About Archives

Historian archives are data files, each of which contains data gathered from all data sources during a specific period of time.

Types of Archive Files:

  • machine name_Config.ihc: Contains information about the archiver, tag configuration, and collector configuration.
  • machine name_ArchiveXXX.iha: Contains tag data, where x is a number indicating the place of the file in a time-based sequence.

Creation of Archive Files

Archive files grow to a user-configured maximum size as data is recorded by the server. When data starts loading into an archive file, Historian will asynchronously create a new blank archive file. When the current archive file becomes full, Historian will immediately serve data to the newly created archive file. This significantly reduces archive creation and transition time. If the automatic create archive option is not enabled, however, you must create a new archive file manually.

Note: If the Automatic create archive option is not enabled and you do not create a new archive manually, or if the available disk space is less than the required amount of free disk space, a new archive will not be created.

Overriding Old Archive Files

If you enable the Overwrite Old Archives option, the system replaces the oldest archived data with new data when the latest archive default size has been reached. Since this action deletes historical data, exercise caution in using this feature. Be sure that you have a backup of the archive so that you can restore it later. Best practice is to create an additional archive to prevent premature loss of data due to overwriting. For example, if you want to save 12 months of data into 12 archives, create 13 archives.

During archiver startup and every 60 seconds while the server is running, Historian verifies that you have configured enough free disk space to save the archives, buffer files, and log files. If there is insufficient disk space, the Data Archiver shuts down and a message is logged into the log file. By default, you can view the Historian archiver log file in C:\Historian Data\LogFiles.

[03/03/10 15:28:41.398] Insufficient space available in [d:\Historian\Archives\] 
        [03/03/10 15:28:41.399] The server requires a minimum of [5000 MB] to continue 
        [03/03/10 15:28:41.679] USER: DataArchiver TOPIC: ServiceControl MSG: DataArchiver(DataArchiver)
        Archiver shutdown at 03/03/10 15:28:41.653   
        [03/03/10 15:28:41.807] DataArchiver Service Stopped. 
        [03/03/10 15:28:41.809] [d:\Historian\LogFiles\DataArchiver-34.log] Closed.