RDB Archive Engine Service

The RDB archive engine reads samples from PVs and writes them to an RDB. The RDB may be MySQL, PostgreSQL or Oracle. For smaller setups and to get started, MySQL is very straight forward and will be described in here. For a production setup, PostgreSQL or Oracle can use partitioned table space that allows better data management over time. See https://github.com/ControlSystemStudio/phoebus/tree/master/app/databrowser-timescale for more on using PostgreSQL with the TimescaleDB extension to partition data and get optimized data retrieval.

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)


sudo yum install mariadb-server


sudo systemctl start mariadb

Set root password, which is initially empty:


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.

The provided database schema is meant as an example, concentrating on the essential tables. It uses a single large sample table. A production setup might prefer to partition the table by for example creating a new partition each month.

The schema as provided does not rely on table constraints. For example, while the chan_grp.eng_id should refer to a valid smpl_eng.eng_id, there may not be a foreign key constraint to enforce this. This has been done to minimize RDB overhead, using the database simply as “storage” and enforcing the correctness of the data inside the archive engine when it is importing a configuration or adding samples. For a production setup, you may want to add or remove constraints as desired.

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


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

<<<<<<< Updated upstream Extract configuration into an XML file:: =======

Extract configuration into an XML file:: >>>>>>> Stashed changes

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

For a description of the XML schema, see archive_config.xsd.

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

PV Name Details

The archive engine uses CS-Studio PV names. “ca://xxxx” will force a Channel Access connection, “pva://xxxx” will force a PV Access connection, and just “xxxx” will use the default PV type configurable via


Since EPICS 7, IOCs can support both protocols. “xxxx”, “ca://xxxx” and “pva://xxxx” will thus refer to the same record on the IOC.

The preference setting

org.csstudio.archive/equivalent_pv_prefixes=ca, pva

causes the archive engine to treat them equivalent as well. For details, refer to the description of the equivalent_pv_prefixes preference setting.

Run the Archive Engine

To start the archive engine for a configuration:

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

<<<<<<< Updated upstream

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 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. >>>>>>> Stashed changes 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.