When you add the host to the cluster with that first option it is just saying to import all the registered machines etc into the "root" of the cluster instead of using existing resource pools. It should not delete any VM's at all other than if you had created a resource pool on the host itself. when you add to the cluster it hsould just bring everything included the VM's into the cluster. See link etc below.
The methods available for adding
hosts to a cluster are useful under different circumstances. Each method
returns a managed object reference to a task.
hosts to a cluster are useful under different circumstances. Each method
returns a managed object reference to a task.
■ | ClusterComputeResource.AddHost_Task– Adds a host to a cluster. The host name must be either an IP address, such as 192.168.0.1, or a DNS resolvable name. If the cluster supports nested resource pools and you specify the optional resourcePool argument, the host's root resource pool becomes the specified resource pool, and that resource pool and the associated hierarchy is added to the cluster. |
If a cluster does not
support nested resource pools and you add a host to the cluster, the standalone
host resource pool hierarchy is discarded and all virtual machines on the
host are added to the cluster's root resource pool.
support nested resource pools and you add a host to the cluster, the standalone
host resource pool hierarchy is discarded and all virtual machines on the
host are added to the cluster's root resource pool.
■ | ClusterComputeResource.moveHostInto_Task moves a host that is in the same datacenter as the cluster into the cluster. If the host is already part of a different cluster, the host must be in maintenance mode. |
■ | ClusterComputeResource.moveInto_Task works like moveHostInto_Task, but supports an array of hosts at a time. When using this method, you cannot preserve the original resource pool hierarchy of the hosts. |
See link below: