PI to PI source data

PI to PI can gather data from the snapshot at the source server or from the archive at the source server. You must select the source most appropriate for your needs and expectations. Gather data from the snapshot if your system requires frequent updates and current data. Because snapshot data is not compressed, archives might vary slightly among servers. Gather data from the archive if your system requires identical data at all servers, such as for detailed analysis. A point's scan class determines the method used.

If PI to PI gathers snapshot data, choose a fast scan rate. PI to PI requests updates like any other client. The large amounts of data typically requested by PI to PI can overwhelm PI Update Manager. A faster scan rate clears the subsystem and avoids memory issues. Also, if PI to PI gathers snapshot data, then you must configure compression at the target server.

If PI to PI gathers archive data, choose a longer scan rate, such as hourly or daily. Set the scan rate such that there is at least one value in the archive. A longer scan rate avoids clogging PI Archive Subsystem with many smaller queries. Also, because data in the archives has been compressed, you can set compression to zero or turn it off on the target server.