To ensure that investments in server hardware, a virtualization strategy or a private cloud pay off, it’s important to track systems’ performance over time—but with today’s mix of physical and virtual environments and the added complications posed by multiple hypervisors, picking the right monitoring tools for your environment can be complex. This chapter explains the benefits of server performance monitoring tools and explores their common features. We also cover special features and best practices for choosing and implementing performance monitoring tools, emphasizing the importance of testing and helping readers choose tools with analytical features that will allow them to apply the reported data to improve server performance and capacity planning.