This article provides a brief introduction to the Data Center Linux (DCL) initiative sponsored by the Open Source Development Lab (OSDL). I'll describe our goals, show how we achieve those goals though our committees and working groups, and provide some examples of some DCL-driven activities and challenges.

The OSDL Data Center Linux is one of three OSDL initiatives created so that OSDL members can work together to accelerate the use of Linux for enterprise computing. The DCL initiative was formed with the intent of promoting the adoption of Linux-based servers in the enterprise across its many tiers: edge, infrastructure, application, and database. It brings together interested parties to accelerate the availability of stable, fully featured, integrated, customer-available solutions that run on Linux. The initiative addresses both mid- and high-end multiprocessor servers as platforms for mission-critical enterprise applications and databases.

DCL has three committees - steering, marketing working group (MWG), and technical working group (TWG) - made up of OSDL members and dedicated OSDL staff. These committees work within an ecosystem that integrates these activities within the framework of open source development.

DCL Steering Committee Activities
The scope of issues related to an Enterprise Data Center is extremely broad. The DCL steering committee acts to focus the efforts of the initiative. For example, steering directed that DCL identify the most important applications used in data centers today. From that, DCL can identify the workloads ready for Linux adoption and, conversely, can flag the marketing and technical inhibitors to running key applications on Linux in the enterprise (see Figure 1).

DCL Marketing Working Group (MWG) Activities
DCL has a marketing working group for two reasons. First, many of the inhibitors to Linux adoption are not technical. In fact, the Linux operating system has improved so much that this is the situation more and more. So a marketing group is needed to evaluate those nontechnical needs. Second, MWG sets DCL goals and priorities for such things as Linux awareness and confidence, global enterprise services and support, software availability for priority applications, training and education, care and feeding of the development community, stability, and total cost of ownership. In addition to determining the DCL marketing effort, this helps the technical working group (described next) focus on the most important capabilities and activities needed to support the DCL marketing goals.

MWG produces collateral to document their goals, create awareness for Linux in the Data Center, identify important workloads used for DCL analysis activities, and encourage interest in joining DCL activities. They report any resource issues for resolution to the steering working group.

DCL Technical Working Group (TWG) Activities
DCL's technical working group is responsible for identifying and removing the technical inhibitors to Linux adoption. When the initiative was first formed in 2002, the focus was on the Linux kernel. As the kernel has matured, TWG's scope has expanded to the whole software stack, including both the kernel and above the kernel.

Based on the MWG goals, TWG tracks eight categories of Data Center concerns: scalability, performance, manageability, RAS (reliability, availability, serviceability), standards, security, clusters, and usability. To set the priorities of the effort, the capabilities required for the data center in these categories are described and mapped for the application workloads identified by marketing. For the highest priority capabilities, the gaps in maturity are identified and TWG works to close those gaps.

DCL members want to be good open source citizens. Moving from a closed to an open source world requires a shift in culture for those making the transition. So, TWG assists member and non-member assimilation into the community. One DCL effort underway is to create the environment whereby more storage drivers are found exclusively in the mainline kernel. There is a lot of good documentation on formatting style and coding rules for open source drivers. However, the knowledge about what is the right way to interact with the kernel community was found to be lacking and is under development.

Special Interest Groups and Use Cases Link the Ecosystem
As previously stated, the working groups identify and remove the technical and marketing inhibitors to Linux adoption. It's equally important to know that DCL is not another Linux distribution. To ensure that solutions are available to end-customers, our approach is always to drive kernel-based solutions into the mainline kernel.org kernel. Any open-layered solutions (for example, the NFS user-level code or statistics-gathering utilities) are driven through community-recognized forums.

A challenge for DCL TWG, and indeed for all the initiatives, is to map the capabilities needed to:

• Solutions that need to be developed
• The gaps for solutions that do exist
• Solutions that could satisfy the needs of all the initiatives

To overcome these challenges, OSDL created special interest groups (SIG) in high-priority subject areas (e.g., storage networking, hotplug, clusters, security) that our members use as cross-initiative technical forums to identify the use cases and gaps (coding, testing, and documentation) needed to provide enterprise-worthy solutions on Linux (see Figure 2).

These forums are completely open so that we can include non-member maintainer participation. SIGs are not meant to replace the active community developer mail lists. If the existing community can deal with an issue, there's usually no need for activity on the part of a SIG. SIG activities are made public on their home pages.

Example: Storage Networking SIG
One example of a SIG activity is that of the Storage Networking SIG, which includes a focus area for NFS version 4. The SIG determined that the development community was progressing with no need for intervention, except that no one could answer the question "What testing is needed to make NFS v4 customer ready, and who will be doing the testing." The SIG then sponsored an effort led by an OSDL test engineer to create a prioritized NFS V4 test matrix to:

• Identify what tests needed creating or updating due to new features in NFS V4.
• Determine and create the use cases that should drive the testing.
• Provide a description of each test and testing configuration needed.
• Track who will do or has performed the test.
• Post all of the above to attract testers and determine NFS v4 stability.

This information helps the community know what testing is highest priority to more effectively assign test resources and not duplicate efforts. It also means that the testing gaps can be identified and raised to DCL Steering for action. The SIG gathers information from the NFS v4 developers on their own forums: it's not required for the developers to join the SIG. Those who wish to join are certainly welcome. For more information on this project, see the References section below.

Use Cases
The use case is an important, accepted tool used by the community to explain how open source software will be used. There are many motivations to write use cases. Since developers may not have experience actually working in a large data center, use cases can help them understand end-user problems so developers can accept the need for a solution and can determine the best solution.