Native Command Queuing
Hard Drive Recovery - Native Command Queuing
Native Command Queuing is a method used to increase the performance of SATA hard disks. It allows individual hard disk to optimize the execution of read and write commands. This in turn reduces the drive head movement and increases the performance and life of the drive. NCQ finds the best use in server-type applications where multiple read/write requests occur simultaneously.
NCQ succeeds Parallel ATA’s version of Tagged Command Queuing (TCQ). ATA TCQ did not find much acceptance because it required that ATA host bus adapters use ISA bus device protocols to interact with the operating system.
NCQ differs from ATA TCQ in that the host bus adapter programmed its own first party DMA engine with the DMA parameters that the CPU gave when it issued the command. Also, the CPU must be interrupted by the ATA device, and in turn, CPU can ask the ATA device which command is ready to be executed and can program the ATA host adapter’s third party engine.
NCQ can be enabled in the SATA host bus adapter. For this, the appropriate driver must be loaded into the operating system. NCQ is also used in the later versions of solid-state drives where the drive encounters latency on the host. For example, Intel’s X25-E Extreme solid-state drive uses NCQ to make sure that the drive has commands to process while the host system is busy processing CPU tasks.
