Disk Space Handling in zenon – FAQs Part 3

How can zenon proactively notify users when resources become too low?

Part 3 Hard Disk HandlingDue to the fact that Free disk space – database (%) is essentially just another zenon variable, you can easily add a Limit or Reaction Matrix which is capable of color changes, visibility, flashing, etc. when a certain condition is met.

For example, a limit could be created on the Free disk space – database (%) variable which returns true when the free disk space goes below 15%. When this occurs you can generate an Alarm and/or an Event. Furthermore, you can require that this specific Low Disk Space alarm is in a special class, and requires acknowledgement from a system administrator.

To go another step further, you can add an additional limit on the Free disk space – database (%) variable which returns true when, for example, free disk space drops below 10%. On this limit you might add a zenon Function type “Send a Message” which sends an SMS or Email notification to a specific user or group of users about this event.

How can zenon manage the disk space and remove old data?

The zenon Historian module offers built-in mechanisms which grant the capability to either delete old archive data, or evacuate/move archive data to another location after a specific time period has lapsed. If configured properly, zenon is even capable of re-reading this data back into Trends, Reports, etc., although it may no longer physically reside in the same directory or PC anymore.
Although the sophistication of the zenon Historian enables it to manage archived data, zenon will continue to accumulate Alarms and Events from the time the project is first started. To manage the historical Alarms & Events, zenon offers a ready-to-use function called File Operations in the Function Group -> Windows.

The File Operations function can be used to move or delete files either on a time schedule (zenon Time Control Module) or when a limit is breached (Limit Function or Reaction Matrix Triggered). The function must, of course, first be parameterized with the operation (Copy, Move, or Delete) and the source and target directories defined. The File Operations function also allows wildcards and time filters to be used, for example: all files in the format *.XML – that are older than 180 days – should be moved to a network file server at \\MyNAS.corporate.lan\zenonData\old_alarms.


Industrial operating conditions will fluctuate to a certain degree. Exact estimates of how frequently value changes will be received by the HMI/SCADA system next month or how many alarms will be generated next week are often difficult to make. This is further amplified when unsolicited communications are used and data is being generated based upon these unforeseeable value changes (e.g. alarms, events, etc.).

The tools we’ve discussed here help to give zenon users an insight of zenon disk space use and flexibility in handling it. In this way, zenon ensures that your HMI or SCADA application can continue to run in industrial environments with minimum IT monitoring and involvement.


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