Help Center/ Distributed Cache Service/ User Guide (Paris Region) / Service Overview/ DCS Instance Types/ Master/Standby Redis
Updated on 2022-02-21 GMT+08:00
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Master/Standby Redis

Both DCS for Redis and DCS for Memcached support the master/standby instance type. This section describes master/standby DCS Redis instances. Three Redis versions are available for master/standby DCS Redis instances: Redis 3.0, Redis 4.0, and Redis 5.0.

Features

Master/Standby DCS instances have higher availability and reliability than single-node DCS instances.

Master/Standby DCS instances have the following features:

  1. Data persistence and high reliability

    By default, data persistence is enabled by both the master and the standby node of a master/standby DCS instance.

    The standby node of a DCS Redis instance is invisible to you. Only the master node provides data read/write operations.

  2. Data synchronization

    Data in the master and standby nodes is kept consistent through incremental synchronization.

    After recovering from a network exception or node fault, master/standby instances perform a full synchronization to ensure data consistency.

  3. Automatic master/standby switchover

    If the master node becomes faulty, the standby node takes over within 30 seconds, without requiring any service interruptions or manual operations.

  4. DR policies

    Each master/standby instance can be deployed across AZs with physically isolated power supplies and networks. Applications can also be deployed across AZs to achieve high availability for both data and applications.

Architecture

Figure 1 shows the architecture of master/standby DCS Redis instances.

To access a DCS Redis 3.0 instance, you must use port 6379. To access a DCS Redis 4.0 or 5.0 instance, 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 Master/Standby DCS instance architecture

Architecture description:

  • VPC

    All server nodes of the instance run in the same VPC.

    For intra-VPC access, the client and the instance must be in the same VPC with specified security group rule configurations.

    For details, see Security Group Configurations.

  • Application

    The Redis client of the instance, which is the application running on the ECS.

    DCS Redis instances are compatible with the Redis protocol, and can be accessed through open-source clients. For examples of accessing DCS instances, see Accessing an Instance.

  • DCS instance

    Indicates a master/standby DCS instance which has a master node and a standby node. By default, data persistence is enabled and data is synchronized between the two nodes.

    DCS monitors the availability of the instance in real time. If the master node becomes faulty, the standby node becomes the master node and resumes service provisioning.

    DCS Redis instances are accessed through port 6379 by default.

Parent topic: DCS Instance Types