Most binary data (files) that the Application Server stores, e.g. as data for instances of a property of type binary value or as data for a message attachment are not stored in the Application Server Database. The Application Server rather stores a reference to the file (a relative path) and additional meta data in the Application Server Database and the file itself on the file system.

Consistency between the files stored on the file system and the references in the database is managed by the Application Server. I.e. if a message attachment is deleted the corresponding file on the file system will be deleted too. Due to database transactions or other unforeseeable events there is still a chance that there are files on the file system that do not have a corresponding file link record in the database. The Application Server has a possibility to clean up these unreferenced files.

In case you need to recover your system from a backup there might be inconsistencies between the links stored in the database and the files stored on the file system, since these parts are backed up separately. The application server can detect and solve these inconsistencies,but still there is an extremely small chance of information loss, see backup for more information.

The directory where the referenced files are stored is defined in the instance configuration file (which is written during installation of the Application Server or the Application Server Instance). The directory given in the configuration is the directory as seen from the Application Server. The Application Server Database does not access these files directly. For performance reasons we recommend that the directory is either physically attached to the Hardware the Application Server runs on or connected via a really fast local network connection. The directory must be readable and writable by the Windows user that runs the Application Server.

In order to preserve information security we strongly recommend to grant write and read access to the directory used for storing referenced file sparingly. Only to the user that runs the Application Server should have read and write access. Additional read access may be needed for the user who runs the backup.

Files may be opened by the Application Server for preview generation, meta data or text extraction (see file storage for more details), the Application Server will never run executable files. Still we strongly recommend to use up to date security software (virus scan) to scan all files stored in that directory.

All files stored will be stored with a unique name (a Global Unique identifier) and without extension. The original name of the file is stored in the reference table in the database.