As of XenServer 5.6 Feature Pack 1, the Workload Balancing documentation is no longer in the XenServer Administrator’s Guide. You can now find it on the Workload Balancing tab.

The guides from the latest release, Workload Balancing 2.1, are here:

Originally, we included the Workload Balancing documentation in the XenServer Administrator’s Guide because Workload Balancing appears in the XenCenter UI and, consequently, appears to be part of XenCenter.

However, Workload Balancing is a separate component, and some people found this location unintuitive. As a result, and to make Workload Balancing consistent with other Editions components, we have separated its documentation out into an installation guide and an administrator’s guide. Likewise, Workload Balancing now has its own readme as well.