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| Persistent/Non-persistent messages and /var/mqm/log |
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| w33f |
 Posted: Mon May 05, 2014 4:42 pm Post subject: Persistent/Non-persistent messages and /var/mqm/log |
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Novice
Joined: 07 Nov 2013
Posts: 17
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Hi all
I had a question re: the usage of /var/mqm/log. My understanding is that persistent messages will always be written into /var/mqm/log, and non-persistent messages will be written to memory and if that runs out, it will be stored in the queue directory of the /var/mqm/qmgrs/QMGR_NAME.
However I've checked on a few different qmgrs for which I know there are only non-persistent messages being used and I can still see the files in /var/mqm/log getting updated.. So does that mean non-persistent message data is still written to /var/mqm/log? or is there some other kind of metadata being written?
E: Was just reading the info on the output of dmpmqlog here: https://publib.boulder.ibm.com/infocenter/wmqv7/v7r0/index.jsp?topic=%2Fcom.ibm.mq.amqzag.doc%2Ffa14810_.htm
So it seems from that that only persistent message data is logged.. I guess my question is what other data is logged related to messages/qmgr activities (apart from startup/shutdown) that could cause the logs to keep being updated when there are no persistent messages being used? |
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| fjb_saper |
| Posted: Mon May 05, 2014 7:37 pm Post subject: |
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Grand High Poobah
Joined: 18 Nov 2003
Posts: 20756
Location: LI,NY
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I believe it says somewhere in the documentation that messages under syncpoint are also written to the log, at least for the duration of the transaction... Plus of course the qmgr's own checkpointing every so often... 
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| Andyh |
| Posted: Tue May 06, 2014 11:20 am Post subject: |
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Master
Joined: 29 Jul 2010
Posts: 239
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Non persistent messages are not written to the log, even if those messages are put within syncpoint.
Changes to MQ object attributes, including the creation and deletion of dynamic queues are logged.
Periodic checkpoints are taken which also result in log records being written, the frequency of checkpoints is based upon a number of factors, including the volume of data written to the logs, the volume of MQOPEN/MQCLOSE activity, and elapsed time since the last checkpoint.
One 'simple' way to see what's being written is to format the logs with the dmpmqlog command when the queue manager is not running. By default the dmpmqlog command will only dump the log records since the last checkpoint (typically only the checkpoint itself if the queue manager was shutdown normally), but if you include the -b option you'll typically get an idea of the recent activity against the recovery log. |
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