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Single-Node DCS Instances

Updated at: Mar 17, 2020 GMT+08:00

DCS provides single-node Redis or Memcached instances.

Features

  1. Low system overhead and high QPS

    Single-node instances do not support data synchronization or data persistence, reducing system overhead and supporting higher concurrency. QPS of single-node DCS Redis or Memcached instances reaches up to 100,000.

  2. Process monitoring and automatic fault recovery

    With an HA monitoring mechanism, if a single-node DCS instance becomes faulty, a new process is started within 30 seconds to resume service provisioning.

  3. Out-of-the-box usability and no data persistence

    Single-node DCS instances can be used out of the box because they do not involve data loading. If your service requires high QPS, you can warm up the data beforehand to avoid strong concurrency impact on the backend database.

  4. Low-cost and suitable for development and testing

    Single-node instances are 40% cheaper than master/standby DCS instances, suitable for setting up development or testing environments.

In summary, single-node DCS instances support highly concurrent read/write operations, but do not support data persistence. Data will be deleted after instances are restarted. They are suitable for scenarios which do not require data persistence, such as database front-end caching, to accelerate access and ease the concurrency load off the backend. If the desired data does not exist in the cache, requests will go to the database. When restarting the service or the DCS instance, you can pre-generate cache data from the disk database to relieve pressure on the backend during startup.

Architecture

Figure 1 shows the architecture of single-node DCS Redis and Memcached instances.

For DCS Redis 3.0 instances, you must use port 6379. For DCS Redis 4.0 or 5.0 instances, you can customize the port. If no port is specified, the default port 6379 will be used. In the following architecture, port 6379 is used. If you have customized a port, replace 6379 with the actual port.

Figure 1 Single-node DCS instance architecture

Architecture description:

  • VPC

    The VPC where all nodes of the instance are run.

    Single-node DCS Memcached instances do not support public access. The client and the instance must be in the same VPC with security group rule configurations.

    A DCS Redis instance can be accessed from a VPC or over public networks. The client can be deployed outside of the VPC and access the instance through the elastic IP address (EIP) bound to the instance.

    For more information, see Access Over Public Networks and How to Select and Configure a Security Group?

  • Application

    The client of the instance, which is the application running on an Elastic Cloud Server (ECS).

    DCS Redis and Memcached instances are respectively compatible with Redis and Memcached protocols, and can be accessed through open-source clients. For examples of accessing DCS instances with different programming languages, see Accessing a DCS Instance.

  • DCS instance

    A single-node DCS instance, which has only one node and one Redis process.

    DCS monitors the availability of the instance in real time. If the Redis process becomes faulty, DCS starts a new process to resume service provisioning.

    DCS Memcached instances are accessed through port 11211. DCS Redis instances are accessed through port 6379.

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