by Tom Zeller  Designing Novell Directory Services The backbone of Novell NetWare, Novell Directory Services (NDS) lets NetWare function elegantly in a very large site with many servers or in an enterprise with geographically dispersed sites. NDS provides the home for information about users, passwords, groups, servers, volumes and applications. If NDS is not functioning smoothly, chances are your file service isn't either. Identifying Design Parameters In designing your NDS tree, keep four important goals in mind: 1. Minimizing network traffic across slow links 2. Assuring fault tolerance in the NDS system 3. Providing acceptable performance for the user 4. Accommodating the management model of your organization Keep in mind that maximizing one goal might result in less than optimal results for another goal. If you can recognize these trade-offs and decide the relative priorit y of your organization's goals, you'll be able to design a successful NDS system. Some examples of these trade-offs: 1. The structure of the network is probably the most important factor in the layout of the directory structure. Slower links need to be protected from unnecessary chatter. This effects decisions about partitioning and replicating the database. Additionally, each user login over a WAN link consumes precious bandwidth. However, creating replicas closer to the user may require NDS to replicate over the WAN link, a task that also consumes bandwidth. 2. Similarly, creating additional replicas of partitions creates additional redundancy, making the system more robust. However, doing so also consumes CPU in the form of replication overhead. 3. Moving replicas closer to the user provides better performance from the user's perspective. But also can cause replication over slower links, consuming bandwidth. 4. Creating a centralized container for user offers several technical management advantages. However, if decision-making or user management is decentralized in your organization, such a model will not meet the needs of the widespread support providers. 5. A requirement for bindery services (a mechanism to emulate the method of handling user and groups used by earlier versions of NetWare) on some servers could have a profound affect on how the directory is partitioned. It could result in a design that consumes significant WAN bandwidth. However, if the service is required, there may be little choice. Tom Zeller has designed and managed one of the largest NDS installations in existence, containing 29,000 users and 50 servers. He has provided NetWare support to Indiana University for 10 years, and has been a CNE since 1991. He is also a Microsoft Certified Product Specialist for Windows NT Server and Workstation 3.51 and 4.0. Print This Page E-mail this URL