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

This section describes master/standby DCS Memcached instances.

Features

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

Master/Standby DCS Memcached 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 Memcached instance. In addition, data persistence is supported to ensure high data reliability.

    The standby node of a DCS Memcached 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. Multiple 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 HA for both data and applications.

Architecture of Master/Standby DCS Memcached Instances

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

Figure 1 Master/Standby DCS Memcached instance architecture

Architecture description:

  • VPC

    The VPC where all nodes of the instance are run.

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

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

    Use port 11211 to access a DCS Memcached instance.

Parent topic: DCS Instance Types