Briefly discuss on Bankers algorithm?

The resource-allocation graph algorithm is not applicable to a resource-allocation system with multiple examples  for each resource type. So we go for bankers algorithm but is less well-organized that resource allocation graph scheme.

When a new procedure enters it must declare the maximum number of instances of every resource type that it may need. When a user request a set of resources, the system must verify whether the allocation of these resource will leave the system in a safe state. If it will the resources are allocated; otherwise the process must wait unless some other process releases enough resources.