A distributed storage network includes a distributed storage processing unit, which generates multiple data slices from a single data segment, and multiple different storage units to store the data slices. Each data slice is assigned to a particular storage unit for storage. The distributed storage processing unit determines which of the storage units are in a ready state, and sends data slices to the ready storage units. Data slices assigned to storage units that are not in a ready state are temporarily stored in a temporary memory, e.g. cache memory, until the storage unit becomes ready. If the intended storage unit remains in a non-ready status for too long, the slices stored in cache memory can be sent to a substitute storage unit, or discarded and reconstructed at a later time.