hisCollectWriteFreq

This tag configures how long to buffer collected history items in memory before flushing them to the historian. If this tag is missing, then collected items are immediately flushed to the historian and to disk. But when this tag is configured with a duration number, items are be buffered in memory and then written to the historian in batch. Batch writes enable more efficient compression of the history data and allows you to tune how often data is fsync'ed to disk.