- Choosing an Optimal Server for VM Initial Placement, Migrate, and Resume
- Accepting Optimization Recommendations
When Workload Balancing is enabled and you start a virtual machine that is offline, XenCenter provides recommendations to help you determine the optimal physical host in the resource pool on which to start a virtual machine. The recommendations are also known as star ratings since stars are used to indicate the best host.
More stars appear beside host17 since this is the optimal host on which to start the VM. host16 does not have any stars beside it, which indicates that host is not recommended, but since it is enabled the user can select that host. host18 is greyed out due to insufficient memory, so the user cannot select it.
When Workload Balancing is enabled, XenCenter provides star ratings to indicate the optimal hosts for starting a virtual machine, including when you want to start the virtual machine when it is powered off or suspended and when you want to migrate the virtual machine to a different server (Migrate and Maintenance Mode).
When you use these features with Workload Balancing enabled, host recommendations appear as star ratings beside the name of the physical host. Five empty stars indicates the lowest-rated (least optimal) server. When it is not possible to start or move a virtual machine to a host, when you use the menu command for one of the placement features, the host name is greyed out and the reason it cannot accept the VM appears beside it.
In general, Workload Balancing functions more effectively and makes better, less frequent optimization recommendations if you start virtual machines on the hosts it recommends (that is, by using one of the placement features to select the host with the most stars beside it).
The term optimal refers to the physical server best suited to hosting your workload. There are several factors Workload Balancing uses when determining which host is optimal for a workload: