Recovery period of image copy data sets and GENMAX
When you register a DBDS in the RECON data set, you specify the maximum number of image copy generations for DBRC to record with the GENMAX parameter of the INIT.DBDS command. When this number is exceeded, DBRC discards the information relating to the oldest image copy.
For example, if you take image copies daily and want to keep four days of back level image copies, specify a GENMAX of 4. However, in some emergency situations, you may take backup copies more frequently, possibly three in one day.
To prevent DBRC from discarding information relating to the earlier copies, specify the optional recovery period parameter (RECOVPD) to indicate the number of days you want information retained. If the GENMAX limit is reached, but the RECOVPD for the oldest image copy record has not expired, DBRC issues a warning message (DSP0065I), and does not discard the record. If the DSP0065I warning message appears frequently, you might need to tune the GENMAX or RECOVPD values with the CHANGE.DBDS command.
A recovery period is the minimum amount of time that information is maintained in the RECON data set. For example, if the recovery period of a DBDS or DEDB area is 14 days, DBRC maintains sufficient recovery-generation information for at least 14 days.
If both GENMAX and RECOVPD have been specified for a DBDS or DEDB area, DBRC considers both when deciding whether to reuse or delete an image copy data set.
The following table shows the results of GENJCL.IC processing when both GENMAX and RECOVPD have been specified for a DBDS or area defined with the REUSE parameter.
| Number of Image Data Sets | Number of In-Use Image Copies | Age of Oldest Image Copy | GENJCL Result |
|---|---|---|---|
| =GENMAX | =GENMAX | <RECOVPD | Fail (DSP0063I) |
| >GENMAX | =GENMAX | <RECOVPD | Avail IC DS used (DSP0065I) |
| =GENMAX | =GENMAX | >RECOVPD | Oldest IC DS reused |
| >GENMAX | =GENMAX | >RECOVPD | AVAIL IC DS used |
The following table shows the results of running an image copy utility when both GENMAX and RECOVPD have been specified for a DBDS or area defined with the NOREUSE parameter.
| Number of Image Copies | Age of Oldest Image Copy | Utility EOJ Result |
|---|---|---|
| =GENMAX | >RECOVPD | Delete oldest image copy |
| =GENMAX | <RECOVPD | No delete (DSP0064I) |
| <GENMAX | N⁄A | No delete |
If you issue a CHANGE.DBDS command and specify new GENMAX and RECOVPD values that are less than the existing values, any used image copy data sets that are beyond the recovery period are deleted until the number of remaining image copy data sets equals the specified GENMAX value.
If you issue the DELETE.IC command, any specified image copy data set record is deleted regardless of RECOVPD or GENMAX.