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| sirbrian |
 Posted: Thu Apr 16, 2009 6:39 am Post subject: Log switching problems. |
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Newbie
Joined: 11 Jun 2007
Posts: 9
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Hi,
I have a version 5.3.14 (I know, quite out of date) queue manager.
The queue manager has linear logging with the following parameters.
LogPrimaryFiles=50
LogSecondaryFiles=13
LogFilePages=16384
LogType=LINEAR
LogBufferPages=0
LogWriteIntegrity=TripleWrite
I have checked the log file directory and it seems to me that the queue manager is rolling forward on to a new log awfully quickly. It is barely a couple of minutes between the log files filling up and a new one being created by the QM. We have a (possibly) related problem where response times to this server are spiking at the same time as the QM is creating a new log file.
My questions are
1) What is a "normal" period between logfiles switching? Currently a log file is being created every 3 to 6 minutes.
2) Does the queue manager suspend all other work whilst creating a new log file.
Also my error logs are being filled with AMQ7467 and AMQ7468 messages. They are rolling round every couple of hours. I assume this is related to the log switching of MQ. Is this normal? I haven't touched MQ for a while but I can't remember this happening on any previous MQ installations I've worked on. |
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| mqjeff |
| Posted: Thu Apr 16, 2009 6:43 am Post subject: |
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Grand Master
Joined: 25 Jun 2008
Posts: 17447
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New log files get created when the old ones are full. It's based entirely on transaction volume.
Yes, at some point, MQ started writing messages when it rolled log files, so that automated log file management tools would have things to work from. |
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| exerk |
| Posted: Thu Apr 16, 2009 6:48 am Post subject: |
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Jedi Council
Joined: 02 Nov 2006
Posts: 6339
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Seems that 'something' is generating a lot of logging activity. Has an application suddenly gone totally tonto? Has the usage of the queue manager changed, e.g. it is now handling 2 - 3 times the volume it used to?
The AMQ7467 and AMQ7468 messages will be occurring because of the check-pointing by the queue manager, as logs become redundant.
_________________
It's puzzling, I don't think I've ever seen anything quite like this before...and it's hard to soar like an eagle when you're surrounded by turkeys. |
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| sirbrian |
| Posted: Thu Apr 16, 2009 6:50 am Post subject: |
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Newbie
Joined: 11 Jun 2007
Posts: 9
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Thanks mqjeff.
I'm interested to know what other peoples opinions are on how often a queuemanager should create a new log file. I think that once every couple of minutes is too often and that maybe my log files need resizing.
Currently each log file is about 64mb and I am filling one every couple of minutes. If I were to recreate the queuemanager and increase the number of LogFilePages would this give me a performance improvement. |
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| mqjeff |
| Posted: Thu Apr 16, 2009 6:52 am Post subject: |
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Grand Master
Joined: 25 Jun 2008
Posts: 17447
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| sirbrian wrote: |
| If I were to recreate the queuemanager and increase the number of LogFilePages would this give me a performance improvement. |
Yes. |
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| Vitor |
| Posted: Thu Apr 16, 2009 7:03 am Post subject: |
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Grand High Poobah
Joined: 11 Nov 2005
Posts: 26093
Location: Texas, USA
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| sirbrian wrote: |
| I'm interested to know what other peoples opinions are on how often a queuemanager should create a new log file. |
Entirely dependant on how many applications are connected and how many transactional messages are in use.
_________________
Honesty is the best policy.
Insanity is the best defence. |
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| PeterPotkay |
| Posted: Thu Apr 16, 2009 7:34 am Post subject: |
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Poobah
Joined: 15 May 2001
Posts: 7722
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| sirbrian wrote: |
I'm interested to know what other peoples opinions are on how often a queuemanager should create a new log file.
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It should create them as often as it needs to, which might be once a minute, once a year, or somewhere in between.
LogBufferPages should be set to the max of 4096, unless you are running on a server with 32MB of memory.
_________________
Peter Potkay
Keep Calm and MQ On |
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| JosephGramig |
| Posted: Fri Apr 17, 2009 4:54 am Post subject: |
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Grand Master
Joined: 09 Feb 2006
Posts: 1244
Location: Gold Coast of Florida, USA
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| And it is safe to switch to LogWriteIntegrity=SingleWrite since you are LINEAR. |
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