ABCs of z/OS System Programming Volume 3 - IBM Redbooks

7.21 Backup and recovery of CICS VSAM data sets
Backup tool DFSMSdss
Supports backup-while-open processing
BWO type TYPECICS allows to backup the data set
while it is open in CICS
BWO of forward recoverable data sets allows a
recovery tool to take this backup for forward recovery
Recovery of a broken data set
Non-recoverable data sets:
Lost updates, data in the backup can be inconsistent
Backward recoverable data sets
Lost updates, data in the backup are consistent
Forward recoverable data sets
No lost updates, data are consistent
Figure 7-29 Backup and recovery of CICS VSAM data sets
Backup tool DFSMSdss
DFSMSdss supports backup-while-open (BWO) serialization, which can perform backups of
data sets that are open for update for long periods of time. It can also perform a logical data
set dump of these data sets even if another application has them serialized.
Backup-while-open is a better method than using SHARE or TOLERATE(ENQFAILURE) for
dumping CICS VSAM file-control data sets that are in use and open for update.
When you dump data sets that are designated by CICS as eligible for backup-while-open
processing, data integrity is maintained through serialization interactions between:
► CICS (database control program)
► VSAM RLS
► VSAM record management
► DFSMSdfp
► DFSMSdss
Backup-while-open
In order to allow DFSMSdss to take a backup while your data set is open by CICS, you need
to define the data set with the BWO attribute TYPECICS or assign a data class with this
attribute.
► TYPECICS
Use TYPECICS to specify BWO in a CICS environment. For RLS processing, this
activates BWO processing for CICS. For non-RLS processing, CICS determines whether
Chapter 7. DFSMS Transactional VSAM Services 415