Tuning Performance › VSAM Data Set Tuning › Record Size Management › Exceptions

Exceptions

The following NDBs store historical records:

• Alert history ($ALERTH)
• File transfer events log (EVNTDB)

Because records are added and deleted in key sequence order, do not allocate free space for these NDBs. Also, do not reorganize them because the NDB feature, RIDREUSE, reclaims the space used by deleted records. You can monitor their sizes by defining VSAM alerts that are raised when a predetermined number of extents are allocated.