New type of SSD-storage will reduce power consumption in the data center - how it works

The system will reduce electricity costs by half.

/ photo Andy Melton CC BY-SA

Why do we need a new architecture

According to estimates by Data Center Dynamics , by 2030, electronic devices will consume 40% of the total energy generated on the planet. Approximately 20% of this amount will be in the IT sector and data centers. According to European analysts, the data center already "take" 1.4% of all electricity. This figure is expected to rise to 5% by 2020 .

A significant portion of the electricity consumed SSD-storage. In the period from 2012 to 2017, the share of solid-state drives in data centers increased from 8 to 22% . Although SSDs consume a third less power ( PDF, p. 13 ) than HDDs, on the scale of data centers, electricity bills remain large.

To reduce the power consumption of solid-state drives in the data center, MIT engineers have developed a new SSD storage architecture. It is called LightStore and allows you to connect drives directly to the network of data centers, bypassing the storage servers. According to the authors, the system will reduce energy costs by half.
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How it works

LightStore is a key-value flash storage in which user requests to drives are displayed as keys. They are then sent to the server, which provides the data associated with this key.

The system contains an integrated energy efficient processor, DRAM and NAND memory. It is controlled by a controller and special software. The controller is responsible for working with NAND arrays, and the software is responsible for processing KV requests and storing key pairs. The software architecture is built on the basis of LSM-tree , which is used in many modern DBMS.

The architecture diagram can be represented as follows:

The diagram shows the basic components of LightStore. A cluster of nodes works with key-value pairs. Application servers connect to the system using adapters. They convert client requests (for example, fread () from the POSIX API) into KV requests. The architecture also has separate adapters for YCSB , block (based on the BUSE module) and file storages.

By distributing requests, the adapter uses consistent hashing . It is used in systems like Redis or Swift. Using the KV request key, the adapter generates a hash key, the value of which determines the target node.

The capacity of the LightStore cluster scales linearly - just add additional nodes to the network. In some cases, you may need to purchase new switches. However, the developers have provided each node with additional slots for connecting NAND-chips.

Architectural potential

MIT engineers say the bandwidth capacity of the LightStore solution is 620 Mbps for 10 Gigabit Ethernet. One node consumes 10 watts instead of the usual 20 watts (in SSD systems used by data centers today). In addition, the equipment takes half the space.

Now developers are refining some points. For example, LightStore does not know how to work with queries on a range and small queries. These features will add in the future, as LightStore uses LSM-trees. Also, the system still has a limited set of adapters - YCSB-and block adapters are supported. In the future, LightStore will be able to handle SQL queries, etc.

Other developments

In the summer of 2018, Marvell, the company developing the storage system, introduced a new line of SSD controllers based on AI systems. The developers have implemented NVIDIA deep learning accelerators in standard controllers for data centers and client applications. As a result, they have created an autonomous architecture that consumes less power compared to classic SSD controllers. The company hopes that the system will find application in peripheral computing, big data analytics and IoT.

Recently updated line of drives Western Digital Blue. In April, the developers presented a solution - WD Blue SSD based on SanDisk technology, which WD purchased a year ago. The updated WD Blue SSD features enhanced performance and energy efficiency. The architecture is built on the basis of the NVMe specification, which allows access to SSD connected via PCI Express.

This specification improves the performance of SSDs with a large number of simultaneous requests and speeds up access to data. Additionally, NVMe allows you to standardize the SSD interface - hardware manufacturers no longer have to spend resources on developing unique drivers, connectors and form factors.

Perspectives

The SSD market for data centers is moving towards simplifying the architecture, automating the operation of storage components and increasing energy efficiency. The development of engineers from MIT solves the last problem. The authors expect that LightStore will become the industry standard for SSD storage in the data center. And we can assume that in the future, new, even more efficient architectures will appear on its basis.

Several materials from the First Corporate IaaS Blog:

Source: https://habr.com/ru/post/449476/

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