A home server is the server which will provide the resources for a VM in a pool. When you nominate a home server for a VM, XenServer will always attempt to start up the VM on that server if it can; if this is not possible, then an alternate server within the same pool will be selected automatically.
If you are creating a BIOS-customized VM, the OEM server from which you copy the BIOS strings will automatically be selected as the home server for the new VM.
You can change the home server configuration for a VM from the VM's Properties dialog box; see Change VM properties.
Workload Balancing (WLB) considerations
In pools with Workload Balancing (WLB) enabled, the nominated home server will not be used for starting, restarting, resuming, or migrating the VM. Instead, WLB nominates the best server for the VM by analyzing XenServer resource pool metrics and recommending optimizations.