Database records (DB)

DBRC treats DL/I, Fast Path, and HALDB (High Availability Large Database) database records differently.

These types of records, their treatment, and contents are explained as follows:

DL/I database records
A DB record identifies a database that is registered and whose recovery is under the control of DBRC. This record contains information about the database and related recovery information including:
  • Database name
  • Database type
  • Share level of database
  • List of subsystems using the database
  • Extended Error Queue Element (EEQE) counter
  • IRLM identification of the first subsystem that authorized the database (if IRLM is used)

A DBDS record identifies a DBDS whose recovery DBRC is to control. This record contains information about the DBDS (such as its data set organization) and related recovery information including:

  • Name of the CA group to which the DBDS belongs
  • Maximum number of image copy data sets to be maintained for this DBDS
  • Indication of whether image copy data sets are to be reused
  • Period of time that image copy data sets are to be maintained for this DBDS
  • Name of the implied skeletal JCL default member
  • Extended Error Queue Elements (EEQEs)
  • Names of the members of the partitioned data set of skeletal JCL to be used in order to generate JCL for utilities that are run for this DBDS

To describe DL/I databases and DBDSs, DBRC maintains logically related records, as shown in the following figure.

Figure 1. DBRC DL/I records
begin figure description - A rectangle representing a DB record for each database is joined by a line to another rectangle that represents a DBDS record (one for each DBDS). There can be multiple DBDS records. end figure description
HALDB records
From a RECON data set perspective, HALDBs consist of a HALDB master (TYPE=HALDB) and one or more HALDB partitions (TYPE=PART).

The following figure shows the relationship of the RECON data set records that represent a HALDB.

Figure 2. Record structure for a HALDB in the RECON data sets
begin figure description - A HALDB Master DB record is joined by a line to a partition record (or partition records). The partition records are described in the following sections. end figure description
HALDB Master (DSPDBHRC)
The RECON data set stores information pertaining to the entire HALDB by using a DB header record. The DB header record includes the following:
  • HALDB master name
  • Global DMB number
  • Current change version number
  • TYPE=HALDB
  • Data sharing level
  • Recovery group
  • HALDB Partition Selection exit routine name
  • Database and data set organization
  • Maximum data set size for OSAM data sets
  • Partition ID of the latest partition defined
  • Recoverability of the HALDB
  • Number of partitions in the HALDB
  • Capability for online reorganization
  • Number of data set group members

The TYPE=HALDB DB record stores information about the HALDB. Applications conduct DB activity at the HALDB master level; DBRC conducts the DB activity at the HALDB partition level. A subsystem authorizes a HALDB partition, not a HALDB master.

HALDB Partition
Each partition of the HALDB consists of the following RECON data set records:
  • Partition record (DSPPTNRC)

    DSPPTNRC contains information that applies to the individual partition. The HALDB Partition Definition utility displays the partition record information. The LIST command does not display the partition record.

  • Partition DB record (DSPDBHRC)
    DSPDBHRC accesses the HALDB at the partition level. Like the TYPE=IMS DB record, the DB record for the HALDB partition records all sharing and recovery information. The partition name sets the database name field in this record. TYPE=PART has been defined for this record. The following fields have the same settings for each partition across the entire HALDB:
    • Global DMB number
    • Data sharing level
    • Recoverability of the partitions
    • HALDB master name
    • Capability for online reorganization
  • Partition DBDS records (DSPDSHRC)

    Depending on the organization of the HALDB, there can be three types of DBDSs for each HALDB partition: data, index, and ILDS data sets. Multiple data DBDSs can exist, but only one of each of the others. Only data DBDSs can be recovered. The other DBDSs are rebuilt using the HALDB Index/ILDS Rebuild utility (DFSPREC0).

    Related reading: See IMS Version 15.5 Database Administration for information about the data set and DDN naming conventions for DBDS records.

Fast Path database records

To describe DEDBs, areas, and Area Data Sets (ADSs), DBRC has a logical structure of records, as shown in the following figure.

Figure 3. DBRC Fast Path database records
begin figure description - A DB record (for each database) is joined by a line to a DBDS record (for each area). There could be multiple DBDS records. end figure description

DBRC uses the DB and DBDS records to describe both DL/I databases and DEDBs; however, DBRC adds an ADS list to the Fast Path DBDS record giving information about each ADS. Each DEDB may contain multiple areas, and each area may contain up to seven ADSs.

The Fast Path DB record contains information similar to the information in a DL/I DB record, except that it describes a DEDB; and it does not contain a list of authorized subsystems. For Fast Path, this list is in the DBDS record, which is composed of an area authorization record and an area recovery record. The Fast Path DB record is displayed in the listing as the DBDS record.

Related reading:  See the sample RECON listing in IMS Version 15.5 Commands, Volume 3: IMS Component and z/OS® Commands.

When an area is registered in the RECON data set, it ensures that:

  • The area names in the DEDB are unique
  • The ADS DD names in an area are unique
  • No more than seven ADSs are defined for an area