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Which SSD technology is faster?



  The NVM Express logo. NVM Express, Inc.

NVMe disks are currently a large part of the computer storage, and not without reason. Not only does an NVMe solid-state drive (SSD) leave most older SSDs in the dust, it is also super-fast compared to standard 3.5- and 2.5-inch disks.

NVMe versus SATA III

Take, for example, the 1

TB Samsung 860 Pro, a 2.5-inch SSD with a maximum sequential reading speed of 560 megabytes per second (MB / s). Its successor, the NVMe-based 960 Pro, is more than six times faster than that, with a top speed of 3,500 MB / s.

This is because the pre-NVMe disks connect to a PC via SATA III, the third revision of the serial ATA computer bus interface. NVMe has since become the host controller interface for newer, more advanced SSD & # 39; s.

SATA III and NVMe are the terms most commonly used to distinguish between old-school drives and the new hotness that everyone wants. However, NVMe is not the same type of technology as SATA III.

We will discuss the reason why we use the terms "SATA III" and "NVMe" to later compare the technologies.

What is SATA III?

  SATA III cables
Rosewill

In 2000, SATA was introduced to replace the preceding Parallel ATA standard. SATA offered connections at higher speeds, which meant significantly improved performance compared to its predecessor. SATA III was rolled out eight years later with a maximum transfer speed of 600 MB / sec.

SATA III components use a specific type of connector to plug into a laptop and a specific type of cable to connect to a desktop PC motherboard.

As soon as a disk is connected to the computer system via SATA III, the work is only half done. In order for the disk to actually talk to the system, it needs a host controller interface. That task is from AHCI, which is the most common way for SATA III drives to talk to a computer system.

For many years, SATA III and AHCI have performed admirably, also during the early days of SSD & # 39; s. However, AHCI was optimized for high-latency rotating media, not for low-latency, non-volatile storage such as SSD's, a representative of disk manufacturer Kingston explained.

Solid-state disks became so fast that they eventually saturated the SATA III connection. SATA III and AHCI simply could not offer enough bandwidth for increasingly capable SSDS.

As disk speeds and capabilities increased, a better alternative was sought. And luckily it was already in use on PC & # 39; s.

What is PCIe?

PCIe is another hardware interface. It is best known as the way a graphics card fits into a desktop PC, but it is also used for sound cards, Thunderbolt expansion cards and M.2 drives (more on that later).

<img class = "wp-image-322276 size-full" data-page speed-lazy-src = "https://www.howtogeek.com/wp-content/uploads/2017/08/ximg_5994a79d22399.jpg. pagespeed.gp + jp + jw + pj + ws + js + rj + rp + rw + ri + cp + md.ic.g_ByszHAq2.jpg "alt =" A gigabyte motherboard with PCIe slots [19659021] Gigabyte

If you look at a motherboard (see above), you can easily see where the PCIe slots are, they usually come in x16, x8, x4 and x1 variants, which indicate how many lanes for data transfer a slot has. The higher the number of lanes, the more data you can move at the same time, so graphics cards use x16 slots.

There is also an M.2 slot in the image above, directly below the top x16 slot. 2 slots can use up to four lanes, so they are x4.

The main PCIe slots in each computer have lanes connected to the CPU for the best possible performance, the rest of the PCIe slots connect to me t the chipset. This also supports a reasonably fast connection to the CPU, but not as fast as the direct connections.

Two generations of PCIe are currently in use: 3.0 (the most common) and 4.0. From mid-2019, PCIe 4.0 was brand new and only supported on AMD & # 39; s Ryzen 3000 processors and X570 motherboards. Version 4 is, as you would expect, faster.

However, most components do not yet saturate the maximum bandwidth of PCIe 3.0. Although PCIe 4.0 is impressive, it is not yet a necessity for modern computers.

RELATED: PCIe 4.0: What is new and why it is important

NVMe About PCIe

PCIe is then like SATA III; they are both used to connect individual components to a computer system. Just as SATA III needs AHCI before a hard drive or SSD can communicate with a computer system, PCIe-based drives rely on a host controller, called non-volatile memory express (NVMe).

But why don't we talk about SATA III versus PCIe drives, or AHCI versus NVMe?

The reason is fairly simple. We have always mentioned drives as SATA-based, such as SATA, SATA II and SATA III – no surprise there.

When disk manufacturers started making PCIe disks, there was a short period of time when we talked about PCIe SSD & # 39; s

However, the industry had no standards to work around like with SATA disks. Instead, as Western Digital explained, companies used AHCI and built their own drivers & firmware to run those disks.

That was a mess and AHCI was still not good enough. As Kingston explained to us, it was also harder for people to use disks that were faster than SATA because they had to install special drivers instead of a plug-and-play experience.

Eventually the industry started the standard that became NVMe and replaced AHCI. The new standard was so much better, it made sense to talk about NVMe. And the rest, as they say, is history.

NVMe was built with modern, PCIe-based SSDs in mind. NVMe drives can accept many more commands at the same time than SATA III mechanical hard drives or SSDs. That, combined with a lower latency, makes NVMe drives faster and more responsive.

What do NVMe disks look like?

  A Samsung M.2 SSD
Samsung

If you are going to shop for an NVMe-based drive today, what you want is an M.2 chewing gumstick. M.2 describes the form factor of the disc or, for our purposes, how it looks. M.2 drives usually have up to about 1 TB of storage, but they are small enough to hold between your thumb and forefinger.

M.2 drives can be connected to dedicated M.2 PCIe slots that support up to four rows of data transfer. These drives are usually based on NVMe, but you can also find M.2 drives that use SATA III – read the package carefully.

SATA III-based MATAs are not that common nowadays, but they do exist. Some popular examples are the WD Blue 3D NAND and the Samsung 860 Evo.

RELATED: What is the M.2 expansion slot and how can I use it? [19659009] Do you have to dump SATA III drives?

Although NVMe is fantastic, there is no reason to give up SATA III drives. Despite the limitations of SATA III, it is still a good choice for secondary storage.

For example, anyone who builds a new PC would do well to use an M.2 NVMe drive for his boot drive and primary storage. He could then add a cheaper hard drive or 2.5-inch SSD with larger capacity as secondary storage.

It could be a good idea to run all your storage on PCIe. However, NVMe drives are currently limited to approximately 2 TB. Higher capacities are also priceless. A budget 1 TB, M.2 NVMe drive usually costs around $ 100 (which is approximately what a high-performance 2 TB SATA III hard drive costs).

Prices can of course change if we get an even higher capacity M. 2 discs. Kingston said we can expect M.2 drives with a capacity of 4 and 8 TB around the beginning of 2021.

Until then, the combination of M.2 with secondary SSD & hard drives is the best option.

The same idea applies to laptops. If you buy a new rig, look for one with NVMe flash storage and a spare 2.5-inch bay for a SATA III hard drive or SSD.

However, not all NVMe drives are made equal. It is certainly worthwhile to read reviews on your target drive before purchasing one.


If you have a fairly new desktop PC or laptop, chances are that it has M.2 slots that support NVMe. It is worth upgrading your PC!


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