Ive seen a couple of questions recently about people wanting to change their active log size, because they were either too small, (causing very frequent checkpoints) - or too large - they were bigger than 3GB for V710 or 4GB for V8 and later.
Check your archive logs
Check your archive log parameters. You can use the cpf DIS ARCHIVE or the CSQY121I message at start up.
CSQY121I MQPA UNIT=3390, UNIT2=, ALCUNIT=TRK,PRIQTY=500, SECQTY=100, BLKSIZE=24576
- The primary size PRIQTY is the same size as the maximum active log being used.
- BLKSIZE is a good value for your disks. An efficient value gives you 2 records per track. An inefficient value can waste up to half a track.
You can set these by using the SET ARCHIVE command, or csq6arvp and regenerate the zparms module.
Check the archive log name with your storage management team.
CSQY122I MQPA ARCPFX1=SCENDATA.D1, ARCPFX2=SCENDATA.D2, TSTAMP=YES
The archive logs should be allocated in a storage pool with enough space to hold at least a days worth of archive logs. You do not want to run out of space for archives.
Add new active logs
You will need to restart the queue manager to delete old logs.
Define your new logs and format them, you can dynamically add the logs using the DEFINE LOG command. You can issue this command at any time.
For example add logs log11, log12, log13
It is good practice to have enough active logs for a whole day's worth of data - in case archiving has a space problem.
Deleting the old active log data sets.
Issue the cpf ARCHIVE LOG command to switch logs until one of your new logs is the current active log
Shut down the queue manager cleanly.
Print out the BSDS ( in case you need to add the logs back in).
It is good practice to backup your pagesets - in case you need to recover a page set. If you need to use a previous backup - you will have problems because the logs will not be available in the BSDS.
Use CSQJU003 to delete the old logs see here.
Delete logs1, log2, logs3.
Restart the queue manager.
You can now add new logs log1,log2 and log3 ( and delete log10, log11, and log 12).