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| MQ 6 Performance, lots of logs (gap between AMQ7467 and 8) |
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| DSPS |
 Posted: Thu Sep 11, 2008 1:20 am Post subject: MQ 6 Performance, lots of logs (gap between AMQ7467 and 8) |
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Apprentice
Joined: 11 Sep 2008
Posts: 44
Location: Southern England
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We have a number of performance challenges with a major application.
This application uses MQ 6 and WebSphere Application Server 6.0.2
Sometimes we find that things like rcdmqimg and mqllm.ksh don't behave as we would expect. Not only do we get left with large numbers of log files, but we also get a large span between numbers in the filenames for the log files that are mentioned in the AMQ7467 and AMQ7468.
These log files are 64MB in size.
My own feeling, borne by some of our performance testing is that the larger the number of log files and especially the larger the gap in the log file numbers between the AMQ7467 (The oldest log file required to start queue manager) and AMQ7468 (The oldest log file required to perform media recovery of queue ) the slower the queue manager goes.
Are there any MQ performance documents out there that might help to substantiate my own feeling and experience about this?
I have looked and searched, especially using Google and through some of the publications on the IBM redbooks site, a document on the BMC site and of course searched google desktop through my own extensive library of downloaded redbooks, no joy yet.
Thank you in advance. |
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| fjb_saper |
| Posted: Thu Sep 11, 2008 3:07 am Post subject: |
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Grand High Poobah
Joined: 18 Nov 2003
Posts: 20756
Location: LI,NY
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Don't know how you are treating your qmgr. But it is not a DB. Any persistent message that is not yet consumed will eat up space in your active logs.
Now to archive inactive logs you need to make sure they are inactive.
Running rcdmqimg with the right flag should also output the important log files (restart vs recovery). Do they match those you see in the logs? Is there a time log? What is the output of mqllm.ksh ?
We don't see any problems in this area and we run a combo of rcdmqimg / mqllm.ksh every hour.
Are you running the latest version of the support pack?
Are you using the temp directory when calling the archiving utility?
Enjoy 
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| DSPS |
| Posted: Thu Sep 11, 2008 3:29 am Post subject: |
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Apprentice
Joined: 11 Sep 2008
Posts: 44
Location: Southern England
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Yes, MQ isn't a database, but it is a participant in XA transactions where there is a database as well. We do a lot of these...Millions per day.
So, when you say that any persistent message that is not yet consumed will eat up log space. DEFPSIST is YES for these queues, and, if the messages are being consumed slowly, the build-up of data in these queues can be large (hundreds of thousands, possibly more) That could explain why the logs needed to recover have to be quite numerous. Is there much of an overhead for this? Is there a document / rebook that does highlight performance considerations for MQ in transaction processing environments?
We have taken the most recent version of the support PAC.
As for the temp directory question...
We run: -
mqllm.skh -q QMName -a ArchiveDirectory -d MQ_Home
and
rcdmqimg -l -m QMName -t "*" "*"
Is that what you were meaning? In some environments we only run this daily, in others (with higher load) we run hourly.
Peter |
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| fjb_saper |
| Posted: Thu Sep 11, 2008 3:40 am Post subject: |
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Grand High Poobah
Joined: 18 Nov 2003
Posts: 20756
Location: LI,NY
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You need to specify a temp directory when doing the mqllm.ksh call.
Check the mqllm.ksh script and the parm to the java call.
If the temp directory is not specified you risk inexpected behavior in very specific circumstances (rollover of AMQERR logs during the mqllm.ksh call).
I would expect the parm to be -d MQ_HOME to be your temp dir parm but better be safe and check as I don't have the system in front of me...
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