So far, this book has focused on up-front design and configuration of an email server. The goal of this chapter is to provide some methodology and explain the use of tools that will assist the email administrator in determining the cause of poor email server performance and rectifying the situation. Over the years, operating systems have grown increasingly sophisticated. Today, several levels of data caches are typically internal to the operating system kernel. Most internal data structures are dynamically sized and hashed, so that they no longer have fixed extents and table lookups remain rapid as the amount of data they contain grows. This increased sophistication generally has been for the best, as these additional variables ensure that operating systems require less manual intervention to get them to work well in a high-performance capacity. Nevertheless, a system administrator needs to be aware of two facts. First, these benefits can have side effects. Second, this extra tuning often makes troubleshooting more difficult. |