What Is DCS?

DCS for Redis

DCS for Redis supports Redis 4.0/5.0/6.0.

• DCS for Redis 3.0 is no longer provided. You can use DCS for Redis 4.0 or later instead.
• DCS Redis 6.0 instances are supported only in some regions.

Redis is a storage system that supports multiple types of data structures, including key-value pairs. It can be used in such scenarios as data caching, event publishing/subscribing, and high-speed queuing, as described in Application Scenarios. Redis is written in ANSI C, supporting direct read/write of strings, hashes, lists, sets, sorted sets, and streams. Redis works with an in-memory dataset which can be persisted on disk.

DCS Redis instances can be customized based on your requirements.

• DCS for Redis 4.0/5.0/6.0 basic

  Table 1 DCS for Redis 4.0/5.0/6.0 basic

  Instance type	DCS for Redis provides the following types of instances to suit different service scenarios: Single-node: Suitable for caching temporary data in low reliability scenarios. Single-node instances support highly concurrent read/write operations, but do not support data persistence. Data will be deleted after instances are restarted. Master/standby: Each master/standby instance runs on two nodes (one master and one standby). The standby node replicates data synchronously from the master node. If the master node fails, the standby node automatically becomes the master node. You can split read and write operations by writing to the master node and reading from the standby node. This improves the overall cache read/write performance. Proxy Cluster: In addition to the native Redis cluster, a Proxy Cluster instance has proxies and load balancers. Load balancers implement load balancing. Different requests are distributed to different proxies to achieve high-concurrency. Each shard in the cluster has a master node and a standby node. If the master node is faulty, the standby node on the same shard is promoted to the master role to take over services. Redis Cluster: Each Redis Cluster instance consists of multiple shards and each shard includes a master node and multiple replicas (or no replica at all). Shards are not visible to you. If the master node fails, a replica on the same shard takes over services. You can split read and write operations by writing to the master node and reading from the replicas. This improves the overall cache read/write performance. Read/write splitting: A read/write splitting instance has proxies and load balancers in addition to the master/standby architecture. Load balancers implement load balancing, and different requests are distributed to different proxies. Proxies distinguish between read and write requests, and sends them to master nodes or standby nodes, respectively.
  Instance specifications	DCS for Redis provides instances of different specifications, ranging from 128 MB to 1024 GB.
  Open-source compatibility	DCS instances are compatible with open-source Redis 4.0/5.0/6.0.
  Underlying architecture	Containerized deployment on physical machines. 100,000 QPS at a single node for a Redis 4.0/5.0 instance, 150,000 QPS for a single-node Redis 6.0 basic edition instance, and 170,000 QPS for a master/standby Redis 6.0 basic edition instance.
  High availability (HA) and disaster recovery (DR)	All instances except single-node ones can be deployed across AZs within a region with physically isolated power supplies and networks.

  For more information about open-source Redis, visit https://redis.io/.

• DCS for Redis 6.0 professional edition

  Huawei Cloud DCS professional edition is completely developed by Huawei Cloud. This edition uses the multi-thread master-N*worker model instead of the conventional master-worker model, improving overall performance for n times. DCS professional edition is fully compatible with Redis engines, modules, and scripts in terms of scripts and event atomicity. Using the same hardware, this edition doubles the QPS of Redis, and reduces latency by around 60%.

  In versions earlier than Redis 6.0, a slow query often causes other queries to be delayed due to the single thread model. To address performance issues, the new edition has made a series of optimization based on a multi-thread model. Multi-thread concurrency has been improved for I/O and backend event processing; access to cached data is further accelerated through fair spinlock; expired keys can be removed twice as faster thanks to optimized algorithms; support for subkey expires also improves the read/write performance of big keys. As a result, the new edition is suitable in scenarios requiring high single-node performance, such as trending topics and livestreaming events on the Internet.

  Table 2 DCS for Redis 6.0 professional edition

  Instance type	DCS for Redis 6.0 professional edition includes performance and storage sub-editions. Only master/standby instances are available. The professional (storage) edition uses memory and SSD disks. Each master/standby instance runs on two nodes (one master and one standby). The standby node replicates data synchronously from the master node. If the master node fails, the standby node automatically becomes the master node. You can split read and write operations by writing to the master node and reading from the standby node. This improves the overall cache read/write performance.
  Instance specifications	8 GB, 16 GB, 32 GB, 64 GB
  Open-source compatibility	Fully compatible with Redis 6.
  Underlying architecture	Deployed on VMs. 400,000 QPS at a single node.
  HA and DR	All instances except single-node ones can be deployed across AZs within a region with physically isolated power supplies and networks.

DCS for Memcached (Discontinued)

DCS for Memcached is no longer provided. You can use DCS Redis instances instead.

Memcached is an in-memory key-value caching system that supports read/write of simple strings. It is often used to cache backend database data to alleviate load on these databases and accelerate web applications. For details about its application scenarios, see Memcached (Discontinued) Application Scenarios.

In addition to full compatibility with Memcached, DCS for Memcached provides the hot standby and data persistence.

For more information about open-source Memcached, visit https://memcached.org/.