8 Replies Latest reply on Sep 21, 2009 4:39 PM by RJKSolutions

    Archive Compare Utility

    ematics

      Is there such a tool for verifying PI archives?

        • Re: Archive Compare Utility
          cescamilla

          There are no tools for verifying PI Archives against each other. And thesre are many things you may want to compare in a archive in order to call it "the same", one could be Binary comparison, another one could be significant data comparison, in some other cases a set of archives may have the same data than one other archive. This is just to name a few things.

           

          So, what is it exactly you need this for? Perhaps someone could suggest a way to do that programatically.

            • Re: Archive Compare Utility
              ematics

              I am looking for something to verify archives for testing in an HA environment. I have two scenario's to test;

               

              1. Interface Data sent direct to each archive using PIBuffSS

               

              2. PI to PI synchronised data which I know will fail replication testing, but I would like to understand the differences.

               

              I am sure there are solutions out there, but do not know what they are.

                • Re: Archive Compare Utility
                  hanyong

                  Hi Terry

                   

                  I agree with Cristobal about identifying what is the basis that you want to use as comparison in this case. Otherwise we can't proceed to talk about having a comparison method or utility here.

                   

                  Cristobal has suggested a couple of comparison basis. For most cases that I have encountered, Archive comparison or verification involves comparing archived value of tags for selected period of time. Usually sampling is involved as well, selected random periods of time. for comparison.

                   

                  Would that be something that you are looking at?

                    • Re: Archive Compare Utility
                      hanyong

                      If your intention would be to verify in terms of comparing archived value of the same tag on different servers, then a simple verification program can be written with PI-SDK or other data access methods.

                       

                      Unfortunately I don't have a ready-to-use utility available. What I have seen so far are created by other PI users.

                • Re: Archive Compare Utility
                  ematics

                  How would you suggest that tests be performed for cases where PI to PI has been used to synchronise data? PI to PI is an OSIsoft tool for copying data between servers, as this is supplied by OSIsoft then a tool should be available to test success or failure.

                   

                  I understand totally that PI to PI is not true replication, but there should be some similar between the archives for a Archive Compare test to deem to the overall success.

                    • Re: Archive Compare Utility
                      hanyong

                      I would say that this is dependent on the expectation of the users, because again success in this case can be interpret differently. Some users are only concerned whether data is updated on time and not too concerned about differences in data history.

                       

                      However if users are concern about archive verification, most of the time it would be a situation  where users want to ensure that data on both servers to be the same because the data is used for critical analysis.

                       

                      In this case, I would suggest the archive verification process gives a % match and identify where the data are not matching on both servers, so that it would facilitate the administrator to find out the reason for the mismatch, or take actions from there.

                      • Re: Archive Compare Utility

                        Hi Terry,

                         

                        You can compare records (you look up the RecNo attribute for your PItoPI tags) in archives using the archive walk, which is run via piartool i.e. "piartool -aw".  However, this is a manual process...unless OSI progress it further so it can be automated.  

                         

                        If you know your archive start & end times, you can check each archive in turn for your PI to PI points - using PISDK you can do this with minimum effort.  Obviously if you are comparing 100,000's of PI to PI points across a WAN you would need to consider performance.

                         

                        Can you wait for SSB, where these issues are supposed to be resolved..?

                      • Re: Archive Compare Utility
                        NLHMI3

                        Terry,

                         

                          We used a product from Magion (www.magion.nl) called "mu-HC" (Magion Utilities - History Compare) to validate the "equality" of our process control and office domain PI server archives which we keep synchronized using bi-directional PI-to-PI interfaces. The tool collects interpolated real-time values from both archives and checks whether the difference falls within the real-time accuracy bounds for the given point.

                         

                        Henk.