{"id":387,"date":"2020-04-08T00:04:36","date_gmt":"2020-04-07T22:04:36","guid":{"rendered":"https:\/\/tekmart.co.za\/t-blog\/?p=387"},"modified":"2020-04-08T00:07:29","modified_gmt":"2020-04-07T22:07:29","slug":"what-are-multi-layer-ssds-slc-mlc-tlc-qlc-and-plc-an-explanation","status":"publish","type":"post","link":"https:\/\/tekmart.co.za\/t-blog\/what-are-multi-layer-ssds-slc-mlc-tlc-qlc-and-plc-an-explanation\/","title":{"rendered":"What Are Multi-Layer SSDs-SLC, MLC, TLC, QLC, and PLC?- An explanation…"},"content":{"rendered":"Reading Time-approximately:<\/span> 4<\/span> minutes<\/span><\/span>\t\t
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Solid-state drives\u00a0improve the performance of aging computers and turn newer PCs into speed machines. But, when you shop for one, you\u2019re bombarded with terms, like SLC, SATA III,\u00a0NVMe, and\u00a0M.2. What does it all mean? An expert takes a look!<\/strong><\/h2>\n\n\n\n

Post courtesy of:<\/p>\n\n\n\n

Ian Paul from HowtoGeek.com<\/p>\n\n\n\n

IAN PAUL<\/a>@ianpaul<\/a><\/p>\n\n\n\n

It\u2019s All About the Cells !<\/h2>\n\n\n\n

Current SSDs use NAND flash storage, the building blocks of which is the memory cell. These are the base units onto which data is written in an SSD. Each memory cell accepts a certain amount of bits, which are registered on the storage device as 1 or 0.<\/p>\n\n\n\n

Single-Level Cell (SLC) SSDs<\/strong><\/h2>\n\n\n\n

The most basic type of SSD is the single-level cell (SLC) SSD. SLCs accept one bit per memory cell. That\u2019s not a lot, but it has some advantages. First, SLCs are the fastest type of SSD. They\u2019re also more durable and less error-prone, so they\u2019re considered more reliable than other SSDs.<\/p>\n\n\n\n

SLCs are popular in enterprise environments where data loss is less tolerable, and durability is key. SLCs tend to be more expensive, and they aren\u2019t typically available for consumers. For example, I found a 128 GB enterprise SLC SSD on Amazon that cost the same as a 1 TB, consumer-level SSD with TLC NAND.<\/p>\n\n\n\n

If you do see a consumer SLC SSD, it probably has a different type of NAND and an SLC cache to improve performance.<\/p>\n\n\n\n

Multi-Level Cell (MLC) SSDs<\/strong><\/h2>\n\n\n\n
\"The
Intel\u2019s S3520 Series MLC SSD.\u00a0Intel<\/strong><\/figcaption><\/figure>\n\n\n\n

The \u201cmulti-\u201d in multi-level cell (MLC) SSDs isn\u2019t particularly accurate. They only store two bits per cell, which isn\u2019t very \u201cmulti-,\u201d but, sometimes, technology naming schemes aren\u2019t always forward-looking.<\/p>\n\n\n\n

MLCs are a bit slower than SLCs because it takes more time to write two bits onto a cell than just one. They also take a hit in durability and reliability because data is written to the NAND flash more often than with an SLC.<\/p>\n\n\n\n

Nevertheless, MLCs are solid SSDs. Their capacities aren\u2019t as high as other SSD types, but you can find a 1 TB MLC SSD out there.<\/p>\n\n\n\n

Triple-Layer Cell (TLC) SSDs<\/strong><\/h2>\n\n\n\n

As its name implies, TLC SSDs write three bits to each cell. At this writing, TLCs are the most common type of SSD.<\/p>\n\n\n\n

They pack more capacity than SLC and MLC drives into a smaller package, but sacrifice relative speed, reliability, and durability. That doesn\u2019t mean TLC drives are bad. In fact, they\u2019re probably your best bet right now\u2014especially if you\u2019re hunting for a deal.<\/p>\n\n\n\n

Don\u2019t let the notion of less durability get you down; TLC SSDs usually last for several years.<\/p>\n\n\n\n

Terabytes Written (TBWs)<\/strong><\/h2>\n\n\n\n

Typically, SSD durability is expressed as TBW (terabytes written). This is the number of terabytes that can be written to the drive before it fails.<\/p>\n\n\n\n

The 500 GB model of the Samsung 860 Evo (a popular SSD from a few years ago) has a TBW rating of 600; the 1 TB model is 1,200 TBW. That\u2019s a whole lot of data, so a drive like this should serve you for many years.<\/p>\n\n\n\n

TBWs are also \u201csafe level\u201d estimates; SSDs commonly exceed these limits. To be on the safe side, though, make sure you back up to minimize data loss\u2014especially with older drives.<\/p>\n\n\n\n

Quad-Level Cell (QLC) SSDs<\/strong><\/h2>\n\n\n\n
\"An
Intel\u2019s 660p was an early consumer QLC SSD released in 2018.\u00a0Intel<\/strong><\/figcaption><\/figure>\n\n\n\n

Quad-level cell (QLC) drives can write four bits per cell. Are you sensing a pattern at this point?<\/p>\n\n\n\n

QLC NAND can pack a whole lot more data than other types, but, right now, QLC drives take a big hit on drive performance. This is especially true when the cache runs out during large file transfers (40 GB or higher). This might be a short-term problem, as manufacturers try to optimize QLCs.<\/p>\n\n\n\n

Durability is also a concern, though. The budget-level Crucial P1 QLC NVMe drive only has a 100 TBW rating on the 500 GB model, and only 200 TBW on the 1 TB. That\u2019s quite a drop from the TLC, but it\u2019s still good enough for home use.<\/p>\n\n\n\n

Penta-Level Cell (PLC) SSDs<\/strong><\/h2>\n\n\n\n

PLC SSDs, which can write 5 bits per cell, don\u2019t exist yet for consumers, but they\u2019re on the way.\u00a0Toshiba mentioned PLC drives\u00a0in late August 2019, and\u00a0Intel\u00a0the following month. PLC drives should be able to pack even more capacity into SSDs. However, they\u2019ll have the same problems as TLCs and QLCs when it comes to durability and performance.<\/p>\n\n\n\n

We advise you wait until reviews come out before you purchase an early PLC SSD. Also, check out the TBW ratings to see how long they\u2019ll last, and how the TBW breaks down in real-world terms.<\/p>\n\n\n\n

For example, the QLC drive we mentioned above has a lower TBW rating, but it works out to about 54 GB written per day over five years. No one writes that much data at home, so you could expect that drive to last a long time, despite its lower TBW rating.<\/p>\n\n\n\n

Other SSD Terms<\/strong><\/h2>\n\n\n\n
\"A
An early example of Samsung\u2019s 3D NAND flash. Samsung<\/figcaption><\/figure>\n\n\n\n

Those are the basic types of NAND flash, but here are a few more terms it might help you to know:<\/p>\n\n\n\n