EXTBKUP (Extract from Backup File)

The EXTBKUP function of DBUTLTY reads a backup file and writes extract of backup format data to the output data sets.

Important! Prior to the execution of the EXTBKUP function, one or more FILEOUT functions must have been specified. FILEOUT functions define which tables are extracted by the EXTBKUP function. See FILEOUT (Define Output Data Sets).

A backup file contains records for one or more tables, based upon the area or database content, and optional control statements provided to the backup utility. The EXTBKUP function can extract one or more tables from a backup file, as specified by the user. The function can also expand compressed data on the backup to a new backup file with no compressed records.

EXTBKUP with FORMAT=EXTRACT generates data in expanded form. An extract file is not compressed and contains no CA Datacom control information. However, backup files always contain control information and may or may not contain compressed data. Compressed data, if present, can be in the CA Datacom form or in a user compression form, such as the CA Datacom Presspack. EXTBKUP uses the control information on the backup file to know what tables exist, the row size, and compression options.

The FILEOUT function (see FILEOUT (Define Output Data Sets)) is used to define one or more output data sets for EXTBKUP. If the table is empty, FILEOUT creates a valid null output data set.

EXTBKUP usually writes each data record as a fixed-length record in a fixed-block format.

Output files have a block size as specified in the JCL or a default of the operating system maximum, based upon device type. TAPE is blocked up to 32767, and DISK is blocked up to 27998.

When using the EXTBKUP function, an error occurs after one the following scenarios:

no FILEOUT statements were provided, or if
The input file is not a valid CA Datacom backup file produced by r10 or later, that is, backups produced by CA Datacom releases before r10 are not supported.

EXTBKUP reads the control records at the start of the backup and edits them to see if the backup represents all tables selected by the FILEOUT statements.

Note: Tables are not required to have rows present.

The z/OS input concatenation of multiple individual backup files is supported by EXTBKUP.

Prior to the EXTBKUP function, one or more FILEOUT functions must have been specified to define which tables are extracted.