WOW this is most comprehensive guide for troubleshooting vSphere 4, and actually any ESX 3.x as well. Hal Rosenberg you have done a great job here that will help out all VMware Admins around the World to better troubleshoot vSphere environments, congratz!
Performance problems can arise in any computing environment. Complex application behaviors, changing demands, and shared infrastructure can lead to problems arising in previously stable environments. Troubleshooting performance problems requires an understanding of the interactions between the software and hardware components of a computing environment. Moving to a virtualized computing environment adds new software layers and new types of interactions that must be considered when troubleshooting performance problems.
The attached document is the first installment in a guide covering performance troubleshooting in a vSphere environment. It uses a guided approach to lead the reader through the observable manifestations of complex hardware/software interactions in order to identify specific performance problems. For each problem covered, it includes a discussion of the possible root-causes and solutions. Topics covered include performance problems arising from issues in the CPU, memory, storage, and network subsystems, as well as in the VM and ESX host configuration. Guidance is given on relevant performance metrics to observe using the vSphere Client and esxtop in order to isolate specific performance issues.
This first installment of Performance Troubleshooting for VMware vSphere 4covers performance troubleshooting on a single VMware ESX 4.0 host. It focuses on the most common performance problems which affect an ESX host. Future updates will add more detailed performance information, including troubleshooting information for more advanced problems and multi-host vSphere deployments.