Filter
Top Products
Forward recovery
For VSAM files, you can use a forward recovery utility, such as CICSVR, when
online backout processing has failed as a result of some physical damage to the
data set. For forward recovery:
v Create backup copies of data sets.
v Record after-images of file changes in a forward recovery stream. CICS does this
for you automatically if you specify that you want forward recovery support for
the file.
v Write a job to run a forward recovery utility, and keep control of backup data
sets and log streams that might be needed as input. CICSVR automatically
constructs the forward recovery job for you, using an ISPF dialog interface.
Backward recovery
To ensure that VSAM files can be backward recoverable, you must consider the
following points:
v Key-sequenced data sets (KSDS) and both fixed- and variable-length relative
record data sets (RRDS):
– If the files referring to KSDS or RRDS data sets are designated as recoverable
with LOG(ALL) specified, CICS can back out any updates, additions, and
deletions made by an interrupted unit of work.
– For information about backout failures, see “Backout-failed recovery” on page
79.
v Entry-sequenced data sets (VSAM-ESDS):
– New records are added to the end of a VSAM-ESDS. After they have been
added, records cannot be physically deleted. A logical deletion can be made
only by modifying data in the record; for example, by flagging the record
with a “logically deleted” flag, using an XFCLDEL global user exit program.
See “Transaction backout” on page 74 for more information.
Basic direct access method (BDAM)
CICS does not support forward recovery for BDAM files. You can implement your
own forward recovery support using automatic journaling options.
Backout for BDAM data sets is the same as for ESDS data sets in that you cannot
delete records from the data set.
Defining files as recoverable resources
This section describes how to define the recovery attributes for files managed by
CICS file control.
About this task
You specify recovery options, including forward recovery, either in the integrated
catalog facility (ICF) catalog (if you are using DFSMS 1.3 or later), or in the CICS
FILE resource definition, as follows:
v If your VSAM data sets are accessed by CICS in RLS mode, the recovery
attributes must be defined in the ICF catalog.
v If your VSAM data sets are accessed by CICS in non-RLS mode, you can define
recovery attributes in either the FILE resource or the ICF catalog. If you use the
ICF catalog to define attributes for data sets accessed in non-RLS mode, CICS
126 CICS TS for z/OS 4.1: Recovery and Restart Guide
|
|
|