After you create a datacenter and add a clustered host enabled with DRS or a standalone host to your vCenter Server system, you can create a vApp.

You can create a vApp under the following conditions.

A standalone host is selected in the inventory that is running ESX 3.0 or greater.

A cluster enabled with DRS is selected in the inventory.

You can create vApps on folders, standalone hosts, resource pools, clusters enabled with DRS, and within other vApps.