You can specify replacement checkpoint data set definitions to ease recovery from checkpoint I/O errors and the subsequent loss of checkpoint data set access. All 4 checkpoint data sets (NEWCKPTn and CKPTn) must have unique names. For checkpoint data sets residing on DASD, you can have the same DSNAME= value if the VOLser= specification is different. For checkpoint data sets residing on a Coupling facility structure, the STRNAME= parameters must be different. Specify replacement checkpoint data sets on either DASD or on Coupling facility, regardless of what has been specified on the CKPTn= parameters. Generally, replacement data sets are prefixed with SYSn to provide a complete data set name. For consistency in the following discussion, SYS1.REPLACE1 and SYS1.REPLACE2 are used for the NEWCKPT1= and NEWCKPT2= parameter specifications.

These replacement data set definitions can also be used in non-error situations, such as scheduled hardware maintenance. In both DUPLEX and DUAL mode, NEWCKPT1 provides the replacement definition for CKPT1 and NEWCKPT2 provides the replacement definition for CKPT2.