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| Increase log file size |
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| dc01bb |
 Posted: Fri Jan 02, 2009 5:57 am Post subject: Increase log file size |
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Novice
Joined: 25 Oct 2001
Posts: 17
Location: Bruce Baxter
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We just got bit with our first (and certainly not last) poorly designed application that was batching up thousands of logical transactions into a single unit of work. They overran the log file space, got a 2003 return code and then cried that MQ Series was broken. After I set them straight, I began looking at ways to minimize the chances of this happening again.
For most of our application's the default circular log file sizings work just fine, but I was looking at the forums here the other night while rather bleary eyed and happened on a useful thread that discussed resizing the log files.
It mentioned a) log file counts can be modified and implemented across a restart, b) if you need to change the number of pages in the log file, while the recommendation is to re-create the queue manager, there is an unsupported procedure that seems to wok whereby you quiesce the queue manager orderly, create a new queue manager with the desired log parameters, and then overlay the contents of the <mqpath>/log directory fo the desired queue manager, and c) they gave some details on how the secondary log files get created and made reference to a sample program they used to put large messages for testing.
I can't recall the name of the sample/utility program they mentioned for testing, and neither have I been able to locate this thread. I was rather bleary eyed reading that thread, so it's possible that it wasn't even in the forums here. The utility took a message size and count as input and wrote test messages to a queue manager.
Help... Can anyone point me in the right direction.
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IBM Certified Specialist - MQSeries |
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| bruce2359 |
| Posted: Fri Jan 02, 2009 6:16 am Post subject: |
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Poobah
Joined: 05 Jan 2008
Posts: 9469
Location: US: west coast, almost. Otherwise, enroute.
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Ah, you've encountered the one potential and significant drawback of circular logs, namely: they are in a continuously re-used loop. Long-running UofWs can and will wrap all log segments.
If you never want to have this issue again, use linear logs.
Circular vs. Linear, and log sizing, are discussed in the WMQ System Administration manual.
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I like deadlines. I like to wave as they pass by.
ב''ה
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Last edited by bruce2359 on Fri Jan 02, 2009 6:43 am; edited 3 times in total |
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| dc01bb |
| Posted: Fri Jan 02, 2009 6:20 am Post subject: |
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Novice
Joined: 25 Oct 2001
Posts: 17
Location: Bruce Baxter
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FWIW, the utility that I read about and can't locate now was an amq prefixed program name. I've yet to find this utility name, and am going out to look in the samples directory...
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IBM Certified Specialist - MQSeries |
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| PeterPotkay |
| Posted: Fri Jan 02, 2009 12:12 pm Post subject: |
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Poobah
Joined: 15 May 2001
Posts: 7722
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Long running UOWs will eventually fill up all the disk space you have available for Linear Logs so Linear Logs are not a 100% guarantee against never seeing MQRC 2003.
If you are running with the log defaults I would definitly bump them up. As of MQ 6.0, you can create much much bigger logs and lots, lots more of them. You don't need to recreate your QM if you just want to up the number of circular logs.
Given x GB of space allocated for MQ logs (Circular or Linear) I prefer to have fewer, bigger logs.
Don't forget to max out the LogBuggerPages setting too. Any modern server can spare 16MB of memory to minimize logging I/O.
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Peter Potkay
Keep Calm and MQ On |
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| Cressida |
| Posted: Thu Aug 25, 2011 2:31 am Post subject: |
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Disciple
Joined: 13 Jul 2007
Posts: 157
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With upfront apology to the community for opening a few older posts re managing MQ Logs (changing attributes, circular vs linear, inability to do media recovery on circular logs, ...) ........., we at Cressida wanted to bring a new announcement to people's attention some:
For a long time we have been hearing and reading how the Distributed platforms WMQ administrators and systems staff have been looking for and wanting more built in WMQ Log Management functionality as found in the zOS WMQ environment. Well, we have done something about that !
Introduction of a new Log Manager component in ReQuest for WMQ Version 5.0:
• Log Manager introduces extensive functionality for manipulating and changing all WebSphere MQ queue manager attributes stored in .ini files and/or the Windows Registry. The list of features include the ability to switch between linear/circular logging and changing the size and attributes of the log files. If the changes made require that the queue manager is physically recreated, Log Manager ensures that all existing objects and messages are preserved during the process.
• Log Manager brings WMQ administrators the added built-in functionality to create archive copies (optionally compressed) of the active log files, regardless of whether the Queue Manager uses linear or circular logging. When using linear logging, log files that have been archived and are no longer needed for (WMQ) recovery, are automatically deleted from the active directory. When using circular logging, ReQuest’s Recover function can be used to recover from media failures.
I hope this helps to re-generate a few healthy discussions on the subject.
Thank you. |
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