RDB Archive Engine Service

The RDB archive engine reads samples from PVs and writes them to an RDB. The RDB may be MySQL, Posgres or Oracle. For a production setup, the latter two offer a partitioned table space that allows managing the data by time. For smaller setups and to get started, MySQL is very straight forward.

Once the RDB is configured with the archive table schema, the archive engine is used both as a command line tool to configure the archive settings and as a service to write samples from PVs to the RDB. You can build the archive engine from sources or fetch a binary from https://controlssoftware.sns.ornl.gov/css_phoebus

Install MySQL (Centos Example)

Install:

sudo yum install mariadb-server

Start:

sudo systemctl start mariadb

Set root password, which is initially empty:

/usr/bin/mysql_secure_installation

In the following we assume you set the root password to $root. To start RDB when computer boots:

sudo systemctl enable mariadb.service

Create archive tables

Connect to mysql as root:

mysql -u root -p'$root'

and then paste the commands shown in services/archive-engine/dbd/MySQL.dbd (available online as https://github.com/ControlSystemStudio/phoebus/blob/master/services/archive-engine/dbd/MySQL.dbd ) to create the table setup for archiving PV samples.

View Archive Data

The default settings for the Phoebus Data Browser check for archived data in mysql://localhost/archive. To access MySQL on another host, change these settings in your Preferences Listing

org.csstudio.trends.databrowser3/urls=jdbc:mysql://my.host.site.org/archive|RDB
org.csstudio.trends.databrowser3/archives=jdbc:mysql://my.host.site.org/archive|RDB

The MySQL.dbd used to install the archive tables adds a few demo samples for sim://sine(0, 10, 50, 0.1) around 2004-01-10 13:01, so you can simply add that channel to a Data Browser and find data at that time.

List, Export and Import Configurations

List configurations:

archive-engine.sh -list
Archive Engine Configurations:
ID  Name     Description        URL
 1  Demo     Demo Engine        http://localhost:4812

Extract configuration into an XML file:

archive-engine.sh -engine Demo -export Demo.xml

Modify the XML file or create a new one to list the channels you want to archive and to configure how they should be samples. For details on the ‘scanned’ and ‘monitored’ sample modes, refer to the CS-Studio manual chapter http://cs-studio.sourceforge.net/docbook/ch11.html

Finally, import the XML configuration into the RDB, in this example replacing the original one:

archive-engine.sh -engine Demo -import Demo.xml -port 4812 -replace_engine

Run the Archive Engine

To start the archive engine for a configuration:

archive-engine.sh -engine Demo -port 4812 -settings my_settings.ini

The engine name (‘Demo’) needs to match a previously imported configuration name, and the port number (4812) needs to match the port number used when importing the configuration. The settings (my_settings.ini) typically contain the EPICS CA address list settings as well as archive engine configuration details, see archive engine settings in Preferences Listing.

In a production setup, the archive engine is best run under procServ (https://github.com/ralphlange/procServ).

The running archive engine offers a simple shell:

INFO Archive Configuration 'Demo'
...
INFO Web Server : http://localhost:4812
...
>
> help
Archive Engine Commands:
help            -  Show commands
disconnected    -  Show disconnected channels
restart         -  Restart archive engine
shutdown        -  Stop the archive engine

In addition, it has a web interface accessible under the URL shown at startup for inspecting connection state, last archived value for each channel and more. The engine can be shut down via either the shutdown command entered on the shell, or by accessing the stop URL. For the URL shown in the startup above that would be http://localhost:4812/stop.