Product Documentation

Workload Balancing Basic Concepts

May 02, 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 captures data for resource performance on virtual machines and physical hosts. It uses this data, combined with the preferences you set, to provide optimization and placement recommendations. Workload Balancing stores performance data in an internal database: the longer Workload Balancing runs, the better its recommendations become.

Workload Balancing recommends moving virtual-machine workloads across a pool to get the maximum efficiency, which means either performance or density depending on your goals. Within a Workload Balancing context:

  • Performance refers to the usage of physical resources on a host (for example, the CPU, memory, network, and disk utilization on a host). When you set Workload Balancing to maximize performance, it recommends placing virtual machines to ensure the maximum amount of resources are available for each virtual machine.
  • Density refers to the number of virtual machines on a host. When you set Workload Balancing to maximize density, it recommends placing virtual machines on as few hosts as possible, while ensuring they maintain adequate computing power, so you can reduce the number of hosts powered on in a pool.

Workload Balancing lets you modify settings for placement (performance or density), power management, automation, metric weightings, and performance thresholds.

Workload Balancing will not conflict with High Availability settings; High Availability settings always take precedence.