.
For client machines, clock speed is relatively unimportant, although anything less than a 100MHz Pentium is likely to have an ISA bus and require manual configuration. Nor is more than 4MB of memory on the video card needed in a typical class. What is important is RAM. Arkiletian finds that the 64MB listed on the K1LTSP site sometimes results in hard disk thrashing. He recommends doubling that, as well as using a light window manager such as IceWM instead of GNOME or KDE. In addition, clients need a 100Base-T Ethernet card. Older client machines may also need USB ports so that students can use memory sticks.
In the latest version, K12LTSP's packages are based on Fedora Core 6, with additions from Fedora Extras. The packages include standard free software for desktops, including Firefox and OpenOffice.org, which Arkiletian describes as the programs most widely used in his school outside of computer classes.
However, the distribution also includes its own unique touches, often in the form of scripts for specific purposes, such as integrating with other operating systems or restoring the default desktop on the clients, and are probably unknown to most teachers beforehand except, in some cases, as an icon on the desktop.
From the end user's perspective, the most obvious difference between this operating system and less specialized distros is the extensive range of educational software K12LTSP provides, such as Tuxtype, gPeriodic, and Celestia, the 3-D space simulator. In the latest version, the list of educational software has grown so long that it is divided into two sections -- one for kindergarten to grade five, and one for grades six and above.
For teachers, the outstanding feature of K1LTSP is Fl_TeacherTool. Written by Arkiletian, Fl_TeacherTool allows teachers to interact with client machines via VNC. At a glance, teachers can see what clients are in use, and what processes each is running. By clicking the Monitor button, they can see the desktops of other clients on their own machine. If a student is doing something he shouldn't, the Control button lets teachers take control of the student's desktop.
In addition, Fl_TeacherTool has several controls specifically for teaching. With the Distribution function, teachers can send files to students. Broadcast is even more powerful, sending copies of whatever the teacher is working on directly to one or more students' desktops so that they can follow along, and eliminating the need for a white board or handouts. Broadcast is especially useful in detailed work such as computer programming, where students need to pay close attention to what is happening.
The main drawback of Fl_TeacherTool is its use of the Fl toolkit rather than more widely used GTK or Qt. Yet, despite the name, Fl_TeacherTool is not just for teachers; potentially, it could be used by any administrator who needs to interact with users.
Advantages and disadvantages
After running his K12LTSP lab for nearly three years, Arkiletian sees distinct advantages to client/server computing. Because it uses thin clients, maintenance is low. Software does not have to be installed on each client -- although the option is available -- and clients can be swapped out easily when they fail. "It turns clients into an appliance," Arkiletian says.
More importantly, running K12LTSP gives new life to old labs. Some of the machines in Arkiletian's lab are seven or eight years old, and still in service long after their use as workstations is past. Not only are they kept out of landfills, but running them is a major cost-saver. Even with memory upgrades to client machines and a state-of-the-art server, Arkiletian estimates that his lab cost only $4,000 to set up -- about a tenth the cost of buying replacement workstations. More recently, the money that his lab has saved over the years has allowed his school to invest in a new Mac OS X lab, giving students a chance to explore a variety of different computing environments.
At the same time, Arkiletian admits that K12LTSP labs have their limitations. They are suited only to standard computing. For memory-intensive activities such as animation, they are impractical regardless of how much RAM is in the servers and clients, because the memory swapping is too frequent. However, for the average class, the environmental, economic, and pedagogical arguments that can be made in favor of K12LTSP are exactly the sort that can persuade school boards to experiment with free software.
Bruce Byfield is a computer journalist who writes regularly for NewsForge, Linux.com, and IT Manager's Journal.