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 base and target version are available to carry out the upgrade and that you can test if the system runs properly in the target version before finishing the upgrade.

Important!

It is recommended to use a test environment before installing upgrades on your production system.
The password fields used in versions prior to 12.1 are still in use to allow potential rollbacks, given the entered passwords comply with the password rules. If a password exceeds 20 characters or contains a comma, it is no longer compliant with the rules prior to 12.1. In this case, the password is saved in the new fields using AES encryption. The password(s) in the old field remain unchanged. Additionally, the Login object has to be locked for editing by old user interfaces This is done by updating the field OH_AEVersion to 12.1. In case of a rollback, all new passwords which are not compliant with the old rules are deleted and the field OH_AEVersion is reset to 11.2. This action causes that the login objects are unlocked and can be edited with an older user interface. Also, older WPs can access them for processing.
When upgrading to this version, make sure you check the new server process port definition and check for incompatibilities.

More information:
- Types of Server Processes
- Checking for Incompatibilities

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 base and target version are active at the same time. Base 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 (base); the other for the version to which you want to upgrade (target). 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 this version, please check the new server process port definition and check for incompatibilities.

Important! It is not possible to carry out a Centralized Agent Upgrade parallel to a Zero Downtime Upgrade.

Split an Existing Installation

In most cases, this is the chosen solution.

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 target version, and start them again.

Important! When upgrading to this version, please 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.

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 (base version). You can set them up on the same host or on separate hosts.

While in parallel mode, server processes from the base and target 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. When upgrading to this version, please 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.

Combine with a Proxy

You can execute the ZDU by using a Proxy.

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

Either split or distribute your existing installation as explained above.
Configure the second system in the Proxy accordingly.
The Proxy will then reroute connections to either the base or target version CPs, 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 CPs are active and in use, be it base or target system.