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Hard Disk Drive/ Solid State Drive Overview

A hard disk drive (HDD) is an old-school storage device that uses mechanical platters and a moving read/write head to access data. A solid-state drive (SSD) is a newer, faster type of device that stores data on instantly-accessible memory chips.

HDDs: An enclosure contains a series of platters covered by a ferromagnetic coating. The direction of the magnetization represents the individual bits. Data is read and written by a head (similar to the way vinyl record albums work) that moves extremely fast from one area of the disk to another. Since all of these pieces are “mechanical,” the hard disk is the slowest component of any computer – and the most fragile.
SSD: These newer types of disks store information on flash memory, which consists of individual memory cells storing bits that are instantly accessible by the controller.

How is a hard drive connected to a computer?

An internal hard drive is connected to the computer using by two means: a data cable to the motherboard and a power cable to the power supply.

Where is the hard drive found in the computer?

All primary computer hard drives are found inside a computer case and are attached to the computer motherboard using an ATA, SCSI, or SATA cable. Hard drives are powered by a connection to the PSU (power supply unit).

What are the sizes of hard drive?

The hard drive is often capable of storing more data than any other drive, but its size can vary depending on the type of drive and its age. Older hard drives had a storage size of several hundred MB (megabytes) to several GB (gigabytes). Newer hard drives have a storage size of several hundred gigabytes to several TB (terabytes). Each year, new and improved technology allows for increasing hard drive storage sizes.

How is data read and stored on a hard drive?

Data sent to and read from the hard drive is interpreted by the disk controller. This device tells the hard drive what to do and how to move its components. When the operating system needs to read or write information, it examines the hard drive's FAT (File Allocation Table) to determine file location and available write areas. Once they have been determined, the disk controller instructs the actuator to move the read/write arm and align the read/write head.

What kind of connection do solid state drive utilize?

SSDs have traditionally used the SATA connection, which has a theoretical maximum transfer rate of 750 MB per second. Newer generations of SSDs connect to the motherboard's PCIe connection, offering speeds of up to 1.5 GB per second. The PCIe m.2 connection standard, introduced in 2014, offers a maximum real-world throughput of approximately 4 GB/s.

What are the benefits of solid state drives?

No noise because of no moving parts.
Lower heat emission compared to hard drives.
Lower power consumption and as a result: Longer battery life for laptops.
Much more resistant to shock and vibration, making them less likely to fail from that.
Much lower latency (~0.07ms compared to 7-9ms).
Much higher transfer rates for reading and writing files in all type of scenarios.

How long do SSDs last?

Solid state drive technology’s lifespan depends on how it is being used. This is a major difference between SSDs and HDDs, as SSDs do have a finite life. There are only a limited number of program and erase cycles that an SSD can perform before it starts losing data. The level of use determines how long an SSD will last. With light use, it could take a decade or more for it to wear out, but more intense use means a faster burnout.

When are SSDs used?

They are always used over HDDs in applications that need drives that are small in size and that don’t demand a lot of power for usage. They are also preferable in applications that need high performance speeds. SSDs are also desirable for applications that need storage in rugged operating conditions. In addition to being tolerant of shock and vibration, SSDs function well in extreme temperatures and temperature fluctuations.