However, managed resources are serially reusable .
Identical resources belong to resource classes .
For instance, most processes don't care which tape drive they get out of the pool of identical drives. The resource manager fields requests from user processes to allocate and release resources. 1. return the resources to the pool of unused resources. Some clean up operation may be needed, such as rewinding a tape drive. 2. refuse allocate the resource to another process until notified that it is safe to do so.