1. A computer program product for policy based virtual resource allocation, the computer program product comprising: one or more computer readable tangible storage media and program instructions stored on at least one of the one or more storage media, the program instructions comprising: program instructions to identify a number of host resources specified by host resource requirements for a first resource consumer; program instructions to, responsive to determining that the host resource requirements includes a list of host resource pools for the first resource consumer, identify a first set of eligible host resource pools, wherein the first set of eligible host resource pools includes at least a first host resource that is re-allocable from an inactive second resource consumer; program instructions to allocate to the first resource consumer, host resources from the first set of eligible host resource pools based on an allocation policy that includes one or more parameters for allocating host resources, wherein the allocated host resources from the first set of eligible host resource pools include the first host resources; program instructions to, responsive to determining the first host resource no longer has an amount of available virtual adapters that meets a maximum capacity parameter of the one or more parameters, deactivate the first host resource, wherein the first host resource remains allocated to the first resource consumer; and program instructions to allocate to the first resource consumer, a second host resource that has the amount of available virtual adapters that meets the maximum capacity parameter.