Possible states for xen resource pools.
A pool may be ‘created’, in which case the admin has triggered its creation, but the underlying hypervisor pool has not actually being set up yet. An pool may be ‘changing’, meaning that the underlying hypervisor pool is being setup. An pool may be ‘active’, in which case the underlying hypervisor pool is up and running. An pool may be ‘dismissed’ when it has no hosts and it has been deleted. An pool may be in ‘error’ in all other cases. A ‘created’ pool becomes ‘changing’ during the first request of adding a host. During a ‘changing’ status no other requests will be accepted; this is to allow the hypervisor layer to instantiate the underlying pool without any potential race condition that may incur in master/slave-based configurations. The pool goes into the ‘active’ state when the underlying pool has been correctly instantiated. All other operations (e.g. add/remove hosts) that succeed will keep the pool in the ‘active’ state. If a number of continuous requests fail, an ‘active’ pool goes into an ‘error’ state. To recover from such a state, admin intervention is required. Currently an error state is irreversible, that is, in order to recover from it an pool must be deleted.
Checks if aggregate is a hypervisor_pool