Hard Disk vs Hard Drive | Hard Disk vs Hard Disk Drive
Hard Disk Drives are the most common secondary storage technology in use. It offers tremendously larger capacities and higher performance compared to earlier methods such as magnetic tapes and punch cards.
Hard Disk Drive (HDD) / Hard Drive
A hard disk drive (HDD) is a secondary data storage device used for storing and retrieving digital information in a computer. Introduced by IBM in 1956, hard disk drive was the dominant secondary storage device for general purpose computers by the early 1960s and still is the dominant form of storage. The technology has improved significantly since its introduction.
A hard disk drive consists of following components.
1. Logic Board – the controller circuit board of the HDD, it communicates with the processor and controls the relevant components of the HDD drive.
2. Actuator, Voice coil and Motor Assembly – controls and drives the arm holding the sensors used to write and read the information.
3. Actuator Arms – long and triangular in shaped metal parts with the base being attached to the actuator, it is the main structure supporting the read-write heads.
4. Sliders – fixed to the tip of the actuator arm, and carry the read write heads across the disks.
5. Read/Write Heads – write and read the information from the magnetic disks.
6. Spindle and the Spindle Motor – the central assembly of the disks and the motor driving the disks
7. Hard Disks – discussed below
The hard drives are prominent due to their capacity and performance. The capacity of the HDDs varies from drive to another but has been consistently increasing over the time. In general, a modern PC uses a HDD with capacity in TeraByte ranges. For computers in specific tasks such as data centers use hard drives with much higher capacity.
The performance of the hard drive is characterized by the Access Time, Rotational Delay, and Transfer Speed. Access time is the time taken to initiate the actuator by the controller to move the actuator arm with the read/write heads into position over the proper track. Rotational delay is the time the read/write heads must wait before the intended sector/cluster rotates into position. Transfer speed is the data buffer and transfer rate from the hard drive.
Hard drives are connected to the main board using different interfaces. Enhanced Integrated Drive Electronics (EIDE), Small Computer System Interface (SCSI), Serial Attached SCSI (SAS), IEEE 1394 Firewire, and Fibre Channel are the main interfaces used in modern computer systems. Majority of the PCs uses the Enhanced Integrated Drive Electronics (EIDE) which include popular Serial ATA (SATA) and Parallel ATA (PATA) interfaces.
Hard Disc Drives are mechanical drives with moving parts inside them; therefore, over time and prolonged usage wear and tear occurs, making the device unusable.
In hard Disk drives, the data are stored using rapidly rotating discs (platters) coated with magnetic material, which are commonly known as the Hard Disks. An HDD consists of one or more solid rotating discs, also known as platters. These disks may be stacked to create a stack, which allows more space on the disk drives. Magnetic read-write heads arranged on a moving actuator arm read and write data on to the surfaces.
What is the difference between Hard Disk and the Hard Disk Drive?
Hard Disk is a secondary storage device using magnetic coated disks to store the data. (The device as a complete unit is known as the HDD or Hard Disk Drive). The disks on which the data is written is known as the Hard Disks.