Mechanism and type of SSD (Solid State Drive)

1. What is SSD?

SSD is an abbreviation for Solid State Drive, which is a storage device similar to HDD (hard disk).

The difference from HDD is that it is a drive (storage medium) that uses "NAND flash memory ". Simply put, SSDs are categorized as storage media similar to SD cards and USB sticks.

The role of SSD is the same as that of HDD, but it has the advantages of being more shock-resistant and faster than HDD. Furthermore, in recent years, the price has been reduced and the capacity has been increased, so it is rapidly becoming widespread.

2. What's inside the SSD?

SSDs are used in the same way as HDDs, but their structure is completely different.

HDDs read and write data by moving parts such as magnetic heads and spindle motors, but SSDs do not have "physically driven parts". Therefore, SSDs are more resistant to vibrations than HDDs and are less likely to cause physical damage.

The main parts of SSD are explained below.

(1) Interface

It is a standard (connection port) that connects a personal computer and SSD. SSD connection standards are broadly divided into SATA (Serial ATA) and NVMe.

SATA: The same type of connection standard as HDD, which has rapidly become widespread since the 2000s.

NVMe: A new connection standard designed to optimize SSD usage. Since the standard is supposed to be installed on SSD, data transfer can be faster than SATA connection.

(2) Housing

It is the exterior of SSD. Currently, the 2.5-inch (6.35 cm) size is the mainstream, and 1.8-inch products are also on sale.

(3) NAND memory controller

A part that controls the reading of data. It is the heart of SSD.

(4) Cache memory

It is a small-capacity, high-speed memory that temporarily keeps data.

(5) NAND flash memory chip

The data will be saved here.

By the way, the same NAND flash memory is used in our familiar devices such as smartphones.

3. How is the data saved / deleted?

SSD writes data to memory via a controller.

Note that SSD memory has a limited number of rewrites, and if access is concentrated on a specific memory cell (the smallest unit for recording memory data), deterioration will accelerate.

Therefore, the SSD controller prevents deterioration and extends the service life by distributing the cells to be written so that the writing is not concentrated in the same area.

(Unlike HDD, SSD stores data separately)

So how exactly is the data written to memory?

From here, we will explain how data is written to memory.

First, the "NAND flash memory" mounted on the SSD saves and erases data by moving electrons between the three internal layers.

There is an electron storage area in the "floating gate", which is in the middle of the three layers, and the number of electrons stored in this area is the true identity of the "recorded data".

The membranes above and below the "floating gate" are normally "insulated" and do not allow electrons to leak out.

However, the "tunnel oxide film" under the "floating gate" does not insulate only when saving / deleting data, and allows electrons to pass through.

Data storage mechanism

When the "tunnel oxide film" is no longer an insulating film by applying a high voltage, electrons are stored in the "floating gate"

Data erasure mechanism

By applying a voltage "opposite" to when saving data, electrons are removed from the "floating gate" in the central layer.

What if data is lost?

There are third party software which are called data recovery software that will be very helpful for you in recovering your lost data. Data are recovered easily and in less time. You don’t have to take anyone’s help as it super easy to use and it will recover all your data without damaging them.