When tapes are reserved and processed in BS2000 (NDM, DVS), MAREN automatically becomes active for the following activities:
BS2000 and MAREN work together when the following events occur:
occupying a tape;
creating a TFT entry;
opening files;
changing a tape;
closing files;
releasing a tape.
Some checks and tests can be disabled using MAREN parameters, see section "Setting MAREN parameters" (Configuration on the local system). The BS2000 checks are always carried out, independent of MAREN.
Access control
Before each access to a tape, a check is made as to whether the following conditions have been met:
If domains are being used the tape must belong to the domain to which the system also belongs, or the tape must belong to the standard domain *STD-DOM.
If the tape is assigned to a foreign user ID, the USER-ACCESS attribute must be set to ALL-USERS or FOREIGN-READ-ONLY (exception: TSOS).
If the tape is password-protected, the appropriate ADD-PASSWORD command must first be entered.
If the tape is assigned to an HSMS/ARCHIVE free pool *TSOS/<dir-name>, this tape may only be accessed using HSMS/ARCHIVE.
If, in the case of OUTPUT, the tape is assigned to a foreign user ID, the USER-ACCESS attribute must be set to USER-ACCESS=ALL-USERS (exception: TSOS).
If the tape is to be used for output operations, the file expiration date must be less than or equal to the current date.
If MAREN exits are being used, these must permit access.
If any of these conditions is not fulfilled, access is rejected and an appropriate message is sent to SYSOUT.
The information which is relevant for a tape in an HSMS or ARCHIVE run is noted in MAREN. This includes directory file, save file ID, subsave number, expiration date, request name, and job name. When the tapes are accessed under HSMS and ARCHIVE, the directory file and save file ID are checked. This is also the case when save files are updated and also when save files are restored or released.
If the tape has the attribute VOLUME-STATUS=FREE, implicit reservation is carried out (only for HSMS and ARCHIVE) provided that the following conditions are fulfilled:
The tape must be contained in the appropriate pool of free tapes (see section “Free pool”).
The tape must not be intended for the automatic free tape allocation facility MARENUCP (see the SECURE-FREE-VOLUMES statement).
The volume type must be permitted for new reservations (see the RESERVE-DEVICE-TYPES operand in the MODIFY-MAREN-PARAMETERS statement).
If the tape has the attribute VOLUME-STATUS=RESERVED or PRIVATE, the following conditions must be fulfilled:
If DIR=NONE applies, the tape must not be contained in a directory.
If
DIR=<file-name>applies, the tape must be assigned to the user’s own ID (exception: TSOS).The attribute FREE-POOL for the tape must match the existing free pools.
Availability checking
Before any access is made to a tape, a check is made to see whether the following conditions for availability are fulfilled:
The tape must be entered in the MAREN catalog. If domains are being used the tape must belong to the domain to which the system also belongs, or the tape must belong to the standard domain *STD-DOM. Exception: If the system-specific MAREN parameter FOREIGN-TAPE-CHECK=*NO is set the tape needs not to be entered in the MAREN catalog .
The tape must not have been exported.
The tape must have the attribute VOLUME-STATUS=RESERVED or PRIVATE.
The tape must be available locally, i.e. the location contained in the catalog entry field TEMPORARY-LOCATION must not possess the attribute TYPE=REMOTE in the location table.
The tape must not currently be in use on another system (the check as to whether the tape is currently in use on the local system is performed by BS2000, not by MAREN).
If the tape is to be used for input operations, the file names in the MAREN catalog entry and in the TFT must match. The catalog ID, user ID and version are ignored. This check is not carried out if the volume is accessed via ARCHIVE.
Updating of archive entries
The following catalog entry fields in the relevant catalog entry are updated when a tape is processed:
LAST-ACCESS-DATE (only for locations with operating mode MANUAL)
LAST-ACCESS-TIME
LAST-ACCESS-JOB-NAME
LAST-ACCESS-USER-ID
LAST-ACCESS-ACCOUNT
LAST-ACCESS-HOSTNAME
LAST-ACCESS-TSN
LAST-ACCESS-SNO
LAST-ACCESS-FUNCTION-NAME
LAST-ACCESS-FUNCTION-FLAG
CHECK-COUNT
DEVICE-TYPE
TEMPORARY-LOCATIONACCESS-COUNT
OPEN-MODE
DEVICE-NAME
In the case of OUTPUT, the following catalog entry fields are also updated:
CREATION-DATE (only if smaller than EXPIRATION-DATE)
CREATION-TIME
CREATION-JOB-NAME
FIRST-VOLUME
VOLUME-SEQUENCE
FILE-NAME
CREATION-CATALOG-ID
CREATION-USER-ID
CLOSE-INDICATOR
LAST-CLOSE-DATE
LAST-CLOSE-TIME
INITIALIZATION
EXPIRATION-DATE
FREE-DATE
In the case of an HSMS/ARCHIVE backup, the following catalog entry fields are also updated:
DIRECTORY-NAME (only when saved with directory) SAVE-FILE, SUBSAVE/SEQ, REQUEST-NAME (when saved with HSMS)
Outputting transport messages
If the tape is not yet located on the system (i.e. TEMPORARY-LOCATION is not equal to the local system name), the transport message MAR4164 is output to the console. This message includes information on the current location of the tape.
No transport messages are issued for tapes in whose catalog entries the location of an archive system (operating mode “ROBAR-1” or “ROBAR-2”) or an external location (operating mode “EXTERNAL”) is entered as the TEMPORARY-LOCATION.
Using the DEVICE parameter
When processing input tapes archived in the MAREN catalog, the user can omit specification of the otherwise mandatory DEVICE parameter (see the MAREN parameter DEVICE-COMPLETION).
Determining the archive number for a tape file
When MAREN is used, the archive numbers of tape files that were not cataloged in TSOSCAT can be determined automatically.
One of the following requirements must be met to permit this:
The tape file concerned is processed further on the system on which it was created.
Both systems, i.e. both the system on which the tape file was created and also the system on which it is to be further processed, are interconnected in the same MAREN catalog.
If either of these conditions is met, which is usually the case when a tape file is further processed in the same data center, the information required for the file assignment concerning the tapes to be used and their device type is located in the MAREN catalog and can be called from there.
It is thus no longer necessary for the user to specify the archive numbers and their device type. The file assignment may looks like this, for instance:
/IMPORT-FILE SUPPORT=TAPE(VOLUME=*ANY,DEVICE-TYPE=*ANY,FILE-NAME=TAPE.FILE)
BS2000 (DMS) passes the file name on to MAREN. If the MAREN catalog contains entries with this name, MAREN returns the archive number and device type of the tapes marked in these MAREN catalog entries to DMS (“volume substitution”). Using the information received from MAREN, DMS can complete the file assignment and request the required tapes.
One problem that may arise in connection with volume substitution is that the same file name, e.g. TAPE.FILE, may occur more than once in the MAREN catalog. This is the case if the same tape file was created at different times and using different tapes, and if the relevant tapes in the MAREN catalog have not yet been released. These individual versions of a file are not distinguished by the file name, as is the case with file generations, for example. By default, MAREN can select the latest (youngest) file version. However, it must also be possible to select a specific older file version.
Another potential problem lies in the fact that tape files cannot always be uniquely assigned to user IDs. This means that there may be several entries in the file catalog (TSOSCAT) for the same tape file in the BS2000.
For this reason, DMS only stores the max. 41-character file name without the user ID in the tape labels (HDR3 label) and, for the same reasons, the tape file names are not given user IDs in the MAREN catalog.
Volume substitution encounters problems at the latest when the file name involved has several entries in the MAREN catalog and the associated tape files were created under different user IDs. Selection based on the file version does not always provide a solution here, as the different tape files with the same name may easily refer to files with completely different contents (e.g. file $A.XY contains inventory data, and file $B.XY contains personnel data).
File version and user ID selection
The command ADD-MAREN-FILE-ENTRY selects a specific file version, taking into account the user ID.
The VERSION operand in this command is used in volume substitution to define which file version in the MAREN catalog is accessed in a subsequent IMPORT-FILE command (with VOLUME=*ANY) and thereby to determine which archive numbers are required for processing.
The USER-IDENTIFICATION operand is used when determining these archive numbers to specify whether only MAREN catalog entries of the user’s own ID or of foreign IDs are to be evaluated or if selection is not to be based on user IDs (a detailed description of the commands for processing MAREN-TFT can be found in the “MAREN User Guide ” [1]).