Product Documentation

Introduction to Basic Tasks

May 03, 2013
Important: Workload Balancing (WLB) and its functionality has been removed from XenServer version 6.2 and higher. Applications, code, or usage that depend WLB will not function in XenServer version 6.2 and higher. See CTX137333 for details.

Workload Balancing is a powerful XenServer component that includes many features designed to optimize the workloads in your environment, such as host power management, the ability to schedule optimization-mode changes, and running reports. In addition, you can fine-tune the criteria Workload Balancing uses to make optimization recommendations.

However, when you first begin using Workload Balancing, there are two main tasks you will probably use Workload Balancing for on a daily (or regular) basis:

  • Determining the best host on which to start a virtual machine
  • Accepting Workload Balancing optimization recommendations

For information about obtaining and configuring the Workload Balancing virtual appliance, see the Workload Balancing Quick Start.

Determining the best host on which to start a VM

See also Choosing an Optimal Server for VM Initial Placement, Migrate, and Resume.

Workload Balancing can provide recommendations about the host Determining the host on which to start a VM (VM placement) is handy when you want to restart a powered off virtual machine and when you want to migrate a virtual machine to a different host. It may also be useful in XenDesktop environments.

Accepting Workload Balancing recommendations

See also Accepting Optimization Recommendations.

After Workload Balancing is running for a while, it begins to make recommendations about ways in which you can improve your environment. For example, if your goal is to improve VM density on hosts, with the appropriate settings, Workload Balancing will issue a recommendation to consolidate virtual machines on a host. Assuming you are not running in automated mode, you can choose to either apply this recommendation or just simply ignore it.

Both of these tasks, and the way in which you perform them in XenCenter, are explained in more depth in the sections that follow. Another frequently used task is running reports about the workloads in your environment, which is described in Generating and Managing Workload Balancing Reports.

Important: After Workload Balancing is running for a period of time, if you do not receive optimal placement recommendations, Citrix strongly recommends you evaluate your performance thresholds as described in the Workload Balancing Administrator's Guide. It is critical to set Workload Balancing to the correct thresholds for your environment or its recommendations might not be appropriate or occur at the correct times.