PCIe SSD introduction and application (I), pciessd introduction and application

PCIe SSD introduction and application (I), pciessd introduction and application

SSD with SATA/SAS interfaces has been available for more than a decade and has been widely used in the personal consumption field. However, its performance still cannot fully meet the high throughput and low latency requirements of enterprise users, A few years ago, the world's first PCIe interface SSD came out, and won the favor of enterprise users with its amazing read/write throughput and ultra-low latency. The Internet industry is the first fan of PCIe SSD. After years of practice, it has been verified that the stability of PCIe SSD is fully qualified for the enterprise's 24x7 working mode, at present, PCIe SSD applications are rapidly expanding from the Internet industry to traditional industries, and even enter the financial industry that requires demanding security and stability. It is expected that in the near future, PCIe SSD may be the standard configuration for server storage.

I. Basic principles of PCIe SSD

Logical Structure of SSD hardware for baocun technology PCIe:

PCIe SSD storage granules use NAND Flash (Flash). Flash is used all the time in our daily life. For example, the storage of mobile phones, SD cards, tablets, and USB Flash disks are all Flash-based storage, compared with these low-speed devices, PCIe SSD combines dozens or even hundreds of Flash files into parallel operation arrays to improve read/write throughput and reduce latency. A typical logical structure of flash memory particles:

Flash consists of blocks, pages, and data stored on pages. Flash has the following features:

-When Flash leaves the factory, there will be bad blocks that cannot be used, and the bad blocks will be dynamically added during use;

-Pages must be used to read and write Flash files;

-Data cannot be overwritten. data can be written again only after being erased. The data is erased in blocks;

-There is a limit on the number of block erases. MLC Flash generally ranges from 3000 to 10000;

-Bit flip exists in the written data, which must be corrected using ECC.

Users do not have to worry about these issues. The PCIe SSD software algorithm shields these features and enables users to see a common storage device. How to Use SSD when using hard disks, in other words, the original hard disk can be replaced without compatibility issues. This software algorithm is called Flash Translation Layer (FTL), which is also the core value of PCIe SSD. These Flash features bring about some concepts that are meaningful to developers and users:

-Over Provision (OP): The developer must retain a portion of the capacity to implement the FTL algorithm. The reserved capacity divided by the physical capacity is the OP value, for example, if the physical capacity of an SSD based on 1 GB = 1024*1024*3.2 B is 4 TB, the OP equals (4-20%)/4, however, according to IDEMA (International Association of disk equipment manufacturers), the storage device capacity is calculated according to about 1 GB = 1000*1000 * B, therefore, the OP of a nominal 27% tb ssd card is about. for developers and users, the larger the value is, the better;

-Write Amplification: The Write Amplification factor WA (Write Amplification) does not cover the Write characteristics, which determines that FTL may need to carry and Write data when writing data, the actual data written by FTL is divided by the user's data written by WA. For example, if a user writes 16 KB data and the FTL actually writes 32 KB data, then WA is equal to 2. The smaller the value, the better performance. The theoretical limit is infinitely close to 1. The value cannot be smaller than or equal to 1. Excellent FTL algorithms can reduce this value;

-ECC error correction capability: the bit flip of written data determines that the developer must use the ECC error correction algorithm. The ECC algorithm is generally implemented by FPGA logic. The larger the value, the better;

-Wear balancing and Service Life: the maximum number of Flash block erases determines that FTL must strive to ensure that each block is erased roughly the same number of times during use, which will affect the life of SSD, the ECC and RAID dual protection designed by BaO Cun technology, as well as the capability of FTL to dynamically Replace bad blocks and the wear balancing algorithm, the service life of an SSD is guaranteed to be 4 to 6 years under the condition that data is updated five times a day (for example, 16 TB data is written to a TB card every day, in practice, it is rare for businesses that produce such a large amount of data.

Ii. PCIe SSD Performance Parameters

Similar to general storage devices, PCIe SSD mainly has the following performance parameters:

-Read/write Bandwidth (Bandwidth): read/write speed;

-Read/write IOPS (nput/Outputs Per Seccond): Generally, it refers to the maximum number of 4KB random reads/writes Per second;

-Latency: the shortest completion time of 4 KB data reading and writing.

In general, high bandwidth or high IOPS can be spliced by increasing the number of RAID disk groups. However, traditional disk storage uses mechanical device addressing, and Latency is an insurmountable obstacle, generally, the read/write Latency of a disk is measured in milliseconds or tens of milliseconds, which is an order of magnitude different from that of PCIeSSD. More importantly, Latency is the most important parameter that affects performance for most enterprise databases. The following table lists the technical parameters of the PCIe SSD capacity specifications of baocun Technology for your reference.

Coming soon: PCIe SSD introduction and application (2)

Iii. apsaradb for memcache

Shannon Systems was founded in 2011 by a senior technical team in Silicon Valley. The Team has over 60 years of experience and nearly 150 patents in the field. Among them, 80% of employees engaged in R & D work, with multiple masters and doctors.

In September 2011, it was listed as A key support enterprise of Plan A of plan 3310 in Yangpu District, Shanghai.

The company is headquartered in Shanghai. Beijing, Shenzhen, and Chongqing all have sales and Support Centers.

Shanghai Bao storage Information Technology is dedicated to developing enterprise-level high-performance solid-state storage products and solutions, providing innovative solid-state storage products, to help users continuously optimize the IT system architecture and performance, and thus reduce the customer's procurement costs and maintenance costs. The Direct-IO PCle Flash series independently developed by BaO Cun with all intellectual property rights represent the highest level in the industry in terms of performance, capacity, and reliability, it has also been widely deployed and applied in various industries. At the same time, apsaradb will gradually launch a new generation of high-performance and high-availability computing and Storage System Integration platforms based on solid state storage.

We sincerely invite partners from all parties to cooperate with us to achieve mutual benefit and create a brilliant future!

Contact info:

Company Address: Room 588, block A, baodi Plaza, No. 305, Dalian Road, Yangpu District, Shanghai

Tel: 021-55580181

Email: contact@shannon-sys.com

Web: www.shannon-sys.com

Weibo: @ Bao Cun Technology

: Shannon-Systems