SATA Hard Drive Vs. Solid State

by Shea Laverty

Serial Advanced Technology Attachment (SATA) hard drives are a widely used computer storage medium. Often employed as the main storage device for both desktop and laptop computers, SATA drives face increasing competition from solid-state drives (SSDs). Despite the fact that both accomplish the same function, SATA drives and SSDs have key differences that may affect purchasing decisions, as well as how the drives are used.

SATA Drives

SATA drives are complex devices with moving parts. Inside a SATA's casing, a flat, circular disk called a platter sits atop a motorized spindle. The platter is made from non-magnetic material, thinly coated with a magnetic substance and layer of carbon to protect it's surface from damage. The spindle spins the platter at high speeds, while an actuator arm magnetizes areas of the surface using read and write heads. The magnetized areas store information written to the drive.

Solid-State Drives

SSDs are essentially microchips with a memory system and controller, but no moving parts. SSDs come in two varieties: Dynamic Random Access Memory (DRAM) and Flash memory. DRAM drives operate similarly to RAM modules, which provide high speed but does not preserve previously added data (lacks data persistence) when the power is cut off. DRAM SSDs typically use an internal battery or an external AC/DC power source and a backup system to counteract the lack of data persistence. Flash memory doesn't require any power sources and maintains data persistence even without power. Flash SSDs tend to run more slowly than DRAM SSDs, however.

Wear

The moving parts in a SATA drive limit its lifespan. In perpetual motion when the drive is in use, these parts wear down over time and eventually wear out. SSDs have much longer lifespans, due to the lack of moving parts to create wear and tear.

Vulnerability

Hard impacts, shocks and vibrations can cause catastrophic damage to a SATA drive because of the moving parts. If the actuator arm directly strikes the platter, it can damage the surface and destroy data stored in the damaged regions. SATA drives also suffer in the presence of electromagnetism or radiation, because of the magnetic technology they use. With no moving elements, SSDs are considerably less vulnerable to impact, shocks or vibrations. They're also more resilient to radiation and electromagnetism because they don't use magnetic technology.

Power Consumption and Heat

The motorized parts in SATA drives require additional power. Reading and encoding data also requires power to magnetize the platter's surface. When the additional power couples with the heat that the moving parts generate, SATA drives give off enough heat to need a fan or other cooling system to prevent damage to the drive. SSDs use minimal power and feature no moving parts, so heat generation is minimal, as is the need for dissipating elements.

Noise

SATA drive platters can revolve at up to 15,000 rotations per minute (rpm), depending on the set speed for the disk. Coupled with other moving parts, along with the sound of the fan -- SATA drives can prove noisy. This is especially true when the system puts a high demand on the drive, prompting the fan to run harder and prevent overheating. Since SSDs have no moving parts and minimal cooling systems, they produce little sound.

Cost

As of June 2011, SATA drives cost considerably less than their SSD counterparts. SSD technology is still not as widespread as SATA, resulting in higher retail costs. Prices should become more competitive as SSDs continue to gain wider market-share and are produced in greater numbers.

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