US Patent 7925805 Critical resource management

In one embodiment, a method of managing critical resource usage in a storage network comprises receiving, in a storage controller, an input/output operation from a host, wherein the input/output operation identifies a storage unit, placing the input/output operation in a waiting queue, determining a maximum queue depth for at least one critical resource in the storage network required to execute the input/output command against the storage unit, and blocking one or more subsequent input/output commands from the host for the storage unit when the wait queue for the critical resource exceeds the maximum queue depth.