Shulou(Shulou.com)06/02 Report--

The performance of flash memory can be said to be worthy of its name, but its speed can still be improved, especially in the data center field.

In pursuit of faster storage performance, enterprises are more and more interested in NVMe. This is a "flash-friendly" technology that can greatly improve the read and write performance of solid state hard drives (SSD). So, what does it mean for SATA?

Let's take a look at what professionals need to know about the "love-hate entanglement" between NVMe and SATA.

What is NVMe?

NVME is a host controller interface specification that uses the PCI Express (PCIe) bus to connect the SSD to the server. The technology was developed by NVM Express. NVM Express is a non-profit industry association supported by leading IT companies and storage vendors such as Cisco, Dell, NetApp, Seagate, and Western Digital (Western Digital).

NVM Express explained:

"the interface provides optimized command issues and completion paths. It supports parallel operations by supporting up to 64K commands in a single Iripple O queue to the device. In addition, support for many enterprise features has been added, such as end-to-end data protection (compatible with T10 DIF [data integrity fields] and DIX [data integrity extension] standards), enhanced error reporting and virtualization."

NVMe solves a problem that occurs when flash-based storage conflicts with legacy data transfer technologies: bottlenecks.

In essence, the storage interface and bus structure designed for disk has been unable to keep up with the pace of SSD. When using a server with powerful multicore processors and a large number of RAM, it is obviously not a wise choice to waste a lot of time waiting for data transfer.

NVMe saves the world. Compared with SATA, it can load data with extremely fast speed and lower latency, provide fast performance, and enable enterprises to run smoothly storage workloads that may come to a standstill at any time.

In terms of performance, NVMe is a rule changer, but it cannot guarantee faster flash performance. Before taking action, storage managers will want to finish their work and improve the technology to ensure that it fits their IT goals. They may find that other factors are bottleneck effects and performance effects.

NVMe SSD is available from many suppliers, including Intel, Micron, Samsung and Western Digital. Installation options include the M.2 and 2.5-inch U.2 and, of course, the PCI card.

What is SATA?

SATA (Serial Advanced Technology Attachment, Serial Advanced Technology Accessories) is the successor to the PATA bus interface used to connect ssd, hard disk drives (HDD) and optical drives. Anyone familiar with computers will remember that the wiring of the SATA interface is easier to operate than the PATA.

But there is much more to SATA's story than cleaner and easier to manage cabling.

Since the advent of SATA in 2000, the standard has experienced several performance improvements. For example, SATA I or 1. 0 can transfer data at speeds up to 15mb / s. To SATA III, the speed can reach 600 MB/s.

There is also revision 3.2, launched in 2013, which supports both SATA and PCIe in the SATA Express connector specification (not to be confused with eSATA) with a design speed of 1969 MB/s. Although impressive on paper, the industry largely skipped SATA Express.

SATA also supports hot-swappable, which means that SATA storage devices can be plugged in or removed from the system, and the system can still function normally after being powered on, which is a feature that its predecessor PATA did not have. It also uses the Advanced Host Controller Interface (AHCI) interface, which allows the use of native command queues (NCQ), a performance-enhancing drive optimization technique that provides the hot-swappable functionality mentioned earlier.

The standard is maintained by SATA- IO, a non-profit organization founded in 2004, with supporters including AMD, Dell, Hewlett-Packard, Intel, Micron, Seagate and many other large IT companies.

What's the difference between NVMe and SATA?

Behind these acronyms, there are significant differences to reshape the enterprise data storage environment.

NVMe: only flash memory needs to be used

Traditional HDD is not among them. Mechanical disks are too slow for flash optimization interfaces. However, SATA can be applied to both SSD and HDD.

Performance problem

SATA SSD may have better storage performance than its HDD counterparts, but NVMe SSD can significantly outperform them.

SATA III operates at a theoretical speed of 600 MB/s, but the SSD connected to this interface usually does not achieve that level of data throughput. A 7200 RPM SATA HDD can only reach a fraction of the speed of SDD, providing the speed of 100MB/s.

Recently, Samsung released a consumer-grade NVMe SSD, Samsung 970 PRO NVMe and 970 EVO NVMe. In the test, the read speed of both reached 3500 MB/s. When writing data to SSD, 970 PRO exceeds 970 EVO at speeds of 2700 MB/s and 2500 MB/s, respectively.

Favorable parallelism

Another feature of defining NVMe is its parallelism. As mentioned at the beginning of this article, NVMe has a queue depth, or command capacity of 64K per queue, or even supports 64K queues. SATA processes only one command queue with a queue depth of 32.

By enabling a large number of IO (input / output) operations in parallel on the channels of the PCIe bus, this approach can be well used for multicore processing, reducing bottlenecks, and keeping data fast in and out of modern CPU. It is consistent with the qualification of flash random access operation, which leads to the rapid improvement of the overall performance.

SATA is durable and economical.

SATA is well established and doesn't seem to disappear any time soon.

Over time, both SSD and HDD manufacturers continue to support standards for high-capacity drives. They are also usually cheaper than NVMe.

In the end, NVMe may go a little too far. In addition to business-critical applications and transaction-intensive databases, it may be difficult for users to justify the cost of NVMe for applications that do not want to take advantage of the high-performance capabilities of the technology.

Will NVMe and SATA be parity?

Although the price of NVMe continues to fall, SATA SSD is usually lower.

Take the previous Samsung 970 PRO NVMe as an example. The consumer SSD version of the 512 GB retails for $249.99, while the critically acclaimed Samsung 860 Pro 2.5in SATA SSD retails for $214.99. If users' systems can't make full use of Samsung's NVMe SSD, it's best to save money with SATA SSD.

As IT buyers know, rising to the enterprise level of SSD is another competitive environment, and the price problem may be more obvious. Often, their true costs are masked by the fact that they are included as part of the system configuration. In any case, companies should consider whether to pay thousands of dollars for a multi-TB NVMe drive, or to use SATA SSD to pay less for the same capacity, and of course performance will be worse.

Still, the price of NVMe is still falling, which bodes well for companies looking to improve their business capabilities through storage.

NVMe or SATA?

It is clear that technologies that take advantage of fast business with enterprise storage workloads will find supporters among today's data center operators. Enterprises looking for faster and more responsive application and database performance will continue to focus on the market for systems that support NVMe.

But don't take the SATA out.

For the foreseeable future, NVMe is expected to coexist with SATA and SAS (Serial attached SCSI) devices and in a data center environment. In order to implement a tiered storage policy, where the cost and performance characteristics of the storage device are consistent with the values of the data placed on it.

Looking ahead, there are other signs that storage vendors are looking to further widen the performance gap between NVMe and SATA. Intel is a good example. Although the company sells NVMe SSD, which is based on flash memory, it also brings NVMe solid-state hard drives to market.

Aoteng is based on the company's 3D XPoint technology, a persistent memory or storage-like memory (SCM) solution that combines the performance characteristics of dynamic random access memory (DRAM) with the ability to save data in the event of a flash power outage.

Then there is the NVMe over Fabrics (NVMeoF) protocol, which allows ultra-low latency storage services to be provided from NVMe SSD outside the server over Ethernet, fibre Channel, and InfiniBand networks, blurring the line between internal and external storage. Obviously, in the next few years, the NVMe market will develop faster than ever before.

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