Best Practices Guide > Two-System Environment - Zero Downtime

Two-System Environment

Setting up a two-system environmentAn Environment consists of Deployment Targets which represent your endpoints. Different environments are used for different phases in the software delivery cycle, for example Development, QA, Staging, Production. An environment is typically set up once and used by several applications. for the Zero Downtime UpgradeA special function in the Automation Engine, which is meant to enable system upgrades between major versions, minor versions or service packs without the necessity of closing down the AE system at any point during the upgrade. is the best practice in order to have a base and a target version system ready to upgrade and test properly.

Notes

In the documents pertaining to the ZDU, all references to base and target system also mean base and target version.

Two special modes exist for this upgrade functionPre-defined run book template in the Automation Engine. One single step only, e.g. Start Windows Service, Copy file,…, the compatibility mode and the parallel mode.
Compatibility mode:
This mode is started as soon as you choose the option BEGIN from the ZDU wizard. In this mode, which is in effect until you choose the option FINALIZE, certain system optimization functions are not available. Also system performance will be reduced noticeably.
Parallel mode: A mode during the upgrade when base and target version processes are active at the same time.

Whenever you upgrade your system, Automic strongly recommends using a test system for extensive testing before installing upgrades on your production system.

General

In order to be able to seamlessly upgrade the Automation EngineThis component drives an Automation Engine system and consists of different types of server processes. without any downtime, using the Zero Downtime Upgrade function, you have to set up two separate installations. They serve to ensure that a base and target version system are available for conducting the upgrade and testing the proper running of tasks and jobs in the target version.

As base and target version CPs/WPs will be active in the parallel mode, you have to set up two separate systems in separate bin directories, one instance of the version you want to upgrade from (base), another of the version you want to upgrade to (target).

These may be two installations on:

  1. the same hostComputer, target system. (recommended)
  2. two separate hosts

You can use 1. or 2. with a ProxySeparate Automic product that can be used as an additional service program in combination with the Automation Engine. Combines and reroutes CP connections., details you find below.

The two alternatives can be realized using either two new AE installations or an existing AE system by duplicating or splitting it.

You have to use the same ucsrv.ini for base and target version, located in one directory only.

 

Below you find a more detailed description of how to set up the respective AE systems.

I. Two-System Environment - Two Separate Installations

  1. Set up two installations of the AE system you want to upgrade.
    1. Use either the same host and set up two separate installations.
    2. Alternatively use two separate hosts and separate installations.
  2. You have to configure double the amount of ports than are usually necessary for the correct working of an AE system.
    1. These ports have to be known to any clients that are going to connect to a CP, therefore enter them either in the INI or the config file.
      This is necessary, because at some point during the upgrade base and target version CPs have to be active in a parallel mode at the same time.
  3. You also have to create double the amount of MQ1CPnnn and MQ2CPnnnn in the databaseA database is an organized collection of data including relevant data structures..

Advantages:

Disadvantages:

II. Two-System Environment - Split an Existing Environment

  1. Use two separate bin directories.
  2. Split an existing environment:
    1. In this case you use already configured and known ports.
    2. You would shut down half the system, before you start the target version CPs.

Advantage:

Disadvantages:

III. Combine with a Proxy

You can execute the ZDU by using the most hassle-free solution and run a Proxy.

The Proxy combines and reroutes CP connections, while agents just connect to the Proxy, using the ports or port ranges configured in it.

  1. You have to set up one of the environment variants explained above, use a two-system environment or split your existing environment.
  2. Configure the second system in the Proxy accordingly.
  3. The Proxy will then reroute connections to either the base or target version CPs, as necessary.

Advantages:

 

Illustration 1: Schematic representation of a Proxy-based two-system environment solution:

 

See also:

Upgrading an AE System

 


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