This manual describes the functions of the Data Management System (DMS) of BS2000. DMS is an autonomous subsystem within BS2000. It forms the connecting link between the user-controlled accesses to data objects and the central device drivers of the base system. DMS in turn makes use of certain services offered by the base system.
DMS provides support primarily for data processing on public volume sets (often abbreviated to “pubsets”).
Individual disk volumes are grouped together in a pubset. In addition to the home pubset, which accommodates all the files needed for the session, further pubsets can be added (imported) to the system. The system administrator can assign user IDs and thus the data of the users to the various pubsets in such a manner that a favorable distribution is achieved for system operation. Performance and availability are decisive criteria in this context.
For the “normal” user of BS2000, this means: unless he explicitly requests private volumes, all of his files are created on the pubset which systems support has defined as his default pubset. He does not need to request volumes or devices. DMS also manages his memory requirements.
An entry in the SYSSRPM user catalog is kept in each pubset for each user who is authorized to access this pubset. The files for the users are maintained in the TSOSCAT file catalog of the pubset. All user files are uniquely identified by the user ID and the catalog ID (the ID of the pubset on which the catalog is kept). At the same time, this ensures that file access is permitted only to the owner of the files unless he explicitly permits other users to access his files.
In addition to storing files on pubsets, DMS supports the user in managing data on private volumes (e.g. tape media) and on Net-Storage. Net-Storage is storage space which is connected to BS2000 via NFS. In every case the files to be processed must be cataloged in a file pubset's file catalog.
Functions of the Data Management System
The Data Management System (DMS) enables users to process their data by maintaining files and by using the various functions necessary for file processing. The DMS functions can be roughly divided into the following groups:
creating and managing files, including memory space management
managing catalogs
making files available and processing files using the access methods
assigning files to programs.
In addition to this, DMS permits the user to define data and file protection features at the file level. Data security is also supported by DMS, for example by setting locks during file access.
The functions of DMS are implemented via the Assembler interfaces described in the “DMS Macros” manual [1 (Related publications)] and the command interfaces described in the “Commands” manuals [3 (Related publications)].
Versions of related software products
References in the manual to the following software products always refer to the specified versions:
DAB V21.0
HSMS V12.0
HIPLEX-MSCF V21.0
SECOS V5.6