User Visible Objects
oVirt allows administrators to group hosts and storage in a hierarchy of Hardware Pools. Each Hardware Pool may contain any number of physical hosts and storage pools as well as child hardware pools.
In addition, a hardware pool may contain a number of Virtual Machine Pools, each of which contain a collection of Virtual Machines which can migrate among any of the hosts in the Hardware Pool
By default, a single Hardware Pool is created called 'default'. This top-level pool is where new hosts are added to the system. All subsequent Hardware Pool are children of this default pool (or of other pools in its subtree)

