What is nvme hard drive?

nvme is a solid state drive; it is a specification for solid state drives using PCI-E channels. The purpose of the nvme specification is to make full use of the low latency and parallelism of the PCI-E channel, as well as the parallelism of contemporary processors, platforms and applications, to greatly improve the read and write performance of solid-state drives at controllable storage costs. Reduce the high latency caused by the AHCI interface and completely unleash the ultimate performance of solid-state drives in the SATA era.

The operating environment of this tutorial: Windows 7 system, Dell G3 computer.

NVMe is actually a logical device interface standard like AHCI. NVMe is a specification for solid-state drives that use PCI-E channels. At the beginning of the design, NVMe took full advantage of the low latency and parallelism of PCI-E. sex. Its most obvious advantage over traditional solid-state drives using SATA channels is its ultra-high read and write speeds.

NVMe is the abbreviation of Non-Volatile Memory express (Non-Volatile Memory Host Controller Interface Specification). It is a protocol that enables solid-state drives (SSD) to run faster. It is now used by enterprise users has become increasingly popular.

The easiest way to understand what NVMe is is to use an analogy - suppose you just bought a sports car that can reach a speed of 400 kilometers per hour, which is 3 to 4 times that of your previous old car. . The only problem is that ordinary roads cannot allow driving at such a speed, and the speed limit on urban roads is usually dozens of kilometers per hour, and traffic flow issues often have to be considered. If you want your sports car to go faster, you need to drive it another way.

This scenario is a bit like the situation in the storage industry after manufacturers launched SSDs based on flash memory technology. Flash technology is many times faster than traditional mechanical hard drives (how many times faster depends on the device you use), but early devices all used the same SATA or SAS connections as hard drives to connect to systems and networks. While these interfaces are adequate for the performance a hard disk drive (HDD) can provide, they create bottlenecks for SSDs. This is especially a problem for enterprise big data analytics and other data-intensive workloads.

These performance issues have prompted people to look for better ways to connect SSDs to servers, which is where NVMe comes in.

1. What is NVMe?

The NVMe protocol standard is overseen by NVM Express, a group of more than 100 organizations A consortium of organizations working to develop faster protocols to improve the performance of non-volatile storage. The organization is led by a 13-company board of directors, including Cavium, Cisco, Dell EMC, Facebook, Intel, Micron, Microsemi, Microsoft, NetApp, Samsung, Seagate, Toshiba Memory and Western Digital.

The highest theoretical speed that HDD can achieve, compared with the highest theoretical speed provided by SATA and NVMe

The official definition of NVMe describes it as "an open A collection of standards and information to fully unlock the benefits that non-volatile storage can provide in all types of computing environments, from mobile to data centers. NVMe is designed from the ground up to provide high bandwidth and performance for current and future NVM technologies. Low-latency storage access."

NVMe is an interface specification for connecting storage to servers through the PCI Express bus. Simply put, it allows SSDs to communicate with the host system faster. It helps alleviate bottlenecks that occur when flash memory is connected to the system via SAS or SATA, which were originally designed for HDDs.

2. NVMe is much faster than SATA or SAS

NVMe controllers improve performance in several different ways. One is to use the PCIe bus, which connects storage directly to the system CPU. This direct connection eliminates some of the necessary steps for SATA and improves overall performance.

In addition, NVMe SSD achieves parallelism to a large extent, greatly improving throughput. When data is transferred from storage to the server host, it enters a row or queue. Traditional SATA connections can only support one queue and can only receive 32 pieces of data at a time. Going back to the car analogy, it's like having only one lane of traffic for 32 cars.

NVMe storage supports up to 64,000 queues, each with 64,000 entries. In other words, it's like going from a one-way street to a road with 64,000 lanes, each of which can accommodate 64,000 cars, which has a huge impact on overall performance.

Just like our analogy said that urban roads generally have speed limits of tens of kilometers per hour, SATA and SAS connections also have speed limits. For SATA, the theoretical maximum transfer speed is 6.0 Gbps (in practice, the maximum transfer speed is much lower). This is equivalent to setting an upper limit on the operating speed of SATA SSD. Beyond a certain limit, using faster flash memory has no impact on the overall performance of the system because the SATA connection will create a bottleneck.

For most consumers, SATA SSDs provide enough performance to get through daily tasks. And because SATA SSDs are cheaper than NVMe SSDs, most consumer-grade solid-state storage still uses the SATA interface.

However, businesses typically handle much more data than consumers, and for them, the latency introduced by a SATA connection can become an issue.

The Intel 750 series is one of the solid state drive products that supports NVMe technology

3. Only SSD runs on NVMe

Because NVMe The drive is much faster than SATA, so using NVMe alongside an HDD to improve performance seems like a good idea. But keep in mind that NVMe stands for Non-Volatile Storage Interface Specification, and it's designed specifically for non-volatile storage like NAND flash (although it can also be used with newer non-volatile memories like 3D XPoint).

When the system reads data from the HDD, it can only read one piece of data at a time. Because it has to rotate to get to the correct physical location for the first block, then rotate again to move to the correct location for the second block, and so on. Flash memory and other non-volatile storage technologies, on the other hand, have no moving parts. This means the system can read data from many different locations simultaneously. This is why SSDs can take advantage of the parallelism provided by NVMe, but HDDs cannot.

4. PCIe and NVMe are related, but they are not the same thing

For many people, the most confusing part of NVMe is its relationship with PCIe. Some vendors use the NVMe label to refer to their SSDs, others use the PCIe label, and still others seem to use the terms interchangeably.

While PCIe and NVMe are closely related, the two terms refer to slightly different technologies. Think of PCIe as the physical part of the system. When you plug an NVMe SSD into a server, you need to connect it through a PCIe slot.

In contrast, NVMe is a protocol, a set of software and hardware standards that allow SSDs to use the PCIe bus. Suffice to say, NVMe is the language that allows storage devices to connect to servers, while PCIe is the actual physical connection.

5. NVMe-oF connects SSD to the network

This article mainly focuses on standard NVMe, which connects SSD directly to the server, but the NVM Express organization also released NVMe over Fabric (NVMe - oF) specification that connects non-volatile storage for block storage to the network. According to the organization, "NVMe-ofF defines a common architecture that supports a range of storage network fabrics for the NVMe block storage protocol on top of the storage network fabric." This includes enabling front-end interfaces in the storage system, extending Large numbers of NVMe devices and extending the reach of NVMe devices and NVMe subsystems within the data center.

The NVMe-oF specification is approximately 90% identical to the NVMe specification; however, it does use a different transport mapping mechanism. NVME-oF also comes in two different variants: one for RDMA and one for Fiber Channel.

The NVMe-oF specification is also much newer than the NVMe specification. Although some manufacturers have announced support for this technology, few manufacturers actually sell NVMe products. Expect this technology to become more common in the coming years.

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