The magic of SSD explained

 

SSDs, or solid-state drives, are a type of storage device that use flash memory to store data. Unlike hard disk drives (HDDs), which have spinning disks and moving parts, SSDs have no mechanical components and are much faster, quieter, and more reliable. SSDs store data in clusters of memory cells called NAND flash, which can retain data even when the power is off. This makes SSDs non-volatile memory, unlike RAM, which is volatile and loses data when the power is off.

To read and write data, SSDs use a controller that communicates with the NAND flash cells. The controller also performs various functions such as wear leveling, garbage collection, error correction, and encryption. Wear leveling is a technique that distributes the write operations evenly across the cells to prevent some cells from wearing out faster than others. Garbage collection is a process that reclaims the space occupied by deleted or invalid data and prepares it for new writes. Error correction is a method that detects and corrects any errors or corruption in the data. Encryption is a feature that secures the data with a password or a key.

SSDs have many advantages over HDDs, such as:

• Faster performance: SSDs can access data much faster than HDDs, as they do not have to wait for the disks to spin or the heads to move. This results in faster boot times, application loading, file transfers, and overall system responsiveness.
• Lower power consumption: SSDs consume less power than HDDs, as they do not have any moving parts that generate heat and noise. This also makes them more suitable for laptops and mobile devices, as they extend the battery life and reduce the weight.
• Higher reliability: SSDs are more resistant to shock, vibration, temperature changes, and magnetic fields than HDDs, as they do not have any sensitive mechanical parts that can fail or break. This also makes them less prone to data loss or corruption.

However, SSDs also have some disadvantages, such as:

• Higher cost: SSDs are more expensive than HDDs per unit of storage capacity, as the flash memory technology is still relatively new and costly. However, the price gap between SSDs and HDDs is gradually narrowing as the technology improves and becomes more widespread.
• Limited lifespan: SSDs have a finite number of write cycles before they wear out and become unusable. This is because every time data is written to a cell, it erases and reprograms it, which gradually degrades its quality. However, modern SSDs have advanced wear leveling and error correction algorithms that extend their lifespan and prevent data loss.

There are different types of SSDs based on the interface and the form factor. The interface is how the SSD connects to the computer and determines the speed and performance of the SSD. The form factor is the size and shape of the SSD and affects the compatibility and portability of the SSD.

Some common types of SSDs are:

• SATA SSD: This is the most common type of SSD and uses the SATA interface, which is also used by HDDs. SATA SSDs have a standard 2.5-inch form factor and can fit in most laptops and desktops. SATA SSDs are more affordable than other types of SSDs, but they are also limited by the SATA bandwidth, which is 6 Gb/s.
• M.2 SATA SSD: This is a type of SSD that uses the SATA interface but has a smaller M.2 form factor, which is a thin card that can be inserted into a slot on the motherboard. M.2 SATA SSDs are more compact than 2.5-inch SATA SSDs, but they have the same speed and performance as SATA SSDs.
• M.2 PCIe SSD: This is a type of SSD that uses the PCIe interface, which is faster than the SATA interface. PCIe SSDs have an M.2 form factor and can be inserted into a slot on the motherboard. PCIe SSDs can achieve speeds up to 32 Gb/s, depending on the number of lanes they use.
• M.2 NVMe SSD: This is a type of SSD that uses the PCIe interface and a new protocol called NVMe, which is optimized for flash memory. NVMe SSDs have an M.2 form factor and can be inserted into a slot on the motherboard. NVMe SSDs are the fastest type of SSDs available, as they can reach speeds up to 64 Gb/s, depending on the number of lanes they use.
• mSATA SSD: This is a type of SSD that uses the SATA interface but has a smaller mSATA form factor, which is similar to a mini PCIe card. mSATA SSDs are usually found in laptops, tablets, or ultrabooks, where space is limited. mSATA SSDs have the same speed and performance as SATA SSDs.
• U.2 SSD: This is a type of SSD that uses the PCIe interface and has a 2.5-inch form factor, which is similar to a SATA SSD. U.2 SSDs are connected to the motherboard with a cable, unlike M.2 or mSATA SSDs, which are inserted into slots. U.2 SSDs can achieve speeds up to 32 Gb/s, depending on the number of lanes they use.

Things no one will tel you at the store or youtube...

SLC, MLC, TLC, QLC, and PLC are abbreviations for different types of SSDs based on how many bits of data they can store in each memory cell. The more bits per cell, the higher the capacity, but also the lower the speed and durability. Here is a brief explanation of each type:

• SLC (Single Level Cell): Each cell stores one bit of data. This makes them the fastest and most reliable, but also the most expensive and rare. They are mainly used for high-performance applications.
• MLC (Multi Level Cell): Each cell stores two bits of data. This makes them more affordable and common than SLC, but also slower and less durable. They are suitable for enterprise and consumer use.
• TLC (Triple Level Cell): Each cell stores three bits of data. This makes them even more affordable and common than MLC, but also slower and less durable. They are popular for consumer products and devices.
• QLC (Quad Level Cell): Each cell stores four bits of data. This makes them the cheapest and highest capacity, but also the slowest and least durable. They are good for read-heavy operations and data storage.
• PLC (Penta Level Cell): Each cell stores five bits of data. This makes them the newest and most experimental type, with potential for even higher capacity and lower cost, but also lower speed and durability. They are not yet widely available or tested.

Importance of SLC Cache:

SLC cache is a feature that some SSDs use to improve their performance and endurance. SLC stands for single-level cell, which means that each memory cell in the SSD can store only one bit of data. This makes the SSD faster and more reliable than other types of cells, such as MLC (multi-level cell) or TLC (triple-level cell), which can store two or three bits per cell, respectively.

However, SLC cells are also more expensive and have lower capacity than MLC or TLC cells. Therefore, most SSDs use MLC or TLC cells as their main storage, and reserve a portion of them as SLC cache. The SLC cache acts as a buffer that temporarily stores the data that is written to the SSD. When the SSD is idle, the data in the SLC cache is moved to the MLC or TLC cells in the background.

The advantage of using SLC cache is that it can speed up the write operations and reduce the wear and tear of the SSD. Writing data to SLC cells is faster and easier than writing to MLC or TLC cells, which require more voltage and time to program multiple bits per cell. Also, writing data to SLC cells causes less stress and degradation to the cells than writing to MLC or TLC cells, which have lower endurance and lifespan.

The disadvantage of using SLC cache is that it has limited space and can be filled up quickly if there are many write operations. When the SLC cache is full, the SSD has to write data directly to the MLC or TLC cells, which results in slower performance and higher wear. Therefore, the size and management of the SLC cache are important factors that affect the overall performance and endurance of the SSD.

There are two types of SLC cache: static and dynamic. Static SLC cache is a fixed amount of space that is always reserved as SLC cache, regardless of how much data is written to the SSD. Dynamic SLC cache is a variable amount of space that can change depending on how much data is written to the SSD. Dynamic SLC cache can use more space as SLC cache when there is less data on the SSD, and use less space as SLC cache when there is more data on the SSD.

Static SLC cache has the advantage of being consistent and predictable, but it also wastes some space that could be used as MLC or TLC storage. Dynamic SLC cache has the advantage of being flexible and efficient, but it also introduces more complexity and variability to the SSD performance.

SSD Type	Bits per Cell	Lifespan (P/E Cycles)	Use Cases
SLC	1	50,000-100,000	High-performance applications
MLC	2	10,000	Enterprise data center
TLC	3	3,000	Digital consumer products
QLC	4	2,000	Read-heavy operations, AI/ML, stream media/content delivery
PLC	5	n/a	Long-term storage, data archives

So what is "Best"?

There is no definitive answer to which type of SSD is the best, as it depends on your needs and preferences. Different types of SSDs have different trade-offs between capacity, speed, durability, and cost. Generally speaking, the more bits per cell, the higher the capacity and lower the cost, but also the lower the speed and durability.

To help you compare the different types of SSDs, I have created a table based on some sources from the web. The table shows the number of bits per cell, the expected lifespan in program/erase cycles, and some use cases for each type of SSD. Please note that these values are approximate and may vary depending on the manufacturer and model of the SSD.

Little table of comparison of brands and types, remember this is just suggestion not brand recomendation:

SSD type	Bus standard	Transfer protocol	Bandwidth	Transfer rates
WD Black SN850X NVMe PCIe M.2 2TB	PCIe 4.0 x4	NVMe 1.4	64 Gb/s	7000 MB/s read, 5100 MB/s write1
Samsung 980 Pro NVMe PCIe M.2 1TB	PCIe 4.0 x4	NVMe 1.3c	64 Gb/s	7000 MB/s read, 5000 MB/s write2
Samsung 970 Evo Plus NVMe PCIe M.2 1TB	PCIe 3.0 x4	NVMe 1.3	32 Gb/s	3500 MB/s read, 3300 MB/s write3
Crucial P1 3D NVMe PCIe M.2 1TB	PCIe 3.0 x4	NVMe 1.3	32 Gb/s	2000 MB/s read, 1700 MB/s write4
Samsung 860 Evo SATA III 2TB	SATA III (6 Gb/s)	AHCI	6 Gb/s	550 MB/s read, 520 MB/s write
Crucial MX500 SATA III 1TB	SATA III (6 Gb/s)	AHCI	6 Gb/s	560 MB/s read, 510 MB/s write

I personally use in my current PC three SSD Crucial P3 Plus 1TB M.2 2280 PCI-E x4 Gen4 NVMe, which i use for gaming, content creation and data transfers. I also house in pc case 3 Seagate Barracuda HDD 2TB ea for data storage, not to count few external HDD's for data storage. 

SSD topic is long as a river, but i hope i gave you a little roadmark how to look on ssd specs when buying one, not only looking at write and load speed, which is often just marketing thing. Have a good day :)