CM

Availability

This feature is available since MogDB 3.0.0.

Introduction

Cluster manager (CM) is a database management software, which consists of cm_server, cm_agent, om_monitor, cm_ctl. Its core features are as follows.

• cm_server

  Send commands (such as start, stop, status query, switchover and failover of database instances) to cm_agent on each node and receive responses;

  Receive the database instance status information reported by cm_agent on each node;

  Highly available arbitration of cm_server itself on each node;

  Highly available arbitration of database instances on each node.

• cm_agent

  Receive and execute commands from cm_server, such as start, stop, status query, switchover and failover of database instances;

  Monitor the status of the database instance running on the current node and report it to cm_server.

• cm_monitor

  Monitor the cm_agent service running on the current node to ensure its availability.

• cm_ctl

  Client tool for CM.

Benefits

It manages and monitors the running status of functional units and physical resources in a database system, ensuring stable running of the system.

Description

It supports customized resource monitoring and provides capabilities such as monitoring of the primary/standby database status, network communication faults, file system faults, and automatic primary/standby switchover upon faults. It also provides various database management capabilities, such as starting and stopping nodes and instances, querying database instance status, performing primary/standby switchover, and managing logs.

Enhancements

• CM Highly Available Self-Arbitration with embedded arbitration algorithms and logic that does not rely on third-party components to achieve arbitration;

• Customized Resource Monitoring.

Constraints

In scenarios where there are one primary node and one standby node, CM supports only basic capabilities, such as installation, startup, stop, and detection.

Dependencies

Highly available arbitration relies on DCF, DCC, and CBB components.