what is the function of hard disk drive
Hard disk drive A hard disk drive (HDD), hard disk, hard drive or fixed disk[b] is an electromechanical data storage device that uses magnetic storage to store and retrieve digital information using one or more rigid rapidly rotating disks (platters) coated with magnetic material. The platters are paired with magnetic heads, usually arranged on a moving actuator arm, which read and write data to the platter surfaces.[2] Data is accessed in a random-access manner, meaning that individual blocks of data can be stored or retrieved in any order and not only sequentially. HDDs are a type of non-volatile storage, retaining stored data even when powered off.[3][4][5]
Hard disk drive HDD data transfer rate depends upon the rotational speed of the platters and the data recording density. Because heat and vibration limit rotational speed, advancing density becomes the main method to improve sequential transfer rates. Higher speeds require a more powerful spindle motor, which creates more heat. While areal density advances by increasing both the number of tracks across the disk and the number of sectors per track,[113] only the latter increases the data transfer rate for a given rpm. Since data transfer rate performance tracks only one of the two components of areal density, its performance improves at a lower rate.[citation needed]
Solid-state drive A solid-state drive (SSD) is a solid-state storage device that uses integrated circuit assemblies as memory to store data persistently. It is also sometimes called solid-state disk;[1] the word "disk" is inappropriate since SSDs do not have physical disks. SSDs primarily use traditional hard disk drive (HDD) interfaces, such as SATA and SAS, greatly simplfying usage of SSDs in computers.[2] Following the initial acceptance of SSDs with HDD interfaces, new I/O interfaces like M.2 and U.2 have been designed to address specific requirements of the Flash memory technology used in SSDs.
Hybrid drive In computing, a hybrid drive (solid state hybrid drive â€“ SSHD) is a logical or physical storage device that combines a faster storage medium such as solid-state drive (SSD) with a higher-capacity hard disk drive (HDD). The intent is adding some of the speed of SSDs to the cost-effective storage capacity of traditional HDDs. The purpose of the SSD in a hybrid drive is to act as a cache for the data stored on the HDD, improving the overall performance by keeping copies of the most frequently used data on the faster SSD.