Bootstrap Entry missing - Revising MAXARCH Value

Problem:
There was a request to do Log Extract for analysing data changes that happened 14 days back. The Extract job failing saying the log datasets are missing. Recoverability and log analysis for 14 days will /should be available any time. And the log datasets were available on the MVS Catalogue.


Reason:
Printed the Bootstrap dataset and found the archive log had for only 12 days after major monthly flow completion. The DB2 DSNZPARM MAXARCH defines the number of log datasets entries to be maintained by the Bootstrap dataset. The maximum number of archive log including the remote copy data sets that DB2 keeps in the BSDS depends on the value of the MAXARCH subsystem parameter. The MAXARCH was set to value 1000 in the system. Everyday around 50 archive log datasets are generated and special month end / month begin processing creates more archive log datasets. We did analyse the reason the log generation and found it was valid as the data volume as increased in the account.

FIX:
We increased the MAXARCH Value to 2000. When DB2 comes up it reads BSDS dataset changing 1000 to 2000 will not consume noticeable CPU difference. The additional space needed will be in few tracks, as the current BSDS dataset are allocated with 65 Tracks, even doubling it should not impact space usage. Log datasets are be available on the system irrespective of them not present in BSDS as the retention period is 15 days so there is no difference on log datasets maintenance.

Lesson Learnt:
Always monitor the number log datasets generated in the system. Any sudden increase need to be analysed, if the increase is due data volume. Revise the MAXARCH Value so that at any point in time 15 days recoverability is maintained. Just for your information, this recoverability duration might vary account to account.