How many historical data sets should you allocate?
Default customization provides for 3 data sets. When a data set is full, the historical recorder uses the next data set until that one is also full, and so on. When all the data sets are full, recording begins again with the first data set and the data is overwritten.
To determine the appropriate number of historical data sets for your site, collect sample data for one hour and then allocate the data sets according to how many hours worth of data you want to collect.
You can use the DSLIST view to add historical data sets dynamically, as described in Adding a historical data set dynamically.