Rotating dignostic and administration notification logs (DIAGSIZE > 0) was introduced in DB2 LUW 9.7. This is not a dynamic parameter; the new value/behaviour will take effect only after an instance restart.
Below are the steps we need to follow to change this instance level parameter:
Step1: diagsize is an instance level parameter
db2 get dbm cfg | grep -i ‘DIAGSIZE’
step2: to change DIAGSIZE from “0” to “200 MB”
db2 update dbm cfg using diagsize 200
Step3: Bounce instance
There are two types of Diagnostic logs:
(a) db2<instance_name>.nfy => For use by database and system administrators
(b) db2diag.log => For use by IBM DB2 Support
The total size of the db2diag.N.log and db2<instance_name>.N.nfy files will not exceed the DIAGSIZE value in MB.
The partition ratio between the db2diag.N.log files and the db2<instance_name>.N.nfy files is approximately 90% to 10%. 90% of the DIAGSIZE value is assigned to the db2diag.N.log files and 10% to the db2<instance_name>.N.nfy files.