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In this article we’ll explain the difference between HDD and SSD, and show you the advantages and disadvantages of both technologies.

A hard disk (fixed disk, hard disk drive or just hard drive) is a data storage device used for nonvolatile data storage, by using one or more platters (hard rapidly rotating disks) with magnetic heads arranged on a moving actuator arm to read and write data to the surfaces. “Nonvolatile” means that an HDD is a persistent storage option – it retains
data when the operating system is shut down.

A solid-state drive (or solid-state disk) is a data storage device that uses integrated circuit assemblies as memory to store data persistently. Although referred to as a “disk”, an SSD has no mechanical (moving) components – it contains no actual disk, nor a drive motor to spin a disk.

difference between HDD and SSD

Generally, both SSDs and HDDs can do the same job: they can boot your operating system, store your applications, and store your personal files (pictures, movies and other documents). But what type of storage should you choose, having in mind pros and cons of both technologies? The question is, what’s the difference between HDD and SSD, and why would you get one over the other? This article should give you answers and some guidelines, and differences will be presented in an alphabetical order.

What is the difference between HDD and SSD?

Capacity

Generally, the capacity of an SSD on an average computer is smaller than that of a HDD, due to the higher price of an SSD; generally, users’ capacity requirements are becoming larger, so you can find SSDs with the capacity of 4TB (and they are very expensive), but users rarely spend that sort of money for an SSD – the general PC configuration trend is to have a low capacity SSD for the operating system and applications, and higher capacity HDD for data, backup images and other things. Wikipedia states that in 2013 the maximum capacity for an SSD was 2 TB, but cheaper 128 – 512 GB SSDs were more common on an average computer. When it comes to HDDs, in 2014 the maximum capacity of a HDD was 8 TB. So, if you are looking for a device with large and “pocket friendly” capacity, choose HDD.

Fragmentation

When it comes to HDDs, sooner or later disk fragmentation occurs, and the fragmentation level depends on the operating system (or file system, to be precise) and user habits; Linux file systems are traditionally more resistant to fragmentation. For better HDD performance on Windows, a disk defragmentation is recommended. Anyway, SSDs don’t suffer from this fragmentation performance loss: SSDs don’t care where the data is stored on its chips, since there’s no physical read head. Files may be scattered anywhere with no performance loss. This is the advantage of SSDs – flash cells are being accessed in real time.

Noise

Since they have no moving parts, SSDs are very quiet devices. On the other hand, a HDD has moving parts (rotating disks, moving hand…) which result in higher levels of noise. SSDs are the winner in this field.

Price

Hard disk drives are dinosaurs of the digital age; they are an old and established technology, so they will remain less expensive than SSDs for the near future. SSDs are more expensive than HDDs in terms of dollar per GB. For example, for the same capacity of 1 TB and and form factor 2.5-inch drive, you’ll pay about:

  • HDD: $60 – $75,
  • SSD: $430 -$500.

You can find hybrid devices that have both technologies combined, such as 1TB Seagate devices, that combine a hard disk and the low capacity (i.e. 8GB) SSD. Anyway, HDDs win the price race.

Reliability

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As we’ve previously mentioned, an SSD doesn’t have moving parts nor disks, and the data processing rate is increased by over 80%, but are they reliable devices for data storage  ?

It’s well known that all electrical devices from processors to memory are based on silicon chips and boards and their technology is more sophisticated every year, so they become smaller and need lower voltage for them to work. Some memory almost uses their static electricity to manage data. However, Silicon is highly affected by radiation exposure and its crystal structure is easily broken if it’s not well protected. Therefore, all these devices are sensitive to electrical, electromagnetic and solar radiation and discharge. Although well packaged and protected, your SSD can easily die if it gets any non-standard electrical impulse or an impulse greater than 5V of positive electric charge (or even worse – negative electric charge), resulting in data loss.

When faced with above mentioned impulses a HDD would also stop working but it’s way easier to recover your data. Since your data is located on platters, you can mount electronics (if the old one died out) from the other hard disk (it must be the same type) and recover your data even after 10-15 years since the last use of the HDD. We recommend sending damaged HDD to computer service to recover your data.

Moreover, each block of a flash-based SSD can only be erased (and therefore written) a limited number of times before it fails. These flash memory chips differ from the flash memory in USB flash drives in the type and speed of the memory. The flash memory in SSDs is faster and more reliable than the flash memory in USB thumb drives, but also suffers from this limitation.

Shock resistance

Since the HDD’s heads floating above rapidly rotating platters are susceptible to shock and vibration, HDDs are not really highly shock resistant while working. To make this  clearer, watch this video clip – “Hard drive teardown“:

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