[ad_1]
Native command queuing allows SATA hard drives to manage their own queue of read and write requests, reducing physical wear and tear and speeding up information retrieval time. It reorders commands to reduce seek time and waiting between commands, and can send write requests to the head of the queue when the processor is busy. This technology is also used on some solid state drives.
Native command queuing is a system that allows Serial Advanced Technology Attachment (SATA) hard drives to manage their own internal queue of read and write requests. On systems that do not use native command queuing, the unit executes commands in the order they were received from the main system. Native command queuing allows the unit to reorder commands to make the recovery process more efficient. This speeds up the information retrieval time and reduces physical wear and tear on the drive.
The data on a hard drive is stored on wafer-thin magnetic sheets called platters. Each unit has several plates, all of which contain information. Hard drives use an arm similar to that of a turntable to read and write to the platter. As the platter spins, the arm moves back and forth over the sections of the platter that contain the data.
When viewed by a human, the data on a hard drive appears totally random. Two related pieces of information can be widely spaced on the unit. To read both pieces, the arm finds the first and then moves into position to locate the second. If the drive receives one read or write command after another, the arm will have to move constantly to catch up with the data. If each of the commands requires the arm to move to the opposite side of the same platter, a lot of time is lost in the back-and-forth process.
Using native command queuing, the unit can choose the order in which to execute a given set of commands. Essentially, it does as many operations as possible in one area, then moves to a different area. This means that the unit has reduced seek time and waiting between commands. As an added side benefit, the drive spends less time performing unnecessary movement. This will reduce wear on the unit by a small amount.
Advanced systems can take advantage of another benefit of native command queuing. When a processor is busy and unable to accept commands, the drive can send all write requests to the head of the queue. Because the processor is too busy to accept read commands, the drive can choose not to resolve any of them. This can result in a huge performance boost, especially in systems with multiple drives and multiple cores.
This technology is also used on some forms of solid state drives. These units don’t use the tonearm and platter system of the standard units, so they generally run much faster. Since they are so fast, they will often run faster than the rest of the system and end up as the bottleneck. Using native command queuing, they can reorder their commands to send reads when possible and writes when the system is lagging.
[ad_2]