Wednesday, August 5, 2015

Solid state drive (SSD) will soon phase out the traditional hard disk drive (HDD)

Flash memory devices that store computer data using NAND memory chips is gradually dominating the data storage medium.

We have just seen how soon the USB thumb drives replaced the optical discs (CDR, DVDR, Blueray, ...) to become the major removable storage medium nowadays. I believe we will soon see the SSD phasing out the traditional HDD to become the major internal storage medium.

In fact, flash memory is already the data storage medium in mobile devices and slim ultrabook computers nowadays.

Traditional HDD stores data in spinning magnetic discs, and the data read/write is performed with a movable r/w head. Since there are moving parts, there will be wear and tear during operations, which limit down its lifespan. Also, it is fragile to drop or even large physical movement during operations, eg. if you shake your laptop with your hands while its HDD is busy operating, you'll probably cause  damage to the HDD, such as introducing some bad sectors.

The traditional HDD also access data much slower than SSD, which is its main disadvantage against SSD. However, HDD is cheaper to produce, and therefore carries a much cheaper price than SSD, and made available at generally higher storage capacity too.

So, the 2 main reasons why SSD hasn't replaced the HDD yet as of today, are:

  • Price
  • Available storage capacity
New NAND memory technology that evolves in 2014 will change the game plan. Now, manufacturers including Samsung, Toshiba, Intel, etc. have already come out with multi-layer 3D NAND memory chips, which stakes the flash memory cells vertically in 32 layers or even 48 layers, to achieve a 256 gigabits multilevel cell (MLC) and 384 gigabits triple-level cell (TLC) die that fit within a standard package.

It is said that this approach can greatly reduce the manufacturing cost, at the same time can make available higher storage capacity to SSD. With reduced price and comparable storage capacity with HDD, there is no more resistant for SSD to replace HDD as the major computer storage medium.

Advantages of SSD over HDD including:
  • Can package in smaller size
  • Less electricity consumption
  • Less heat produced during operation
  • High grade NAND can have a warranty period of 10 years, much longer than HDD
  • Much faster data access speed
  • More robust to drop or movement during operation

The diagram below is a Samsung 850 EVO SSD using the 3D V-NAND technology. You will soon find it inside the next generation of Apple MacBooks within the next couple of months.


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