The question of whether Linux's total cost of ownership (TCO) is lower than that of Windows or other operating systems has inspired many fierce debates among enterprise IT professionals.

On initial review, the answer seems simple. Linux's low- or no-cost license fees should drive down the TCO of the open source OS, compared to Windows or other flavors of Unix. But the debate--like the larger debate of Linux vs. Windows--is complicated by administration and support costs that vary for each installation.

TCO is hard to pin down
Most analysts, if asked whether Linux has a lower TCO than other systems, will answer, "It depends." That's because a wide variety of factors affect any TCO calculation: what function you're using Linux for, what kind of hardware (and how much of it) you're using, if you're transitioning from Windows or starting from the ground up, and if your IT staff has any experience with a Unix-like OS.

Those variables and others--such as what distribution of Linux is in play and the version of Windows or Unix it's being compared with--make it impossible to plug numbers into a preset formula and spit out an easy answer, explained Al Gillen, research director of systems software for tech analyst IDC, which has been doing TCO studies for several years.

"It's not trivial to figure out, and even when we do a TCO study, you have to remember that our TCO studies are extremely specific in nature," Gillen said. The IDC studies examine a specific workload on two specific kinds of systems with specific kinds of hardware. "The chances are the stack that we select is probably not going to be representative of anybody's real-world configuration," he added.

The numbers you can measure and compare with often end up with complex explanations attached. For example, take licensing fees, where Linux easily beats Windows or other Unix OSs. When you figure out TCO over a three- to five-year period, the initial licensing costs end up being a miniscule piece of the cost, compared with large-ticket items like Linux administration and support, Gillen noted.

"The cost of acquisition of software, hardware--all the things you buy up front--that's a minority element of the total cost of ownership of any operating system," he said. "Whether you pay $2,000 for a Windows license or $49.95 for a boxed copy of Linux, over the course of its lifetime, that ends up being a minor cost."

Gillen pointed out that $2,000 divided over five years is $400. "What is the cost for a technical support professional per hour to be there on staff? Probably a couple of hundred dollars," he noted.

Administration and labor costs

The cost of administration
Microsoft has argued that the Windows administrator costs easily wash away the Linux licensing cost advantage. The standard Windows argument is that a larger pool of Microsoft-certified administrators exists, so a Windows admin should cost less than a Linux admin.

Gillen said the argument seems to make sense initially, but like other TCO arguments, it is more complicated than it appears.

As one Linux consultant noted, plenty of MCSEs are available, but that doesn't mean they're all qualified.

"If you throw a rock, you'll probably hit an MCSE in the head," said Brian Schenkenfelder, president of Kentucky-based Linux consultancy n + 1. "The problem is, how many of them are any good? There are a lot of paper tigers out there, and that's true of both sides."

Schenkenfelder argues that the typical Linux administrator can handle more than the typical Windows admin.

"What I've found is that a Linux administrator who knows what he's doing should be able to administer two to three times the amount of boxes a Windows administrator should be able to administer," he said.

A July study, conducted by Chad Robinson, senior research analyst at tech/business researcher Robert Frances Group (RFG), supports Schenkenfelder's claims. Robinson acknowledges that experienced admins for Linux or Solaris can be more expensive in some parts of the United States but noted that many of them have been working with Unix for dozens of years.

"One of the things that Microsoft is starting to lose out on now, and I'm not sure they realize this yet, is that they still claim Windows administrators are cheaper," Robinson said. "But the flip side of the same coin is that if one of my administrators on a Windows environment can manage only 10 to 15 systems at a time, but my Solaris admin or my NetBSD or my Linux admin can manage 1,000 servers at a time, I need fewer admins. Sure, the salary's more expensive, but I get more life out of them."

Labor costs significantly lower
RFG's study, "Total Cost of Ownership for Linux Web Servers in the Enterprise," compares the TCO of Linux to Solaris and Windows. Robinson compared the cost of "processing units"--the number of servers that would be required to process 100,000 hits per day, and tracked the costs over three years. Linux supporter IBM commissioned the RFG research for the study paper.

Robinson compared Red Hat Linux 7.3 running Apache to Solaris running Apache, and to Windows running IIS. The comparison was all on x86 architecture, using a relatively small sample of 14 companies running mission-critical Web servers. The study found that Windows needed an average of 7.6 servers for a processing unit, Linux needed 7.4, and Solaris needed 2.2.

The software purchase costs per processing unit varied greatly. Linux had a one-time software purchase cost of $400, with most surveyed companies buying a few copies to test different distributions of Linux and then using the free download version on most servers. Solaris had a one-time cost of $27,500 per processing unit, and Windows' up-front cost was $5,320, with a total licensing cost of $7,980 over three years.

Hardware and maintenance costs were nearly the same for Windows and Linux; Solaris cost about 10 times more. In the area where Microsoft expects to pull ahead--server admin costs--the results are what Microsoft would expect, according to Robinson.

In the survey, Linux admin salaries were slightly higher than Windows admins, with Linux at $71,400 per admin, and Windows at $68,500 per admin. But Linux admins took care of an average of 44 servers and Windows admins an average of 10. So the salary per processing unit was Linux, $12,010, and Windows, $52,060.

"And finding Linux experience is not difficult anymore," Robinson noted. "Most of the customers told us that their Solaris admins basically picked it up and worked with it within a couple of weeks."

Bottom line for CIOs

Support savings
The RFG study also looked at system support costs. Among the companies surveyed, the study found few that were paying for Linux support; instead, they used free support online. Obviously, commercial support options would add to the Linux TCO equation.

According to the study, the three-year cost of a 100,000-hit processing unit was significantly different among the systems:

• Solaris: $561,520
• Windows: $190,662
• Linux: $74,475

Unique cost factors play in
Robinson also noted that keeping up with Microsoft's licensing requirements--and with the hackers that consistently target Windows--will add to the Windows cost. He included those issues in his "soft" costs section but didn't have enough data to work them into his numbers, he explained.

"Personally, I'm not finding Windows to be less expensive to administer, but those security holes--that'll kill 'em," he said.

IDC's Gillen hasn't conducted a comparison between Windows and Linux recently, but it produced a white paper for Red Hat (a leading Linux vendor) last February comparing Linux to RISC/Unix. That paper suggested Linux provides a 1.8:1 cost advantage over RISC/Unix for Internet/intranet/extranet workloads, and a 5.5:1 cost advantage for collaborative workloads.

Making the system choice
In determining the most cost-effective system for their enterprise, Gillen suggested that CIOs do three important things before choosing Linux:

• Consider in-house expertise: More experience with a particular OS means less downtime, Gillen noted. "If you can build a more stable, more reliable configuration, I don't care what the operating system is. If you can take operating system A and make it more stable, more reliable than operating system B, however you do it, your TCO is going to be positively impacted by that higher uptime."
• Think about costs in the long term: "Don't look at it as, 'I need to get to this platform because it has better TCO.' That may be true, but there's a return on investment consideration also," explained Gillen. If you're on a Windows environment, and you're looking at Linux and thinking, 'this is really great, I've got to get to Linux,' remember that there's a fair amount of investment in moving your application technology. "You've got a really significant investment just to get to that other environment. You need to understand what that ROI is going to be to get there and will the TCO benefit over time make up the difference."
• If it works, don't jump to fix it: Ripping out a system is really big news, noted Gillen. For example, he said OpenVMS is still running in many places because it solves a business need, and because admins understand the environment, they have good reliability and scalability. "There's no benefit for them to move. If it works, leave it alone. That's really the way people have to look at things."