As Published In July/August 2003

Linux Takes on the Enterprise

By David A. Kelly

How the operating system once relegated to running development projects became strong enough to run real businesses

What do American Idol winner Kelly Clarkson and Linux have in common? They've both helped fuel the success of the television phenomenon imported from the U.K. to America in 2002, albeit in very different ways. Last year Clarkson belted out tunes to become a celebrity; this year Linux servers at Mobliss, Inc., powered the cell phone voting for American Idol—the first major wireless interactive TV voting ever seen in the U.S. For Mobliss, the choice to use Linux was an easy one to make. "Linux has a proven track record of driving some of the most highly trafficked sites on the internet," says Brian Hill, chief operating officer at Seattle-based Mobliss. "The bottom line is that it gives us the ability to deploy high-powered services very inexpensively with all the features and software that we need to be in the position to set the pace in our industry."

Even the industry analysts are noting the transition. "The state of Linux has moved beyond the internet infrastructure market toward more-commercial applications such as SAP and Oracle," says Stacey Quandt, an industry analyst focusing on Linux and open source at Giga Information Group. "It's an indication that the market is maturing." But it hasn't always been so clear that Linux was the best bet for back-office enterprise servers. Even though it was widely used in development groups and Web server deployments by the late 1990s, there were still not a significant number of back-office Linux deployments for database servers or enterprise application servers. For Linux to make the transition from an IT skunk-works project to a mission-critical enterprise operating system, it needed to be modified for enterprise use, and perhaps more important, it needed to be championed by large companies with high-availability needs.

Oracle Pledges Linux Support

Enterprise customers saw Oracle's June 2002 announcement of Linux support for the Oracle9i product line (including the database, application server, development tools, and Real Application Clusters [RAC]) and Oracle's e-business applications, along with first-line support for the Linux operating system itself, as a watershed.

"Oracle's statement that it would provide first-level support for the Linux operating system was a really important one for them to make," says Mike Kennedy, CIO, New South Wales Office of State Revenue, Australia. "It was very significant to us, and I think it's significant to the IT community worldwide, that heavyweights like Oracle and IBM are both providing support for Linux." Significant enough for his organization to entrust an average of 15 million database transactions per day and the processing of almost AUS$11 billion in transactions per year to servers running Red Hat Advanced Server Linux, Oracle9i Database, and Oracle9i Application Server (Oracle9iAS).

With this level of Linux support, businesses can safely deploy Linux in a mission-critical environment and receive Linux support worldwide. From the reaction of Oracle customers, this approach seems to be working. "I would say that our decision to move to Linux on a Dell platform was a big deal for us, since we needed a very stable, secure, and scalable platform that was going to be as bulletproof as we could get," says Jeff Bialik, CFO and vice president of operations, Golden Gate University, San Francisco. "It was the marriage between Linux, Oracle, and Dell that really made it possible. Once you have the confidence that you can have a secure, stable, and scalable platform to build on, then you've got no option but to go this route because it's actually a combination of both the best price/performance and a lower-cost-of-ownership solution."

A few years ago, it might have seemed surprising that a CFO would be saying that about a homegrown operating system.

The Skinny on Linux

Initially conceived as a hobby and a tool for learning about Intel's 80386 microprocessor, Linux has grown into a multi-billion dollar wave that's sweeping the server and IT markets. In fact, in a Giga Information Group report on Linux, analysts Stacey Quandt and Bob Zimmerman estimate that Linux distribution providers accounted for a US$2.5 billion market in 2002, based on server revenues.

It all started when Linus Torvalds, a student at the University of Helsinki, created the first version of Linux almost 12 years ago in August 1991. Released as open-source software under the Free Software Foundation's GNU General Public License (GPL), it quickly grew into a complete operating-system package, with the contributions of hundreds of programmers. Since 1994, when version 1.0 was released, organizations have been able to download free copies or purchase commercial distributions from companies such as Red Hat that also provide consulting, services, and maintenance.

This raises a question that many people have about Linux—if it's released under the Free Software Foundation's GPL, shouldn't it be free? In a word, no. Any company can charge money for products that include Linux, as long as the source code remains available. The GPL allows people to distribute (and charge for) their own versions of free software. In fact, according to the Free Software Foundation, the "free" in free software refers to liberty, not price. In the foundation's definition (as embodied in the GPL), free software provides organizations the freedom to run software for any purpose, study how it works, modify it, and improve or re-release it.

Another common misconception about Linux is that it's a complete operating system. In reality Linux refers to the kernel—or core—of the operating system. Combining Linux with a set of open-source GNU programs from the Free Software Foundation turns it into what most people know as Linux—forming both the full operating system and the core of most Linux distributions. Distributions are the versions of Linux, GNU programs, and other tools that are offered by different companies, organizations, or individuals. Popular distributions include Red Hat, United Linux, SuSE, Caldera, and others. Each distribution might be based on a different version of the Linux kernel, but all migrate forward over time, picking up core changes that are made to the kernel and keeping everything in sync (if somewhat loosely).

With Linux, these new changes come through an open development model, meaning that all new versions are available to the public, regardless of their quality. "Linux's versioning scheme is designed to let users understand whether they're using a stable version or a development version," says Jim Enright, director of Oracle's Linux program office. "Even decimal-numbered releases [such as 2.0, 2.2, and 2.4] are considered stable versions, while odd-numbered releases [such as 2.3 and 2.5] are beta-quality releases intended for developers only." For example, as of May 2003, the current production version of Linux is 2.4, while the beta of the next version is 2.5 (to be finalized as 2.6 on promotion to a released version).

For much of the 1990s, Linux was primarily an experiment—something that developers fiddled with and used on local servers to see how well it worked and how secure it was. Then, with the internet boom of the late 1990s, many companies started using Linux for their Web servers, fueling the first wave of corporate Linux adoption. In fact, by 2002, Linux servers represented 30 percent of the Web server market. But even as Linux achieved greater penetration in the Web server market, something else was needed in order for it to reach the next level—for organizations to start using it for enterprise application servers, database servers, and application servers.

Oracle Goes Linux

"We'll be running our whole business on Linux," stated Larry Ellison in June 2002. What might have been a hollow statement if said by some CEOs, Ellison's stake-in-the-ground pronouncement for Linux has turned into a corporatewide crusade. In fact, Oracle's commitment to Linux in the enterprise entails migrating many of its key internal and external systems to Linux, including Oracle.com, Oracle Files Online, Oracle Outsourcing, Oracle Financials, and more. For example, Oracle Files Online is a huge internal file-sharing system—with more than 12.5 million documents—built on top of Oracle Database. Its 4TB of data is used by more than 40,000 employees, and the entire system runs on Linux.

"One reason we're moving to Linux internally is because we're saving huge amounts of money on infrastructure," says Wim Coekaerts, director of Oracle's Linux engineering team. "You can buy Intel servers for between a half and a fifth of the cost of traditional hardware, and it has about the same performance. The fact that it's an open operating system is also great." While the cost savings are good, it isn't the only benefit Oracle's reaping from the move—the company is also gaining customers' respect.

"One of the elements that was influential to me personally was Oracle's use of Linux in its own managed data center," says Sanjeev Mohan, enterprise database architect at Golden Gate University. "If you have outsourcing services from Oracle for applications or core technologies, it's going to deliver them on Linux and Dell platforms from its data center. For me, that was a very important endorsement." According to Oracle, Linux is now the preferred system for Oracle Outsourcing systems for deploying Oracle E-Business Suite and Oracle9i. "We've been using Linux as the default deployment choice for hosted customers since last summer," says Oracle's Enright. "It's providing us with lots of useful information about deploying Linux, and we're feeding that information back into the development process and to our distributors."

Another benefit of Oracle's unique requirement for supporting the Linux operating system is paying off in added stability and testing of Oracle products running on Linux. "We're doing a huge amount of extra work on Linux today that we never did before on other operating systems," says Coekaerts. "And with our 25 years of experience in working with operating systems, we know what Oracle requires to run best."

Although Oracle can't support all the hundreds of Linux distributions, it does support a variety from around the world, including selected Red Hat and UnitedLinux versions from Conectiva, SCO, SuSE, and TurboLinux. "It's very important that we make sure our open-source contributions are focused," says Enright. "We work with Red Hat and the UnitedLinux distributors and make open-source contributions into their threads, which are then combined in the Linux Common Kernel and redistributed to all the Linux providers."

With all this emphasis on Linux from Oracle, it's possible to get the idea that the company is promoting Linux instead of other operating systems. Not so. Says Coekaerts, "We believe it's the customer's choice of what operating system to run. If they want to run Oracle on Solaris, we will support them just as much as we always have and will continue to do so. All this focus on Linux is simply our way of trying to highlight the fact that we think Linux is great and that if our customers have an interest in it, we'll support them."

Moving Linux into the Enterprise

Deploying Linux in the enterprise means meeting enterprise performance requirements. And doing that took more than issuing a press release or making a bold statement. It meant dedicating a team of programmers to Linux and open source. Prior to the announcement in June 2002 of Oracle's Linux initiative, called Unbreakable Linux, Oracle formed a Linux kernel team whose goal was to make contributions to open source under GPL by working closely with Red Hat and the open-source community to deliver key enterprise functionality into Linux. On close examination, it appeared that standard Linux distributions had a number of small but serious problems that could cripple enterprise server deployments, including problems with I/O throughput, virtual memory management, scalability, and degradation under load. "It's these types of changes that we felt were necessary to give us enterprise-class support from a technology perspective," says David Dargo, vice president of the Linux program office at Oracle.

Take the case of I/O throughput—a critical component for a high-performance database. "We know that we need to be able to have a single call launch thousands of I/Os," says Enright. "We know that we need to have those I/Os complete in a timely fashion, and that if we have to wait for them to complete in sequence we'll have less throughput." However, when the Linux kernel team at Oracle initially started to explore the performance and scalability of Linux as an enterprise platform, it quickly found problems.

Asynchronous I/O—a key capability required to move large amounts of data to multiple disks—did not deliver well. Digging deeper, the team found that in the existing Linux kernel there was only a single lock for SCSI on a system. "It didn't matter if you had a half dozen controllers or one controller—there was a single lock," says Enright. "As you added hardware to increase performance you were still sharing a single lock, so there was really no noticeable improvement."

Through the work of Oracle's Linux kernel team and programmers at Red Hat, the problems with asynchronous I/O in Linux were corrected, so that as multiple devices are added they perform at speed—making it possible to improve I/O throughput through the addition of multiple devices. The revised code was released through Red Hat into the Linux Common Kernel so that over time, individual Linux distributors will adopt it. According to Enright, "It's just one example of how even Linux users that don't have Oracle in their stack will still gain benefits from the work that Oracle is doing."

In addition to this collection of enhancements that have made it into Linux distributions, Oracle and its Linux partners are working on a few more to propel Linux further into the enterprise. "In future releases, we're pushing to increase the amount of available memory, continuing to increase I/O throughput, and continuing to increase stability," says Enright.

Commitment to Open Source

Oracle's contributions to the open-source community break down into two categories: ones that are done in conjunction with Oracle's Linux partners, and ones that are released directly as open-source contributions. For example, Oracle's contributions to performance enhancements in the current Linux kernel were made with assistance from Red Hat, while its work porting the Oracle Cluster File System to Linux is available separately from standard Linux distributions as downloadable open-source programs. "We believe very strongly in being a positive example and a welcome member of the Linux open-source community," says Dargo.

To provide effective clustering in a Linux environment for Oracle9i RAC, Oracle needed to have the cluster file system under its control—rather than having to go through the standard Linux file system. As a result, Oracle ported the Oracle Cluster File System to Linux and released it to the open-source community. While it applies specifically to Oracle for now, the Oracle Linux team hopes that future variations of Oracle Cluster File System from the open-source community will find broader uses for its high-performance functionality.