Everything you have to know about SSDs

Solid State Drive architecture and working principles explained

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Everything you have to know about SSDs

If you have ever wondered how an SSD or Solid State Drive works, this article is made exactly for you. These modern super-storage devices are used everywhere. The modern commercial use of SSDs began with 2.5-inch form factor SATA drives, nowadays we not only use these drives in our systems as primary drives in a combination with hard disk drive but also as standalone drives.

The SSD technology and their chips keep getting more and more advanced. You can get a super slim M.2 NVME SSDs that are super light, compact and offer superb performance when compared to conventional hard drives and even with SATA SSDs.

Related: Best M.2 SSDsThe Fastest SSD and Best Solid State Drive (SSD) Brands

As one of SSD biggest advantages, people usually mention their build – it features no mechanical or moving parts. This means they can last much, much longer and are more durable.

A Solid State Drive isn’t an easy device, it contains many important parts and components to run properly. In a picture below you can see a simple SSD layout with all its most important components:
SSD controller image

A brief look into SSD history

Before we jump into SSD working principle and its main technical specifications, let’s take a small look into SSD history. Often you can learn a lot just from reading articles about scientists and inventors of things.

A Solid State Drive has its origins dated back in the 1950s. Back then something similar to modern SSD was accomplished with two different technologies: card capacitor memory and magnetic core memory.

Then in the 1970s and 1980s, SSDs were used in semiconductor memory for supercomputers. This was done by such large companies like Amdahl, IBM, and Cray. At the end of the 1970s, a company called “General Instruments” made EAROM or electrically alterable ROM. It operated similarly to today’s NAND flash memory. (Read more about difference between RAM and ROM on our RAM vs ROM article). The next huge step was in 1978 when a company called Texas Memory Systems introduced a 16 kilobyte RAM SSD. It would be used by oil companies to acquire seismic data. So it all began.

20MB SSD for 1000$ in 1991

 

 

In 1991 you could buy a 20MB SSD for 1000$ (Now you cloud but two 1TB Samsung’s m.2 NVMe sticks and you would still be left with some money in your pocket.

 

SSD Architecture

As we already know, SSD consists of two main key components – controller and memory to store data. The first memory for SSD was DRAM volatile memory, now the most common are NAND nonvolatile memory.

ssd architecture
Source: http://codecapsule.com/2014/02/12/coding-for-ssds-part-2-architecture-of-an-ssd-and-benchmarking/

Controller

Just like a hard disk drive or solid state drive, also SSD have to have a controller to store data. A controller is basically a processor that executes code. This code is responsible for the efficiency of storing data. SSD controller also performs such actions like encryption, read/write caching, wear leveling, error-correcting and much more. A controller plays a huge role when it comes to SSD performance.

Memory

There are two main types of flash-based memories SLS and MLC as well as NAND and NOR. This is another very important factor for SSD performance. NAND and NOR memory is a lot faster, but also more expensive than SLC or MLC memory. Yes, one SSD can be a lot faster than another.

Buffer or Cache

Despite having the main memory, SSD also uses a small amount of DRAM for cache purposes. Therefore, data is not permanently stored in DRAM.

Interface

When you have an SSD, you can attach or connect it to your computer in many ways. Below are most of them.

  • Serial attached SCSI (SAS, > 3.0 Gbit/s)
  • PCIe M.2 (>2GB/s)
  • Serial ATA (SATA, > 1.5 Gbit/s)
  • PCI Express (PCIe, > 2.0 Gbit/s)
  • Fibre Channel (> 200 Mbit/s) –
  • USB (> 1.5 Mbit/s)
  • Parallel ATA (IDE, > 26.4 Mbit/s)
  • (Parallel) SCSI (> 40 Mbit/s)

Final Words

Solid State Drive technology is evolving each year, SSDs get smaller and offer a lot more performance. We are sure that after about 5-10 years, all new computers will use an SSD as their main drive and hard drives will be in the past – only being used to store really massive amounts of data.

However, this means there will be many different types of SSDs that feature different controllers and memories. Some may be cheaper and some more expensive so just like HDDs, you will have to check for the best one you can buy. It won’t be like until now were having any kind of SSD means you have a super fast drive.

 

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