Tag Archives: Solid State Drive

What are Flash SSDs?

Earlier we used traditional hard disk drives in our computers. These were mechanically spinning magnetic disks with read-write heads. Nowadays, we use SSD or Solid-State Drives that have no moving parts. SSDs can retain data once it is saved without power, as they use NAND flash memory. To increase the data density, the NAND chips are multilayered. That means they can hold upwards of one bit of information per cell. SSDs using multilayered chips are named single-, multi-, triple-, quad-, and penta-level SSDs, according to the number of bits each cell can hold.

Multilayered SSDs have their own advantages and shortcomings and can range from speed to price to reliability. For instance, SLC or Single Level Cells have a lifespan measured in program/erase cycles of about 50,000 to 100,000 and can withstand high-intensity write operations.

MLCs or multi-level cells with two bits per cell can expect a lifespan of about 10,000 cycles and are mostly suitable for enterprise data centers.

TLCs or triple-level cells with three bits per cell can expect a lifespan of about 3,000 cycles and are useful for digital consumer products.

QLCs or quad-level cells with four bits per cell can expect a lifespan of about 2,000 cycles and are suitable for read-heavy operations, streaming media, and content delivery applications.

No data is available for the lifespan of PLCs or penta-level cells with five bits per cell. These SSDs are suitable for long-term storage of data such as in data archives.

Flash SSDs have revolutionized the storage of enterprise data in all its forms. They have enabled faster boot times and the application starts on PCs and mobile devices. They have facilitated the blistering performance of storage arrays in workloads like business analytics. In most performance metrics, flash SSDs have far outshone the older hard disk drives.

Speed aside, flash SSDs offer additional benefits. They are far more durable while being less susceptible to damage from abrupt physical shocks and movements, as compared to the traditional HDDs. Additionally, they use much less power to operate. Even though they cost more than the HDDs per gigabyte, the improved performance of SSDs overcomes their higher expense for most applications.

Flash SSDs store data in their memory cells using a technique called FGT or Floating Gate Metal Oxide Field Effect Transistors that can store a binary 0 or 1. With two gates, each FGT behaves like an electrical switch with current flowing between two points. NAND flash is named so as it uses NOT-AND logic gates. Power is not necessary to retain data in the flash cells, as, in the absence of power, the FGT provides the electrical charge for maintaining the data intact in the memory cells.

Flash SSDs are solid state, meaning they have no mechanical part to wear out. However, SSDs can nonetheless fail. One measure of SSDs is the lifespan or the number of program/erase cycles that a drive can complete before its degradation and failure. This is overcome by using wear-leveling technology, whereby the life of the SSD is prolonged by evenly distributing the program/erase cycle across the total NAND cells in the drive.

Solid State Drives – Why Are They So Fast?

For most people, an HDD or hard disk drive inside their computer is the flat broad box that stores their Operating System, files, documents, and other essentials. So far, not many users were aware of the inner workings of their HDD. Lately, with speeds of computers going up many folds, people have started looking at alternatives for the HDD – the SSD or the Solid State Drive.

Whatever else you change in your computer system, the general experience remains the same. For example, you may get a new display, add more RAM or install a new graphics card. Barring a few moments of exhilaration, you do not experience the constant euphoria that you get when you replace your regular HDD with an SSD.

An SSD suddenly transforms your computer into a high-speed demon. Additionally, you get this feeling every time you use the computer. Even if you do not realize this increase in speed with an SSD, you will appreciate it as soon as you have to revert to operating a computer with a regular HDD. It is truly amazing the way this new technology is helping to transform our computer experience.

To understand the functioning of SSDs, it is necessary to know the computer’s inner structure or architecture regarding its memory. A computer’s memory architecture is actually made up of three sections: the cache, the temporary memory and the actual memory storage itself.

The CPU or the Central Processing Unit of a computer is intimately connected to the cache memory and accesses it almost instantaneously. As the computer operates, the CPU uses the cache memory as a sort of scratch pad for all its interim calculations and procedures.

The temporary memory, also known as the RAM or Random Access Memory of a computer is the place where the CPU stores information related to all the active programs and running processes. Although the CPU can access the RAM at high speeds, the access is slower than that for cache memory.

For permanent storage, your computer uses the memory within the HDD or the SSD. These may be programs, documents, configuration files, movie files, songs, and many more. Unlike cache and RAM, an HDD or an SSD retains its contents even when the computer has been shut down.

When people replace their HDD with an SSD, their computer operates at a higher speed even when they have not updated their cache or RAM. This is fundamentally because of the difference in the way of working of an HDD and an SSD.

An HDD is essentially an electromagnetic device. Inside, there is a motor to spin the several magnetic platters stacked one on top of the other. Before the CPU can read data from the magnetic plates, they have to spin until the right sector comes under the reading heads, which then move in to read from the exact location. All this mechanical movement takes time.

On the other hand, the SSD, being an all-electronic device, involves no mechanical movements. It uses a grid of electrical cells to store and retrieve data. Moreover, these cells are further separated into sections called pages. Further, pages are clumped together to form blocks. All this contributes to the fantastic speed of an SSD.