This page describes steps to take before starting a Rhino Element Manager upgrade.

Note that there is no specific need to take a backup of the Tomcat installation prior to starting the upgrade. The first step that orca will perform when issued the upgrade-rem command is to take a backup, which will be available at the end of the upgrade process.

Verify that REM is currently working on all hosts to be upgraded

On each host which is to be upgraded, log into the REM web application (or refresh the page if already logged in), and connect to one or more of your Rhino clusters within REM. This is to aid in troubleshooting connectivity issues after the upgrade, specifically to help distinguish between newly introduced issues and existing issues not related to the upgrade itself.

Note that when refreshing the REM web application, do a "hard refresh" (Ctrl+F5 in most browsers) so that the browser retrieves up-to-date information from the REM server rather than reloading from its cache.

Take note of all the web URLs used to connect to your existing instances of REM, or leave them open in browser tabs. This is to make it straightforward to check each instance of REM after the upgrade.

Ensure the REM hosts are configured as appropriate

Run the following command, passing in the hostnames of the REM hosts to be upgraded:

./orca --hosts <remhost1,remhost2,…​> status

You should see REM status information about all the REM hosts specified, such as

general =
  Server version: Apache Tomcat/8.5.29
  Server built:   Mar 5 2018 13:11:12 UTC
  Server number:
  OS Name:        Linux
  OS Version:     3.10.0-693.11.6.el7.x86_64
  Architecture:   amd64
  JVM Version:    1.8.0_162-b12
  JVM Vendor:     Oracle Corporation
catalina_base = /opt/tomcat/apache-tomcat-8.5.29
version =
plugins =
catalina_home = /opt/tomcat/apache-tomcat-8.5.29
backup_dir = /home/rhino/rem-backup
backups =
  (#1) 20181129-121625 contains REM: Plugins:sentinel-gaa-em-,sentinel-volte-element-manager-

Ensure the Apache Tomcat version, and path to the installation (listed under "catalina_home"), are correct.

Tomcat installation autodetection and specifying the installation path manually

orca tries to automatically detect the location of the Tomcat installation on each REM host, either based on the CATALINA_HOME/CATALINA_BASE environment variables as visible to the user that orca logs in as to the REM host, or (more commonly) based on the currently running Tomcat process, or by searching the HOME directory. If orca is not able to automatically detect these directories, then they can be specified via the --remote-tomcat-home and --remote-tomcat-base arguments passed to orca.

In the vast majority of Tomcat installations these two variables point to the same location, namely the root of the Tomcat installation under which REM has been installed. In this case it is only necessary to specify the --remote-tomcat-home (CATALINA_HOME) argument, and orca will infer the same value for --remote-tomcat-base (CATALINA_BASE). Only in rare instances, such as two webservers running on shared Tomcat binaries on the same host, is it necessary use both. Refer to the Apache Tomcat documentation for more information on the difference between CATALINA_HOME and CATALINA_BASE.

As mentioned in Additional parameters passed to orca, these parameters can be passed to orca on all REM-related commands, and must be specified after the command.

Alternate manual upgrade procedure for non-Tomcat based installations

If you do not see a section in the status output titled REM, this is an indicator that this REM installation may not be based on (a supported version of) Apache Tomcat. This orca based procedure is only appropriate for upgrading REM and its plugins when installed on top of Apache Tomcat version 7 and above. For upgrading other types of REM installation, refer to the manual REM upgrade procedure.

Record the current time

When orca backs up the current REM installation, it will move the backup to a directory with a timestamp based on the current time. Make a note of the current time, in order to be able to locate this backup if needed.

Verify disk space

Verify the disk space on the REM hosts to be upgraded, by running the df command on each host using orca:

./orca --hosts <remhost1,remhost2,remhost3,…​> run "df -h"

Ensure there is at least 200 megabytes of free disk space. Refer to this section if you need to clean up old backups in order to free disk space.

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