Emerson Exchange 365

• Not Answered

Continuous Historian Storage limited to 10 GB - why?

Today I used the DeltaV "Continuous Historian Administration" application to convert an exported (archived) data set to "create an extended history data set".

It worked and I was able to look at trends from that time period. The other active data sets still appear to be there. Which causes me to wonder, why is the DeltaV historian limited to ca. 10 GB of history? The disk capacity on the stock Dell server we're using has about 1.4 TB of free disk space.

• DeltaV Historian

John Rezabek

• 15 Feb 2018 7:34 PM
• Cancel

2 Replies

• kathrynpate

  

  • 15 Feb 2018 7:50 PM

  I asked this question at the last Exchange, in the Historian Product Roadmap. My plant's deltav system wasn't set up with good data compression so we only get 20 days in our PHV trends (this is up from 11 days). I'd like to see an option to increase the size. I think most plants rely on a plant historian and forget about the operator stations.

  Kathy Pate

  Toray Carbon Fibers America

  Decatur, AL 35601

  kathy.pate@toraycma.com

  • Cancel
• Andre Dicaire

  

  • 15 Feb 2018 8:54 PM

  Great Question John. The 10G limit comes from when Continuous Historian was initially created, v7.3.1, and when Disk space was premium. Not to mention the consequence of running out of diskspace. Unfortunately, the limit has remained and I don't think anyone can explain it's validity in todays hardware.
  
  The limit applies to the current Data Sets, which are created and removed over time. This is sort of like having a number of PI Data Archives in the archive rotation. This limits your disk consumption to the defined number and size of Archive files, but also limits the time you can go back into. With PI, you can add more archives which effectively allocates more disk space and therefore longer history.
  
  With continuous historian, the Exported Datasets can be converted as Extended Datasets and registered for viewing. This disk space is above and beyond the 10Gig limit for managing the current datasets. There is no limit on the number of data sets you can register, or the size of them. In fact, if you created data sets that rolled over every day, you could have hundreds of current datasets within the 10 Gig limit. If the data sets were 1 month, (30 times bigger than 1 day), you'd have 30 times fewer datasets in the 10 Gig limit, but could still add extended datasets each of 1 month of Data, until you ran out of diskspace. Hmm, 1.8TBytes of disk space on a RAID10 Appstation with 6X600 Gb drives...
  
  The UDEP group was collecting information on this topic at the last exchange, and I did what I could to highlight the benefit to users of either removing this limit, or making it configurable based on user available diskspace. Another approach would be to create an automatic conversion of Current Datasets to Extended Datasets so users don't have to manually deal with this 10Gig limit.
  
  So I'd encourage you to make your desires known to the UDEP committee on why this should be changed.

  Andre Dicaire

  • Cancel