Product Documentation

Excluding Hosts from Recommendations

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.

When configuring Workload Balancing, you can specify that specific physical hosts are excluded from Workload Balancing optimization and placement recommendations, including Start On placement recommendations.

When to exclude hosts

Situations when you may want to exclude hosts from recommendations include when:
  • You want to run the pool in Maximum Density mode and consolidate and shut down hosts, but there are specific hosts you want to exclude from this behavior.
  • When two virtual-machine workloads always need to run on the same host (for example, if they have complementary applications or workloads).
  • You have workloads that you do not want moved (for example, domain controllers or SQL Server).
  • You want to perform maintenance on a host and you do not want virtual machines placed on the host.
  • The performance of the workload is so critical that the cost of dedicated hardware is irrelevant.
  • Specific hosts are running high-priority workloads (virtual machines), and you do not want to use the High Availability feature to prioritize these virtual machines.
  • The hardware in the host is not the optimum for the other workloads in the pool.

Regardless of whether you specify a fixed or scheduled optimization mode, hosts excluded remain excluded even when the optimization mode changes. Therefore, if you only want to prevent Workload Balancing from powering down a host automatically, consider not enabling (or deselecting) Power Management for that host instead as described in Optimizing and Managing Power Automatically.

To exclude hosts from placement and optimization recommendations

  1. Select the pool in the Resources pane, click on the WLB tab, and then click Settings.
  2. In the left pane, select Excluded Hosts.
  3. In the Excluded Hosts page, select the hosts for which you do not want Workload Balancing to recommend alternate placements and optimizations.