The software product MAREN is provided to assist systems support in the management of tapes in the data center. MAREN stores its information about tapes in an ISAM file, the MAREN catalog.
Without MAREN it is not possible to work with storage locations (see "Device selection mechanisms for tape devices").
MAREN catalog
To keep the information in the MAREN catalog up to date at all times, the MAREN system is linked to BS2000. MAREN registers every DMS access. The MAREN catalog is updated each time a tape is processed.
The MAREN catalog is based on the volume serial numbers (VSN) of the tapes. The volume serial numbers must be unique, but require no special numbering concept.
Tape assignment and automatic initialization
An important component of the MAREN system is the automatic free-tape assignment facility MARENUCP. In the event of an unspecified tape request (“SCRATCH” tapes), for example, free tapes can be automatically assigned from the MAREN tape pool. At the same time, the processed tapes are marked as reserved in the MAREN catalog.
MARENUCP checks whether a tape that has been requested and mounted by the operator has to be initialized. If necessary, initialization is first performed before reservation and assignment take place.
Interfaces for BS2000 tape processing
In magnetic tape reservation and processing via the BS2000 Data Management System, the MAREN system is automatically activated for the following tasks:
Access authorization check
Availability check
updating of archive entries
Output of transport messages
Insertion of device parameters
Invocation of these test routines may be triggered by the following events:
reserving a tape
creating a TFT entry
opening a file
changing reels
closing a file
releasing a tape
Access authorization check
Before a tape is processed, MAREN checks whether the caller is authorized to access the volume. The following conditions must be met before each access:
If the tape is assigned to a foreign user ID, it must possess the attribute USERACCESS=*ALL-USERS in the MAREN catalog (exception: callers under TSOS).
If the tape is protected by a password, this password must have been specified.
If the tape is associated with an ARCHIVE directory , this tape can only be accessed with ARCHIVE.
For output to tape, write access must be permitted; the FOREIGN-READ-ONLY attribute must not be present in the MAREN catalog (exception: callers under TSOS).
For output to tape the file expiration date must be smaller than or equal to the current date.
If MAREN exit routines are being used, they must permit access to the tape.
If any of these conditions is not met, access to the tape in question is refused and a corresponding message is issued.
Availability check
Before allowing access to a tape, MAREN checks whether the following conditions for the availability are met:
The VSN of the tape exists in the MAREN catalog.
The VSN designates a tape according to the DEVICE-TYPE attribute.
The tape has not been lent out.
The tape has been reserved for the caller.
The tape is available in the local data center, i.e. the storage site defined in a special field of the archive entry is not marked “remote” in the storage-site table.
The tape is not being processed on another system (the check whether processing is taking place on the local system is performed not by MAREN but by BS2000.)
In the INPUT processing mode (except for access via ARCHIVE), the file names in the MAREN archive entry coincide with those in the TFT. Name portions denoting the catalog ID, user ID and version are ignored.
Detailed descriptions of the installation and use of MAREN in the data center can be found in the “MAREN” manuals [31].