Increasing maximum DB2 log capacity

The HCL Workload Automation DB2® database uses a transaction log the maximum size of which is fundamentally important for the successful running of JnextPlan on very large databases.

The default log consists of 40 primary log files, which are always present, and 20 secondary log files, created on demand. Each file is about 4 MB in size, so the maximum log capacity using all of the "secondary" log files as well as the primary files is (40 + 20) x 4 MB = 240 MB.

The log space used by JnextPlan is dependent on the size of the preproduction plan. Approximately every 1000 job stream instances generate transactions that occupy 1 MB of space in the log file. Thus, the log files by default have a maximum theoretical capacity of 240 000 job stream instances. However, in practice, you should allow for at least 25% more space than this algorithm indicates, so the capacity of the default log files is around 180 000 job stream instances.

If JnextPlan has neared or exceeded that level, you must make more log space available to DB2.

In addition to performing the above calculation, you can also determine the log space actually used by a specific instance of JnextPlan and base your log size requirement on that figure.