Disk space requirements for database files

The Historian installation program adds the Runtime and Holding databases to Microsoft SQL Server by default. If you choose to store events to SQL Server, the A2ALMDB database is created.

Note: Historical plant data is not stored in the database files. This type of data is stored in special files called history blocks.

• The Runtime database stores all historian configuration data and classic event data. The information in the Runtime database is stored to disk as a database file named RuntimeDat_116_<server_name>.mdf. Its associated log file is RuntimeLog_116_<server_name>.ldf.

  The configuration data in the database file remains relatively static and usually never causes the file size to go above 20 MB. However, if you set up classic events, then records of event detections and the results of any data summaries or snapshots increase the size of the Runtime database file because the tables are filling up. Also, entries are created in the log file for event-related transactions. If the database files are set to auto-size, the Runtime database file expands to accommodate event-related data until the hard drive is full.

  Note: In a 2,000,000 tag system, 2.5 GB of space should be preallocated for data files when modification tracking is not used. When modification tracking is used, 20 GB should be preallocated.

• The Holding database temporarily stores tag definitions being imported from InTouch® HMI software. The information in the Holding database is stored to a database file named HoldingDat_116_<server_name>.mdf. Its associated log file is HoldingLog_116_<server_name>.ldf.

• The A2ALMDB database stores alarm and event data. The information in the A2ALMDB database is stored to a database file named A2LMDat_115_<server_name>.mdf. Its associated log file is A2ALMDB_LOG.ldf.

The Runtime and Holding databases are set to automatically expand at a 10% rate (the default).

You cannot change these defaults during the installation. The databases can be resized later using Microsoft SQL Server utilities. For more information on sizing databases, see your Microsoft SQL Server documentation for guidelines.

Note: If you are upgrading a previous version of the Historian, the installation program needs space to save a copy of the old Runtime database while it creates the new one. To upgrade, the database space required is twice the size of the old database, plus the database size for the new install.