SSDs or solid state drives are taking the world by storm and for good reason. Anyone who’s used them will tell you how they’ve been blown away by their performance. If you are still using a mechanical disk on a multi-core machine with oodles of RAM, we can tell you for a fact that you haven’t experienced the full computing prowess of your rig.
On virtually all modern machines with traditional hard disks, the biggest bottleneck to system performance is disk access. SSDs remove that bottleneck and optimize the read and write operations to allow you to experience the full potential of your computer.
But SSD isn’t a one-size-fits-all solution. Vendors like WD or Kioxia, for instance, have a portfolio of several dozen SSDs. Before you can choose the right SSD for your computer, you must understand the various factors that are at play.
What is an SSD?
If you were to crack open a SSD and look under its hood so to speak, you’ll notice that an SSD is made up of three main components.
There’s the NAND flash, which is the workhorse of an SSD. It’s where the actual data is stored. The NAND flash in turn is made up of several blocks of non-volatile memory that do not require power to store the data. Then there’s a controller, which is the brains of the operation. It’s an embedded processor that contains the firmware to manage the read and write tasks of the SSD.
In addition to these two crucial components, there’s also another optional component. Many SSDs will also have some amount of volatile DDR memory that is used to cache information. This essentially helps further boost the write speed of the SSD.
SSD manufacturers tinker with these three essential ingredients to cook up all sorts of SSDs to address various use cases.
For instance, the Samsung 970 EVO has different sized caches for different sized disks. The 250/500GB disk has a 512MB cache, the 1TB version has a 1GB cache, while the 2TB disk is equipped with a 2GB cache. Similarly, while the 970 EVO uses the Samsung Phoenix Controller, the 860 EVO uses the Samsung MJX Controller.
Type of Flash memory
The main component of an SSD is the NAND flash and as we’ve mentioned earlier it’s made up of small memory cells that store the actual data in the form of bits.
The number of bits stored in a cell is one of the main distinguishing criteria between SSDs. In fact, the number of bits also helps determine whether an SSD is meant for enterprise use or for the end users.
Broadly speaking, SSDs can be classified into four types based on the number of bits they can pack.
There’s Single-Level Cell (SLC) that as the name suggests can store only a single bit per cell. SLC is the most basic of the lot, and also the fastest and most expensive, which is why they are the best choice for enterprise use.
The Multi-Level Cell (MLC) stores two bits in every cell. This helps reduce manufacturing costs, but without hampering the performance and durability too much. Due to this trade-off, MLC SSDs are suitable for price-conscious enterprise users, and even professional end-users.
Another type of NAND flash that’s designed for end-users is the Triple-Level Cell (TLC) that can accommodate three bits per cell. Samsung came out with the SSD 840 series, which featured TLC NAND flash, in 2012. It was a significant release as it helped change the popular perception that TLC NAND flash cannot be both performant and reliable.
Finally, there’s Quad-Level Cell (QLC) SSDs that house four bits per cell. When they were first introduced, they weren’t considered to be reliable enough even for end-users. Again, it took innovation from Samsung to make QLC SSDs a usable option for price sensitive users. One of Samsung’s latest 4-bit SSDs is the 870 QVO, which is perhaps the best affordable high capacity SSD for consumers.
Types of SSDs
While the number of cells in the NAND flash mainly helps determine the performance of the drive (which has a bearing on the cost of the drive), there are two other parameters that you need to be familiar with in order to select the right SSD for you.
First up is the connector type. The first generation of SSDs connected over the existing SATA connectors that were used to plug the traditional hard disks. However, with a maximum theoretical transfer speed of 600MB/s, SATA was unable to keep pace with the speeds of SSDs that range in multiple GB/s.
Newer connectors were quickly introduced to help maximise the performance gains of SSDs. The most popular of these, especially for consumers, is the PCI Express (PCIe) and M.2.
The type of connector helps determine the form factor or the physical attributes of the drive. SSDs can be classified into three main types based on their physical characteristics.
The 2.5-inch Serial ATA (SATA) SSDs are reminiscent of traditional hard disks and are one of the most common types of SSDs on offer and can connect using the existing SATA cables in your PC. If your machine has a 2.5-inch hard drive bay and a spare SATA connector, you can simply plug them in and you’re good to go. These are the preferred means of switching to SSDs for older computers that lack the more recent connectors.
If you have a recent desktop though it’ll probably have a PCIe slot. If it does you should use the Add-in Card (AIC) SSD. These drives are much faster since they operate over the newer and faster PCIe interface. AIC drives plug into the slots on a desktop’s motherboard that are commonly used for graphics cards.
Most modern laptops now have the M.2 slots for mounting SSDs. M.2 SSDs resemble a RAM stick in shape, but are only about the size of a gum-stick. M.2 drives have become the standard for installing SSDs in laptops.
Why are there different SSDs?
Just as you can’t recommend the same PC for every user, you can’t have a SSD that’ll work for everyone. One of the biggest determinants is usually price, with some consumers being more price conscious than others. In stark contrast are the consumers that don’t mind spending more money to get disks that are better suited for their performance oriented tasks.
This is why manufacturers like Samsung have an extensive portfolio of drives to meet the requirements of all types of consumers with their different needs.
Furthermore, being a global vendor Samsung also has to cater to the sensibilities of certain markets. Based on individual preferences, some markets respond better to cheaper disks, while others prefer to have the latest.
SSDs are available in several different sizes to satisfy all kinds of use cases. When they were first introduced, SSDs of 128GB were pitched to consumers for installing their operating systems and key applications. The 256GB and the 512GB SSDs allow more flexibility and will fit most budgets. If price isn’t a concern though, you also have SSDs that offer storage of 1TB and more, all the way to 8TB.
