Solid State Drive (SSD)[]
by Caroline Merkel
While functionally equal to a hard disk drive (HDD), SSDs are widely considered the storage capsules of the future. An HDD works via a spinning ("drive") arm (a la a record player) that reads data off of a "metal platter" with a magnetic coating that contains the saved data. SSDs perform the same functions, however they store data in a series interconnected flash memory chips, chips that are capable of retaining the data even when power is lost, as with the memory stored in RAM.
Solid State Drive (SSD) (left) vs. Hard Disk Drive (HDD) (right)
Brief History of Solid-State Drives
The concept of hard drive storage has existed nearly as long as computers themselves, however, SSDs have a much shorter history. SSDs were first popularized in the late 2000s, with the rise of netbooks (for more on netbooks, click here). The flash memory used in SSDs is a logical extension of bubble memory, a type of memory that doesn't require consistent power to retain the data stored. Early SSDs were molded to the motherboard, however, as computers developed with increased mobility and capability, SSDs became more portable (standardized at 2.5 inches), allowing the user to easily replace the HDD with an SSD. Storage capabilities have also increased greatly, from a mere 1GB of storage in 2007 to a 2.5-inch SSD with storage capacities topping out at 4TB today.
How Do Solid-State Drives Work?
With an HDD, the physical movement required by the drive arm results in a non-zero wait time. Even though the wait time might be measured in milliseconds, that is still a lengthy amount of time as compared to the speed of CPUs, which operates in nanoseconds. Therefore, it was always clear that HDDs would never match the CPU speeds. However, SSDs store data in a "pool of NAND flash," which allows the data to retain its charged state at all times (this is a non-volatile memory). NAND flash cells store data-charged, "0" electrons in a grid (commonly referred to as the "block"), and release the non-charged, "1" electrons. As a result of this system, and the SSD's technically static nature, it can operate at speeds far greater than the HDD.
Pros and Cons of Solid-State Drives
While SSDs generally work at a much faster rate than HDDs, there are reasons that explain and favor the continued use of HDDs in so many computers. HDDs remain reliable, while SSDs are notoriously susceptible to data rot and fundamental weakness, especially related to writing and erasure of data.
Price
SSDs are almost always more expensive than HDDs, in terms of dollar per gigabyte.
Speed
As mentioned above, this is the department in which SSDs truly outshine the traditional hard drive. If a PC is equipped with an SSD, it can boot far faster than an HDD-equipped computer. Boot-up, loading time, and file transfers are almost always faster with an SSD, a feature that is greatly valued for many PC owners.
Read/Write Capability
One downside to SSDs is their poor capability for continued reading and writing, along with the fact that writing on an SSD is a very different and much more complex process. SSDs cannot perform a write unless it has a freshly available erased page ready for use, while an HDD can read, write, and delete "in-place." As a result of this, and the deletion of data blocks over time (which are not really deleted by the SSD controller), SSDs tend to get slower and slower as they age, until finally they reach their maximum capacity of writes.
Longevity
HDDs have a continuous issue with longevity, as the physical nature of the drive causes it to wear out over a few years. While SSDs will eventually run out of writes, they are still capable of reading the data, and one is more likely to discard an SSD because it is outdated than because it began to have serious read/write errors. However, it is possible that SSDs will begin to "rot" into a read-only stage, after an extended period of time. And even when the drive is read-only, data rot may continue, until the NAND flash is forced to rewrite data (it seems, however, that this idea is more applicable in theory than reality). Thus, SSDs typically have greater longevity.
So, Which is Right For You?
If you use a ton of download and storage space, you may want to stick with a classic HDD. They come cheaper, and perform the same functions as an SSD.
If you value speed and durability, it might be worth the extra bucks to invest in an SSD. They are less susceptible to physical damage than HDDs, and the speed is a definite pro.
If you're just an average user, it's really up to you. Many laptops come with one drive or another installed in the system, and it's probably not worth it to take the time and effort to replace that. However, both will do the job just fine, and ultimately, it comes down to one's nitty gritty preferences.
Sources:
http://www.pcmag.com/article2/0,2817,2404258,00.asp
https://www.extremetech.com/extreme/210492-extremetech-explains-how-do-ssds-work
https://www.cnet.com/how-to/how-ssds-solid-state-drives-work-increase-lifespan/
http://techreport.com/review/24841/introducing-the-ssd-endurance-experiment