Joined: 06 Jun 2008 Posts: 8195 Location: East Dubuque, Illinois, USA
The ICFRU overview is pretty clear:
The Integrated Catalog Forward Recovery Utility (ICFRU) assists z/OS users in recovering a damaged catalog to a correct and current status. All types of catalog entries that may exist in the basic catalog structure of the integrated catalog facility are supported, including those for VSAM, non-VSAM, and generation data groups. A catalog to be recovered may have been shared by multiple systems. A master catalog may be recovered, provided it is not in use as a master catalog.
Within this appendix, the term "catalog" should be understood to mean "an integrated catalog facility catalog", that is, "a basic catalog structure or BCS" (not to include the VSAM volume data set or VVDS).
An error-free backup of an undamaged basic catalog structure is used as the base for recovery. Catalog changes logged as SMF (System Management Facilities) records are selected and applied to this backup to create a new image of the catalog as it should now exist. This image of the catalog can then be reloaded to produce a current basic catalog structure.
* Helps improve system availability by reducing catalog recovery time
* Supports all data set types — VSAM, non-VSAM, and generation data groups
* Supports recovery of catalogs shared by multiple systems
* Provides extensive diagnostic facilities
* Permits advance assessment of recovery completeness
* Provides for catalog forward recovery without user-written code
* Avoids catalog repair techniques requiring great technical expertise
* Supports standardization and rehearsal of backup and recovery procedures
* Permits non-disruptive testing of catalog recovery procedures
Most z/OS installations today depend heavily on the availability of catalog facilities for continued operation of batch processing, online systems, and time-sharing systems. An extended outage of a catalog can be extremely disruptive. While there are a number of programs available that can reload a copy of a catalog as it existed at some previous point in time, normal catalog usage cannot resume until it has been resynchronized with the data sets as they currently exist. Thus the need is for a facility that can quickly, and without great technical expertise, recover a catalog to a current and correct status, that is, to the point of failure.
The ICFRU provides the capability to recover a catalog to current and correct status quickly and easily. Combined with a regular program of catalog diagnostics and backups and proper recording, dumping, and tracking of data from the Systems Management Facilities (SMF), ICFRU can help shorten the time of a catalog outage and reduce the need to maintain a high level of technical expertise in catalog management.