I believe you are familiar with nvme, SATA and m.2. Today, let’s share my personal cognition of these contents, that is, the relevant knowledge of the current m.2 SSD hard disk.
1、 What is m.2?
First, m.2 is an interface, which appears in the slots on notebooks and desktops. M. 2 interface mainly replaces msata interface. Msata looks like this:
It appeared in the notebook a few years ago. As the main hard disk of the notebook, it is a little small and does not occupy space. It can make the notebook light and thin. It was originally promoted by Intel for ultrabook.
The shape is the same as the full height wireless network card, but the interfaces used are different, so it can not be mixed. However, msata only supports sata3 The theoretical transmission speed of 6GB / s of 0 protocol makes it unable to be applied to more scenarios and keep up with the performance development of SSD. At present, because of its compact characteristics, it is applied in the scene of solid-state mobile hard disk.
Followed by the m.2 interface specification mainly promoted by Intel. Compared with msata, m.2 interface has more advantages in transmission belt, capacity, lightness and so on. Therefore, it is gradually used in a small space such as notebook to be used in desktop.
Secondly, there are three sizes of m.2 SSD: 42mm 22mm, 60mm 22mm and 80mm 22mm. In fact, it is the corresponding meaning of the number 224222602280 on the hard disk we usually see. Different lengths can accommodate different numbers of flash memory particles, so different capacity limits can be reached. At present, our common size is 2280. However, many peripheral products, such as hard disk boxes, will support three sizes.
Thirdly, there are two types of m.2 interfaces: socket2 (B key - ngff protocol) and socket3 (M key - nvme protocol). Socket2 supports SATA and PCI-E 2 interfaces, with a maximum rate of 700MB / s and a write rate of 550mb / s. Socket3 can support PCI-E 4 interface, and the theoretical bandwidth can reach 4GB / s. In the figure above, both the left 1 and the left 2 support nvme protocol, while the right one only supports SATA protocol. Therefore, when purchasing or updating m.2 SSD, you need to pay special attention to the interface type, support protocol and support motherboard.
Therefore, m.2 is an interface type, which is the same level concept as SATA and IDE. IDE interface is basically invisible. SATA is the mainstream, and m.2 has been popularized slowly, and the speed is quite fast.
2、 What protocols does m.2 SSD support?
I believe even if you don’t understand, you’ve heard that m.2 SSD supports SATA bus and PCI-E bus. At this level, both SATA and PCI-E are buses (channel standards), which are not the same concept as the physical interface on the motherboard.
If sata3 is mentioned 0, you may have a speaker. The transmission rate limit of this bus is 6GB / s, that is, the maximum transmission speed can reach 600m / s. Therefore, at present, when purchasing 2.5in SSD, the speed of publicity page is 550m / s. After all, transmission is a loss, which cannot meet the theoretical standard, but take sata3 The SSD of 0 bus has been developed to the limit, that is, the transmission speed of 550m / S is sata3 0 limit. Basically, all businesses’ 2.5in SSDs can reach the transmission speed of 550m / s.
Therefore, even if the SSD with m.2 interface uses SATA channel, no matter how you measure the speed, the speed cannot exceed 6gbps. In other words, if the speed tested is lower than 6gbps, it should be the SATA channel.
Another concept corresponding to SATA channel is PCI-E, which is also a channel concept. Its full name is PCI expss. At present, the mainstream should be PCI expss gen3 x 4 channel. Gen3 is the algebra of PCI expss, which is similar to usb1 of USB protocol 0，USB2. 0，USB3. 0 The rear x 4 is the size of the slot on the motherboard.
At present, the mainstream m.2 SSDs are PCI expss gen3 0 x 4 channels. If the SSD is replaced by a notebook, it is also necessary to find out the channel version supported by the m.2 slot of the notebook motherboard. For example, I didn’t know before. An Aigo P2000 1T m.2 SSD was added to Xiaomi notebook 15 Pro 2019, but the nominal speed could not be reached through any measurement. So I went to Xiaomi’s customer service for consultation and confirmation. Only then did I know that this notebook only supports PCI expss Gen2 0, so it can only reach the speed under this channel standard.
Different sizes correspond to different gold finger lengths. For example, the graphics card is connected to PCI expe x 16 to provide more efficient data transmission. For example, the brand desktop computer I use provides m.2 slot, but it can’t recognize nvme, but there is PCI expss x 1 socket on the motherboard, and the idle m.2 SSD can only come second. I bought a Jiayi adapter to reduce the speed of Aigo P2000 512 to 800MB / s.
https://item.jd.com/100023635668.html
Jeyi nvme adapter card PCIe to m.2 adapter card full speed m.2 gen3 full speed expansion card SK1
So the question is, what the hell is nvme.
3、 “M.2 drive”
Casually search the SSD. At present, the mainstream m.2 SSD will follow nvme. What is this?
Nvme, namely NVM expss, is a logical device interface specification, which is the same level concept as AHCI. It is with ah