A data storage device includes a shared command queue, a queue controller, a processor, and a memory. The command queue is configured to queue a plurality of jobs transmitted from a plurality of host processors. The queue controller is configured to classify the plurality of jobs into a plurality of levels of jobs according to priority threshold values and assign jobs of the plurality of levels of jobs the processor. The processor is configured to process the jobs assigned by the queue controller. The memory may store data needed to process the job.