1. A computer-implemented method of archiving data values from a real-time database in a first historian system and in a second historian system, wherein each of the first and second historian systems includes a short-term repository and a long-term archive, comprising: identifying one or more data values in the short-term repository of the first historian system, wherein each of the data values are stored in the respective short term-repositories of the first and second historian systems as a tag that includes a timestamp, a tag ID identifying a monitored parameter in the real-time database, and a value for the monitored parameter; copying the tags storing the one or more identified data values from the short-term repository of the first historian system to the long-term archive of the first historian system; upon determining that the long-term archive of the second historian system is available, copying the tags storing the one or more identified data values from the short-term repository of the first historian system to the long-term archive of the second historian system; and upon determining that the long-term archive of the second historian system is not available, setting a flag in a mask file for each tag ID present in the tags storing the one or more identified data values.