Limiting PPA archive size on disk without offload storage


For demo purpose, we want to install openPDC on some computers BUT limit the size of the PPA archive (around 1GB) because the objective is to make on-the-road presentations… not a real PDC application and we don’t want to fill those computer hard disk with full of useless historic archive.

In the openpdc configuration file, we found (in the section) the FileSize of each .ppa file (100MB) but could not locate maximum allowed space for total archive.

Would it be OK to use the “MaxHistoricArchiveFiles” set to 10 instead of -1 ( so 10 files of 100MB = 1GB) or is there an easier method to limit the global file size to be used by the archive ?

And, when the limit is reached, would the oldest one be remove (desired) or would the acquisition stop ?

Finally, is it better to set “ArchiveOffloadLocation” to “” or to “DELETE” ?



Hi Michel,

The MaxHistoricArchiveFiles will delete files from oldest to newest once the configured number of files has been reached. This would, indeed, be an effective way of limiting the size of the archive.

The ArchiveOffloadLocation is only used to handle files whose age has exceeded the ArchiveOffloadMaxAge property. If you do not want to offload your files, a value of "" or "DELETE" would both be appropriate for the ArchiveOffloadLocation.



I’d be interested in knowing more details how to configure the OpenPDC to limit the number of days available in the archive. I want to build a rolling archive of the last 30 days.
So far I tried to configure the historian connection string with:

  • MaximumArchiveDays=1,
  • ArchiveOffloadLocation=DELETE

But I can’t achieve the desired result. Could you help me locate the mistake I have

Best regards,

Try ArchiveOffloadLocation = *DELETE* - with asterisks.

Also, you can install the stand-alone openHistorian 2.0 ( for better performance than the built-in openHistorian 1.0 that comes with openPDC…


Hi Ritchie,

Thanks for the quick reply!
In trying to set up the openhistorian, I’d like to configure everything correctly, do you know where there is a guide to to do that?

In summary, I don’t want to store anything in the openPDC, only collect measurements, and redistribute them, and store 1 month (rolling) of data in the openHistorian.
I’ve been searching the discussion board here and on your github repositories, but can’t find a full step by step instruction on how to achieve that.

Following this:
I setup the internal subscription in openHistorian to get the openpdc data.
Also in OpenPDC I deleted the PPA in historian instances
Is any of it wrong?

Best regards

Here are sone docs for connecting openHistorian to openPDC:

Use port 6165 for openPDC data…