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Introducing the InterSync Technology
DSM manages files and folders as digital resources. In the DSM database, a digital resource record stores basic file information (file name, size, creation date, etc.) as well as various additional information—so called “metadata”— related to the file/folder (a thumbnail image, extended preview, and any other user defined data).
DSM distinguishes between two types of files and folders: production and archive. Normally, production folders/files are constantly modified by members of a production group and reside on file servers. In contrast to this, archive folders/files do not undergo any changes and reside in archive locations (CDs/DVDs/etc.).
The major function of InterSync is to monitor production folders and keep corresponding digital resource records in the DSM database up-to-date. As changes occur to the InterSync working scope (the part of the file system it monitors), InterSync performs the following operations on the database: addition, deletion and updating digital resource records.
Additionally, InterSync assists in cataloging existing archive folders/files so that they become registered in the DSM database and, thus, available for various operations such as searching, retrieving, etc.
In order to fully understand InterSync’s digital resource monitoring, synchronization, and cataloging capabilities, it is important to first review the services that make up the InterSync technology.
The InterSync File System Service
The first fundamental component of InterSync is the File System Service (FSS).
The File System Service (FSS) maintains the list of production and archive folders with which the DSM database should be synchronized.
The FSS scans production folders and periodically compares them with the DSM database. When differences are found (i.e. files/folders have been added, deleted, or modified on the file server(s)), the FSS recognizes that addition, modification, and/or deletion events have taken place and updates the database by adding/deleting the appropriate digital resource records and/or activating the MetaData Service.
Unlike production folders, archive folders are processed only once. To synchronize the database with the contents of the archive folders, the FSS performs additions of corresponding digital resource records, activates the MetaData Service, and then stops. No deletions are made. However, you may manually initiate repeated scan(s) of the archive folders.
Note: The above policy is used for cataloging purposes: it ensures that even if a file or folder was deleted from the archive folder, the corresponding digital resource still remains in the database. For example, if you utilize a transitional storage area and categorize it as an archive folder, every resource that appears in this location (to be later moved to an offline storage) will be registered in the database.
There are two modes of operation that the File System Service can use when scanning a folder:
Full Scan—When operating in this mode, the File System Service scans the digital resources stored in the folder and compares the information it finds to the digital resource records in the DSM database.
Journal Scan—When operating in this mode, the File System Service does not scan the digital resources stored in the folder; it instead scans the change journals maintained by Windows 2003 for each volume. These change journals record when files and folders are added to, deleted from, or modified on the server.
IMPORTANT! Although the Journal Scan mode is faster and uses fewer server resources than the Full Scan, it can only be used when the File System Service and the file server are located on the same Windows Server computer (volume change journals cannot be read remotely). For this reason, it is recommended that the File System Service be installed on every Windows 2003 computer operating as a file server.
The InterSync MetaData Service
The second fundamental component of InterSync is the MetaData Service (MDS).
The working scope of the MetaData Service for a particular database is limited to the list of folders maintained by the File System Service for the same database. The MetaData Service starts processing of a file/folder from its working scope in the following situations:
The File System Service recognizes an addition/modification of the file/folder and activates the MetaData Service to perform further processing.
The digital resource record corresponding to the file/folder has been added or updated manually using the DSM client application.
When the MetaData Service recognizes requests for processing from the File System Service and/or DSM client application, it obtains the basic file information and metadata (including an up-to-date thumbnail and extended preview) and updates the corresponding digital resource record in the DSM database.
note: The DSM system generates thumbnails and extended previews for each digital resource based on its file type (e.g. text file, folder, PICT file, BMP file, PDF, etc.). For information on thumbnail and extended preview generation methods, and instructions for specifying the way the DSM system should use these methods for each file type, please refer to “Setting Up File Types”of this guide.
In addition to obtaining the basic file information and standard metadata, the MetaData Service may be instructed to classify the digital resources according to the roles they play within your company’s digital workflow. For example, a file server folder containing digital resources may play the role of a Job folder or an Art catalog.
The major purpose of the digital resource classification is to extend the search capabilities of the DSM system: it is possible to create search routines (user and Global Finds) based on the digital resource roles assigned by the MetaData Service. Moreover, the defining condition of a role may be used to instruct the MDS to obtain custom defined metadata associated with the digital resources and reflect this information in the fields of the DSM database.
The InterSync technology provides for automated one-way synchronization of the digital resources residing on your file server(s) and other locations and the digital resource records of your DSM database(s)—changes in the file system are reflected in the DSM database in the following manner:
Addition—When a file or folder is added to the file system, the File System Service adds a new digital resource record to the DSM database and activates the MetaData Service to obtain the file/folder metadata and generate a thumbnail and extended preview for the resource.
Deletion—When a file or folder is deleted from the file server, the File System Service waits for a specified period of time, then deletes the corresponding digital resource from the database, removing the digital resource record itself as well as references to the digital resource from the file collectors. The Digital Resources Deleter component of the File System Service can be configured to exclude specified folders when deleting (for example, when digital resources are archived onto CDs and physically removed from the file server, it may be desirable to keep the digital resource information in the DSM system) and to avoid deleting digital resources from file collectors. It may also be configured to avoid deleting digital resource records altogether.
Modification—When a file or folder is modified on the file server, the File System Service activates the MetaData Service in order to obtain up-to-date file metadata and generate an updated thumbnail and extended preview for the corresponding digital resource.
note: One-way synchronization means that file server events are reflected in the DSM database, not vice-versa. For example, the manual deletion of a digital resource record from the DSM database will be recognized by the File System Service as a digital resource addition event (the file server now contains a file or folder that does not exist in the DSM database) and the digital resource record will subsequently be recreated in the DSM database. For this reason, it is recommended that manual additions and deletions of digital resource records not be performed for file server folders managed by InterSync.