Spill files

Spill files buffer log records when there is a requirement to maintain the serialization of log records and records cannot be immediately processed.

Input logs contain many record types that are not relevant to change accumulation, such as checkpoint records and DB status records. Because these record types are not carried on the spill files, the definition for log unit of measure does not include them.

A log data set, particularly tape logs, can reside on multiple volumes. Estimating the percentage of update records for the logs requires site specific knowledge of the database and transaction types that are typically being processed.

When converting estimates of spill file size to actual space values, the spill file BLKSIZE must also be considered. The default block size of 32760 might not be optimal for some DASD devices. Using a smaller but more track efficient size can affect the number of tracks required for spill files.

Examples in the following topics illustrate required work file sizes using input log data sets as the unit of measure: