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How to get your system uptime to the maximum.
NGA - High Availability Configuration (HAC)
This chapter provides an overview of the High Availability Configuration for redundant or non-redundant WinCC OA projects (High Availability Configuration - HAC) and explains the roles of the components etcd and Patroni, which are required to set up HAC.
Requirements
This chapter contains the requirements for NGA - High Availability Configuration (HAC).

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- Redundancy
  The high availability requirements of plant constructors and operators as well as the process and data security can be covered with the redundancy concept of WinCC OA.
- Redundant network connections
  In order to achieve a better fault tolerance WinCC OA Managers can connect to other WinCC OA Managers running on different computers via redundant network connections (this means connecting through two network connections (= IP connection)).
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  The alive mechanism in WinCC OA serves for connection controlling between the single managers. Each manager sends alive messages at definable intervals.
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  The identification caching provides you an advantage especially when using remote user interfaces and distributed systems. Identification caching allows the identification to be sent as “delta” instead of the whole identification. Thus, only the changes are sent by the Data and the Dist managers.
- System Dashboard
  The System Dashboard in WinCC OA provides a central overview of system status, performance metrics, and security aspects. It helps operators and administrators quickly view and assess important information.
- NGA - High Availability Configuration (HAC)
  This chapter provides an overview of the High Availability Configuration for redundant or non-redundant WinCC OA projects (High Availability Configuration - HAC) and explains the roles of the components etcd and Patroni, which are required to set up HAC.
  - Requirements
    This chapter contains the requirements for NGA - High Availability Configuration (HAC).
  - Installation and Configuration - Windows
    This chapter provides an overview of the installation and configuration steps for the High Availability Configuration (HAC).
  - Installation and Configuration - Linux
    This chapter provides an overview of the installation and configuration steps for the High Availability Configuration (HAC).
  - Failover and Recovery Scenarios
    This chapter explains the failover and recovery scenarios for the High Availability Configuration (HAC).
  - Update Scenarios
    This chapter describes the update scenarios for the High Availability Configuration (HAC).
  - Restrictions
    This chapter contains the restrictions for NGA - High Availability Configuration (HAC).
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Requirements

This chapter contains the requirements for NGA - High Availability Configuration (HAC).

The version requirements of the necessary software components for the HAC are listed in the table below for each supported platform.

Table 1. Requirements
Component	Windows	Red Hat	Debian
WinCC OA	Current version 3.21 of WinCC OA.
PostgreSQL®	The PostgreSQL® version 17 supported and delivered with WinCC OA.
PowerShell	7.5 or higher
Python®	3.13 or higher	3.9.21 or higher	3.11.2 or higher
Patroni	4.0.5	4.0.6	4.0.6
etcd	3.5.18	3.6.4	3.6.4