ZDU - Distributed Installation

As a system administrator, you use the Zero Downtime Upgrade to upgrade your AE system with no downtime. To do so, you have to set up a distributed installation. This ensures that a current and new versions are available to carry out the upgrade and that you can test if the system runs properly in the new version before finishing the upgrade.

Important!

  • Only use the ZDU to upgrade systems that were installed manually or test systems that were installed using the ONE Installer. You cannot migrate to a cointainer-based system nor upgrade a container-based system using the Zero Downtime Upgrade.

  • It is recommended to use a test environment before installing upgrades on your production system.

  • When upgrading to version 12.3 or higher, make sure you check the new server process port definition and check for incompatibilities.

    More information:

This page includes the following:

Overview

Two different modes are activated during the upgrade: the compatibility mode and the parallel mode.

  • Compatibility mode

    This mode is active during the whole upgrade process, even if you carry out a rollback. Certain system optimization functions are not available when in compatibility mode and the system performance is reduced by about a third.

    You cannot switch a work process (WP) to a dialog work process (DWP) while in compatibility mode.

  • Parallel mode

    This mode is only active when server processes from the current and new version are active at the same time. Current version work processes (WPs) may slow down until the upgrade is completed.

The parallel mode requires two separate installations in separate bin directories: one for the version from which you want to upgrade (current); the other for the version to which you want to upgrade (new). These installations can be on the same host (recommended) or on separate hosts.

You can then choose if you want to split or distribute an existing installation. You can also use a proxy. For more information, see Combine with a Proxy.

Important! You have to use the same INI file (ucsrv.ini, see Automation Engine) for the base and the target version, located in one directory only. When upgrading to versions 12.3 and higher, please check the new server process port definition and check for incompatibilities.

More information:

Split an Existing Installation

Splitting an existing installation allows you shut down one part of the system and upgrade it instead of upgrading the whole installation at once. This means that you shut down half of the server processes, upgrade those to the new version, and start them again.

Important! If you upgrade from version 12.3, you can use the ports that are already configured. However, if you upgrade from a prior version, make sure you check the new server process port definition and check for incompatibilities.

You have to use two separate bin directories.

Advantage:

  • Less time needed for configuring ports, as no additional ports are necessary.

Disadvantages:

  • Shutting down communication processes (CPs) results in agents and users connected to those CPs being disconnected.

  • System performance is reduced to half.

More information:

Distributed Installation

This setup is recommended if you have a very large number of agents. If you need help, please contact our support department. For more information, see Support.

Set up two separate installations of the AE system you want to upgrade (current version). You can set them up on the same host or on separate hosts.

While in parallel mode, server processes from the current and new version are active at the same time. This means that you have to configure double the amount of ports than usually necessary. These ports must be known to all clients that connect to a server process. If you upgrade from a version prior to 12.3, make sure you check the new server process port definition and check for incompatibilities.

You also have to make sure you create double the amount of MQ tables in the database.

Advantages:

  • Using this kind of setup lets users continue their work without being disconnected.
  • Agents can be phased out successively and connect to the new communication processes (CPs).

Disadvantages:

  • This setup requires more preparation time at first.
  • Additional ports are necessary, which have to be configured in Firewall and existing Proxies.
  • All ports have to be known to all existing clients before you start the upgrade.

More information:

Combine with a Proxy

You can execute the ZDU by using a Proxy.

The Proxy combines and reroutes Java communication process (JCP) connections, while agents just connect to the Proxy, using the ports or port ranges configured in it.

  1. Either split or distribute your existing installation as explained above.
  2. Configure the second system in the Proxy accordingly.
  3. The Proxy will then reroute connections to either the current or new version JCPs, as necessary.

Advantages:

  • You do not have to configure any additional ports, neither when you split nor when you duplicate your system.
  • The Proxy handles the connections and the agents are connected to whatever system and JCPs are active and in use, be it current or new system.

For more information, see About Proxy.

See also: