Overview of the 46 week card and storage market in 2019

With the development of technology, people have more and more requirements on the I/O performance of storage devices. At present, solid-state drives (SSDS) based on flash arrays have faster reading and writing speed than traditional hard drives (HDDS). However, in some scenarios, the parallel channel potential inside SSDS cannot be fully released, leading to the bottleneck of storage performance.

Data in the western conference's latest patent (patent name: QUALITY OF SERVICE AWARE STORAGE CLASS/NAND FLASH MEMORY HYBRID SOLID STATE DRIVE the patent number: US 10430329 B2) revealed a NAND FLASH MEMORY and other such as STORAGE CLASS MEMORY STORAGE media (SCM) together, set each configuration OF HYBRID SSD to realize high bandwidth and low latency STORAGE solution.

In 2007 samsung launched the world's first hybrid drive MH80, combined with the HDD, low cost and high capacity SSD performance, Seagate, western digital and armoured spiderman (original Toshiba storage) launched a similar product, as the main storage to HDD, collocation of NAND flash memory cache, and the two parts have their own master control chip, the common data stored in NAND flash, not common data stored in HDD, through the driver to read and write data to accelerate the deployment.

Although hybrid hard drives are not new to the market, they have little effect on write response due to their more read-write function, and the SSD part is only used as a cache, which does not improve the read-write drive of HDD part, so they are not widely used.

Moreover, with the NAND flash memory technology in recent years has successfully switch from 2 d to 3 d and 96 TLC product mass production, QLC also speed up the popularization, and since the second half of 2018, storage market downturn of the market, NAND flash memory unit bit costs are falling, so I'm afraid by the method of SSD and HDD has been unable to meet the market demand. Storage vendors need to constantly develop more leapfrog technology to drive product innovation.

In 2015, Intel took the lead in successfully developing a 3D xpoint-based storage level memory (SCM), whose theoretical speed can reach 1000 times of NAND flash memory, and applied it to aoteng series products. In 2019, it launched the hybrid solid-state disk 'aoteng H10' integrating aoteng memory and NAND flash memory. Data that requires a low latency transfer rate is stored in the SCM, and data that does not require a low latency is stored in the NAND flash media.

In addition to Intel, samsung also actively promoted the popularity of SCM and launched z-ssd, which is currently mainly targeted at the data center market. SCM is a non-volatile memory technology that is far better than NAND flash in theoretical performance, and its price is also between DRAM and NAND flash. Therefore, it is undoubtedly preferable to match NAND flash with high-capacity SSD with higher performance requirements.

In the new hybrid SSD solution, the importance of master control is highlighted

The insurmountable problem in hybrid SSD storage solutions is how to tell which data needs low-latency processing and which doesn't, and how to 'direct' the data to the right storage medium, which requires the SSD's 'brain' master chip to run a series of command programs smoothly.

As described in the read and write command execution model disclosed in the western data patent, when the host receives the write command, it first needs to distinguish whether there is a low latency transmission demand for the data, if there is, it is stored in the SCM medium, and if not, it is stored in NAND flash.

After received from the host read commands, execute the command, guarantee for subsequent function and the need to perform a 'query process', confirm the next order is whether there is a low latency requirements, if there is no command to terminate, if any, need to confirm whether still have the remaining space in SCM, if there is space left, will be data to SCM to be obtained from the NAND flash memory, if not, you need to perform alternative algorithm will backup data out to the NAND flash memory.

The sequence of algorithms used in the write/read command above is done on the master chip. In fact, with the introduction of NAND flash into the 3D stack and TLC/QLC era, the role of master chips has become increasingly important. For example, in the QLC era, with the increasing number of bits per cell, the error probability is also increasing, and the efficient error correction scheme in the main control chip can also extend the service life of NAND flash memory, which is of great significance.

From heterogeneous storage in data center to hybrid SSD, set the length of each storage medium to meet the needs of users

In the data center market, heterogeneous storage has been basically become the consensus of the original factory, since the Intel proud by teng series products take the lead in layout, between the DRAM and SSD new level 3, including a proud proud teng DC lasting memory, teng solid-state disk (3 d) XPoint and QLC 3 d NAND flash disk, each layer of the velocity difference was only about 10 times, make the storage structure more fluent.

Samsung and kaisei (formerly Toshiba memory TMC) have also released z-nand xl-flash for the data center market, and their products are also location-based storage level memory (SCM) to address the performance gap between memory and FLASH. Meguiar's also actively promotes the advantages of QLC technology in read-intensive applications, reducing performance differences between DRAM and SSD.

Western data and SK hynix recommend de-clustering partition storage, through the software design to achieve smr-hdd, zns-ssd and other different storage media in the same architecture operation.

At present, NAND flash is still used as the single main storage medium in SSD system. Adding SCM storage medium with higher performance to NAND flash can not only improve the overall SSD performance, but also offset the high cost of SCM. Therefore, it can be regarded as an economical and efficient option in the future mass data storage demand.


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