A solid-state drive (SSD) is a non-volatile computer storage device. This means that it stores permanent data that does not disappear when a device is turned off. It handles persistent data on an integrated circuit assembly, also described as solid-state flash memory. Usually, SSDs can replace standard hard disk drives (HDDs) as they cover the same functions, however, they also are significantly faster than the latter too.
Wherever a hard drive can work, an SSD can work too. Therefore, they can be used in PCs, laptops, digital cameras, digital music players, smartphones and tablets. Because of their speed, businesses have learnt to use the volatile element rather than hard disk drives, also due to their ability to handle heavy read and random workloads.
An HDD is formed by a spinning disk on a mechanical arm, called an actuator, and it reads and writes information using magnets. However, due to its mechanical nature, it is also more prone to breaking down. On the other hand, an SSD is not made of moving parts, but rather of a flash controller and NAND flash memory chips.
How does an SSD work?
Flash memory chips are made out of silicon, and they are used to read and write data. Usually, manufacturers can achieve different densities by stacking different chips in a grid.
The chips work thanks to floating gate transistors (FGTs) which emit an electrical charge, which keeps the SSD active even without a power source.
When it comes to memory, SSDs have three main types: single-level, multi-level and triple-level cells. The first kind can only hold one bit of data (1 or 0) at a time, making them the quickest and most efficient SSDs out there, as well as being the most expensive ones. The multi-level cells (MLCs), on the other hand, can hold two bits of data at a time, and they hold more storage space. However, since they process more information at once, their performance is also slower. The cheapest SSDs are the triple-level cells (TLCs) which, as the name suggests, can hold three bits of data in one cell. They usually are slower and less durable, though.
What are the different types of SSDs?
There are six main types of SSDs: solid-state drives, Peripheral Component Interconnect Express (PCle)-based flash, flash DIMMs, NVMe SSDs, NVMe-oF, and hybrid DRAM-flash storage.
The most basic model is the first, the solid-state drive. These SSDs have also the least amount of functions, and their flash devices connect via Serial Advanced Technology Attachment (SATA) or serial-attached SCSI (SAS). The PCle-based flash is the second-best thing since they offer more input-output operations per second, but they are less latent and less secure. This kind of flash is often used to connect graphic cards or high-performance hardware.
The NVMe SSDs stand for non-volatile memory express, and they offer higher speed of client-system connections and more solid state drives. Similarly to the PCle-based flash, they are also designed for high-performing computing equipment.
The last type, the hybrid DRAM-flash storage, is a dynamic random access memory (DRAM) channel configuration, which aims to mix the flash and server DRAM. As a hybrid element, they speed up the connection between application software and storage.
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