Difference Between Hard Disk Drive (HDD) And Solid State Drive (SSD)


What Is a Hard Disk Drive (HDD)?

hard disk drive (HDD), hard diskhard drive, or fixed disk is an electro-mechanical data storage device that stores and retrieves digital data using magnetic storage and one or more rigid rapidly rotating 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.

Data is accessed in a random-access manner, meaning that individual blocks of data can be stored and retrieved in any order. HDDs are a type of non-volatile storage, retaining stored data even when powered off. Modern HDDs are typically in the form of a small rectangular box.

In other words, HDD is a data storage device that lives inside the computer. It has spinning disks inside where data is stored magnetically. The HDD has an arm with several “heads” (transducers) that read and write data on the disk. It is similar to how a turntable record player works, with an LP record (hard disk) and a needle on an arm (transducers). The arm moves the heads across the surface of the disk to access different data.

HDDs are considered a legacy technology, meaning they’ve been around longer than SSDs. In general, they are lower in cost and are practical for data that does not need to be accessed frequently, such as backups of photos, videos or business files. They are available in two common form factors: 2.5 inch (commonly used in laptops) and 3.5 inch (desktop computers).

HDDs are usually installed inside mobile devices, desktop computers, consumer electronics and enterprise storage arrays in data centers. They store Operating systems, software programs and other files using magnetic disks.

Also Read: Difference Between DVD And CD

What is a Solid-State Drive (SSD)?

solid-state drive (SSD) is a solid-state storage device that uses integrated circuit assemblies to store data persistently, typically using flash memory, and functioning as secondary storage in the hierarchy of computer storage. It is also sometimes referred to as a semiconductor storage device, a solid-state device or a solid-state disk, even though SSDs lack the physical spinning disks and movable read-write heads used in hard disk drives and floppy disks.

A solid-state drive (SSD) is a new generation of storage device used in computers. Due to use of flash-based memory, it is much faster than a traditional mechanical hard disk. SSDs use three main types of memory: single-, multi- and triple-level cells. Single-level cells can hold one bit of data at a time — a one or zero.

SSDs read and write data to an underlying set of interconnected flash memory chips. These chips use floating gate transistors (FGTs) to hold an electrical charge, which enables the SSD to store data even when it is not connected to a power source. Each FGT contains a single bit of data, designated either as a 1 for a charged cell or a 0 if the cell has no electrical charge.

SSDs are more expensive than HDDs per amount of storage (in gigabytes (GB) and terabytes (TB)), but the gap is closing as SSD prices decline at a faster pace that HDD prices year over year.

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Difference Between SDD And HDD In Tabular Form

Components HDDs contains moving parts- a motor-driven spindle that holds one or more flat circular disks (called platters) coated with a thin layer of magnetic material. Read-and-write heads are positioned on top of the disks; all this is encased in a metal case. SSD has no moving parts; it is essentially a memory chip. It is interconnected, integrated circuits (ICs) with an interface connector. There are three basic components- controller, cache and capacitor.
Read & Write Time HDD has a slower speed for reading and writing data. SSD is faster at reading and writing data.
Moving Parts The HDD has moving part and magnetic platters. With more uses they are prone to fail. The SDD drive has no moving parts. With more uses they are less likely to fail.
Fragmentation Over a longer period time and with larger files stored on an HDD, there is a high chance of fragmentation. Fragmentation doesn’t occur on an SDD drive.
Vibration Vibration is common with HDD due to spinning platters. SSD does vibrate due to absence of spinning parts.
File copying Speed In HDD, the speed of copying is usually 200 MB/s to 550 MB/s for cutting edge drives.   In SDD, the speed of copying is usually 50 MB/s to 120 MB/s.
Cost HDD generally costs cheaper than SSDs.   SSDs are generally expensive.
Heat HDD generates a lot of heat which can easily damage the electronic parts of the hard disk over the time. SSD does not generate heat.
Power Consumption HDD consumes more power due to spinning parts. The SSD consumes less power than the HDD.
Size They are available in 3.5’’ and 2.5’’ size for desktops and laptops. They are available in 2.5’’, 1.8‘’ and 1.0’’ increasing the available space in a computer, especially desktop or server.
Operating System Boot Time Its average boot-up time is 30-40 seconds. Its average boot-up time is 10-13 seconds.
Reliability HDDs have moving parts and are subject to potential mechanical failures from wear and tear. SSDs have no moving parts to fail mechanically.
Weight HDDs are heavier than SSDs. SSDs are lighter because they do not have the rotating disks, spindle and motor.
Noise HDDs generates noise due to rotating platters. SSDs do not generate noise.
Latency HDD has higher latency, longer read/write times, and supports fewer IOPs (input-output operations per second) compared to SSD. SSD has lower latency, faster read/writes, and supports more IOPs (input-output operations per second) compared to HDD.
Effect of Magnetism Magnets have a lot of influence on HDDs to a point that data can completely be erased. SSD is safe from any type of magnetism effect.

Advantages of SSD over HDD

  • The solid state drive uses flash memory to store data, which provides a better reliability and efficacy over hard disk drives.
  • SSD has access speed of 35 to 100 micro-seconds which delivers 100 times the performance of HDDs.
  • SSDs are more resistant and durable. 
  • Since an SSD has no moving parts, it needs less power to operate compared to an HDD with a magnetic spinning disk. 
  • Their smaller size allows SSDs to weigh less than larger HDDs with their magnetic heads and metallic disks. 
  • SSDs are easy to install.

Advantages of HDD

  • It provides a large storage capacity.
  • The stored items are not lost, even if the computer is shut down.
  • It is fixed inside the computer so it can’t be lost.
  • Computers can communicate with them easily.
  • It can store data like text documents, images, videos, etc.
  • HDD device can store operating system files and software related files.
  • It sizes very small, and it is portable in use.
  • They are cheaper compared to SSD.

Disadvantages of SSDs

  • Consumer-grade SSDs are more expensive than consumer-grade hard drives.
  • Due to the unique file system structure of an SSD, data extraction can be an extremely difficult and lengthy process.
  • Because the data recovery process is so difficult and takes so long, it can be quite expensive.
  • The memory chips in an SSD have a limited number of write cycles, which can lead to unrecoverable data loss.
  • If the controller chip, memory cache, or one of the NAND type memory chips has been physically damaged, your data may be completely inaccessible.

Disadvantages of HDD

  • Relies on moving parts.
  • The disk surface can be damaged.
  • Heavy power consumption.
  • It is noisy.
  • Slower read and write speed than RAM.
  • Slower to access than hard disk.
  • It is expensive.
  • The regular head can crash and damage the surface of the disk.
  • It is slower than IAS.
  • If a hard disk is crashes and computer do not work and your data will lose.
  • This disk was inside in computer so it can not easily transfer another computer.
  • If it eventually fails, the whole computer stops working at the same moment or at that time.