VTOC Maintenance Utility (FDRABRM)

FDRABRM is an ABR utility program that makes modifications in the VTOCs of DASD volumes to enable ABR processing and request special ABR processing.

Why a VTOC utility

Before ABR processing of a DASD volume (other than Application Backup) can occur, a special DSCB (data set) must exist in the VTOC of that volume. This is known as the ABR Model DSCB; it is called a model since the data set has no space (0 tracks) assigned, just like the “model DSCBs” used with GDGs. ABR uses fields in the ABR Model DSCB to store processing options for the volume, and to record information about recent full-volume and incremental backups. FDRABRM can create and modify the ABR Model DSCB. The data set name of the ABR Model DSCB is FDRABR.Vvolser (the prefix FDRABR may be changed by your installation at the time that ABR is installed).

Information about recent full-volume and incremental backups of individual data sets is stored in the Format 1 DSCBs of those data sets. It is also possible to set special ABR processing options for specific data sets in the DSCB. FDRABRM initializes and sets the DSCB fields used by ABR.

FDRABRM statements

DEFAULT

Set defaults for the FDRABRM statements that follow as well as specifying the VMVALID operand. The DEFAULT statement is not documented in this manual, but it accepts many operands from the other statements, including CYCLE=, FORCE, GEN=, HIGHTHRESOLD=, LIST=, LOWTHREASHOLD=, ONLINE, RESERVE=, RETPD=, and RETPD2=. The DEFAULT statement can be used when you have several statements following that require the same operands; you can enter them once on DEFAULT and remove them from the individual statements. See member ABRMDEF in the FDR Installation FDRSAMP for the full documentation on the FDRABRM DEFAULT statement.

ABRINIT

Enables a DASD volume for ABR processing by creating the ABR Model DSCB and setting the initial processing options for the volume. ABRINIT can be executed either on a new volume that has just been initialized by ICKDSF, or on an existing volume that contains data sets. “ABR initialization” does not affect any data already on the volume.

MAINT

Changes the ABR processing options in the ABR Model DSCB.

REMODEL

Recreates the ABR Model DSCB when it is accidentally destroyed or improperly modified and re-synchronizes the generation and cycle numbers.

Important

Most of the functions of the ABRINIT, MAINT, and REMODEL statements may be conveniently executed using the ABR ISPF dialog (option A.I.8). This is the recommended method for initializing and maintaining ABR volume processing options. For more information, see FDRABRM-ISPF-Interface.

DSCB fields

In the Format 1 DSCB of each data set, ABR uses:

The Update Indicator (DS1DSIND) – A flag set by data management whenever the data set is opened for OUTPUT or UPDATE and reset by ABR when a data set is backed up by full-volume or incremental dumps.
The Last Reference Date (DS1LRDT) – Set by data management whenever the data set is opened, if it is already non-zero. Since the Last Reference Date is normally set to zero when a data set is allocated, FDRABRM has an option to set zero Last Reference Dates to today's date, to initiate updating of that field. However, the ABR DADSM Pre-processing exit (Dynamic-Installation-of-the-FDR-Exits) also sets the Last Reference Date to the creation date when the data set is created, so the FDRABRM function is usually not required unless the DADSM exit is not enabled.
Two additional bytes (relative locations 103 and 104) to store information about the ABR status of the data set.
If the OLDBACKUP option is enabled on the volume, DS1SYSCD to store information on previous backups.

ABR processing options

FDRABRM may be used to set these ABR options for an entire DASD volume:

Enable or disable archiving (DUMP TYPE=ARC).
Enable or disable Superscratch (DUMP TYPE=SCR).
Enable or disable recording of the location of backups other than the most recent (OLDBACKUP).
Volume allocation thresholds for ARCHIVE processing.

Undocumented functions

FDRABRM has several undocumented functions. They are rarely used and have been eliminated from the manual, although they are still accepted. Contact BMC Support if you have a need for these functions.

FDRABRM is capable of setting ABR options for individual data sets, such as “always backup”, “never backup”, and “never ARCHIVE”. Since the data set options are stored in the DSCB of the data set involved, the options are lost if the data set is deleted and reallocated. We recommend that you use other means to accomplish the same results, such as the ABR protect lists and SELECT statements in the ABR input. FDRABRM can also be used to change the “update” flag and last reference date in individual DSCBs, but this function is rarely needed. For these reasons, the SELECT statement for setting these options is no longer documented in the manual, although it is still accepted.

SMS considerations

The ABRINIT and REMODEL statements support the creation of ABR Model DSCBs on volumes managed by System Managed Storage (SMS) (see Working-with-System-Managed-Storage). The following rules and considerations apply:

Since the whole point of allocating an ABR Model DSCB is to put it on a specific DASD volume, the SMS Storage Group ACS routine is not called to select a volume. The volumes on which ABR Model DSCBs are created is selected based on the VOL=, VOLG=, or ONLINE operands, or DISKxxxx DD statements.
When creating an ABR Model DSCB on an SMS-managed volume a storage class name must be assigned. Your installation might want to set up its storage class ACS routine to assign an appropriate storage class to ABR Model DSCBs (data sets named FDRABR.Vvolser with zero space); in this case, no special operands are needed on the ABRINIT or REMODEL statement. For an example, see ABR Volume Selection in SMS-ABR-Support. If not, then a storage class must be assigned by the STORCLAS= operand of the ABRINIT or REMODEL statement; your installation's ACS routine may accept the requested storage class, or may change it to a different storage class. In these cases, the ABR Model DSCB is successfully created. It does not matter to FDRABRM what storage class is assigned, only that it is a valid storage class name.
Your installation's ACS routine may change the requested storage class to null (blanks) indicating that this data set should not be SMS-managed. If the target volume is SMS-managed, a storage class is required, so you must specify BYPASSACS on the ABRINIT or REMODEL statement to allow the ABR Model DSCB to be created with the storage class you specified (STORCLAS=).
The ABR Model DSCB on an SMS-managed volume may optionally have a data class assigned. The data class may be assigned only by the DATACLAS= operand; the data class ACS routine is not given control. The data class has no effect on the processing of the ABR Model DSCB; if specified, it is used only for documentation or reporting. A valid data class name must be assigned.
The ABR Model DSCB on an SMS-managed volume may optionally have a management class assigned. The management class may be assigned automatically by the ACS routine, or explicitly by the MGMTCLAS= operand (unless overridden by the ACS routine). The specifications in the SMS definition for the management class is not used by ABR for managing the ABR Model DSCB; the ABR Model DSCB is backed up on every incremental backup, and never archived. However, if your installation uses DASD management software that looks at the management class, the management class may be significant and should prevent the ABR Model DSCB from ever being migrated or deleted. A valid management class name must be assigned.