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MQSeries.net Forum Index » General IBM MQ Support » Circular logging

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Gideon
PostPosted: Wed Oct 23, 2013 1:24 pm    Post subject: Circular logging Reply with quote

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Joined: 18 Aug 2009
Posts: 403

If I use the WMQ defaults, including circular logging, what is the max the logs can grow.


How can I determine this on my machine
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bruce2359
PostPosted: Wed Oct 23, 2013 1:38 pm    Post subject: Re: Circular logging Reply with quote

Poobah

Joined: 05 Jan 2008
Posts: 9469
Location: US: west coast, almost. Otherwise, enroute.

Gideon wrote:
If I use the WMQ defaults, including circular logging, what is the max the logs can grow.


How can I determine this on my machine

What are the defaults? Did you search google for 'what are the queue manager log defaults'?
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exerk
PostPosted: Wed Oct 23, 2013 11:11 pm    Post subject: Re: Circular logging Reply with quote

Jedi Council

Joined: 02 Nov 2006
Posts: 6339

Gideon wrote:
If I use the WMQ defaults, including circular logging, what is the max the logs can grow.

How can I determine this on my machine

Look in the qm.ini file for the queue manager (once it's been created) or Windows registry (depending on WMQ version), or better still, the Info Centre for the version you're using, which will give you the information per platform.
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bruce2359
PostPosted: Thu Oct 24, 2013 6:05 am    Post subject: Reply with quote

Poobah

Joined: 05 Jan 2008
Posts: 9469
Location: US: west coast, almost. Otherwise, enroute.

Look also in the mqs.ini file in the filesystem. It determines the 'defaults' for qmgrs created in this o/s image or instance.
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exerk
PostPosted: Thu Oct 24, 2013 6:26 am    Post subject: Reply with quote

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Joined: 02 Nov 2006
Posts: 6339

bruce2359 wrote:
Look also in the mqs.ini file in the filesystem. It determines the 'defaults' for qmgrs created in this o/s image or instance.

Bruce, below is an mqs.ini file from a WMQ V7.5.0.2 installation:

Code:
#********************************************************************#
#*                                                                  *#
#* <N_OCO_COPYRIGHT>                                                *#
#* Licensed Materials - Property of IBM                             *#
#*                                                                  *#
#* 63H9336                                                          *#
#* (C) Copyright IBM Corporation 2011                               *#
#*                                                                  *#
#* <NOC_COPYRIGHT>                                                  *#
#*                                                                  *#
#********************************************************************#
#***********************************************************************#
#* Module Name: mqs.ini                                                *#
#* Type       : WebSphere MQ Machine-wide Configuration File           *#
#* Function   : Define WebSphere MQ resources for an entire machine    *#
#*                                                                     *#
#***********************************************************************#
#* Notes      :                                                        *#
#* 1) This is the installation time default configuration              *#
#*                                                                     *#
#***********************************************************************#
AllQueueManagers:
   #********************************************************************#
   #* The path to the qmgrs directory, below which queue manager data  *#
   #* is stored                                                        *#
   #********************************************************************#
   DefaultPrefix=C:\IBM\WebSphereMQ\V750

LogDefaults:
   LogDefaultPath=C:\IBM\WebSphereMQ\V750\log
QueueManager:
   Name=TEST01
   Prefix=C:\IBM\WebSphereMQ\V750
   Directory=TEST01
   InstallationName=InstA
QueueManager:
   Name=TEST02
   Prefix=C:\IBM\WebSphereMQ\V750
   Directory=TEST02
   InstallationName=InstA


Also, I looked in the registry and didn't see any 'defaults' listed in there so not sure where (on Windows at least) that information is stored. Sorry, don't have access to a UNIX system to look at the moment
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JosephGramig
PostPosted: Thu Oct 24, 2013 6:52 am    Post subject: Reply with quote

Grand Master

Joined: 09 Feb 2006
Posts: 1244
Location: Gold Coast of Florida, USA

Here is an example with more attributes specified.

When I don't have any information about the Qmgr I'm going to create, I make LogFilePages=16384 and always make LogBufferPages=4096.

I wonder if we can add Channel defaults or TCP defaults...

Maybe even add other default overrides:
Like DEFBIND(NOTFIXED) for all queues.
Like SSLCIPH(RC4_SHA_US) for all channels (to prevent accidental unprotected channel creation).
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bruce2359
PostPosted: Thu Oct 24, 2013 7:18 am    Post subject: Reply with quote

Poobah

Joined: 05 Jan 2008
Posts: 9469
Location: US: west coast, almost. Otherwise, enroute.

http://pic.dhe.ibm.com/infocenter/wmqv7/v7r1/index.jsp?topic=%2Fcom.ibm.mq.doc%2Ffa15650_.htm
Crtmqm doc documents the IBM-provided system defaults. These defaults will be used if not overridden in crtmqm command parameters.

If IBM-provided defaults are specified (overridden) in mqs.ini, then these mqs.ini values will be used for the next qmgr created - unless these are overridden in crtmqm command parms.
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krypton
PostPosted: Thu Oct 24, 2013 4:49 pm    Post subject: Long running transactions and RESOURCE problem. Reply with quote

Disciple

Joined: 14 Mar 2010
Posts: 186

I was Reading the manuals on Circular logging and I checked that although the space can be reclaimed, but there are scenarios when a Long Running Transaction can cause the logs to fail and results in error MQRC_RESOURCE_PROBLEM.

I am just wondering how come a single transaction can be so long that it fills up the few hundred MBs worth of logs.
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exerk
PostPosted: Fri Oct 25, 2013 2:02 am    Post subject: Re: Long running transactions and RESOURCE problem. Reply with quote

Jedi Council

Joined: 02 Nov 2006
Posts: 6339

krypton wrote:
...I am just wondering how come a single transaction can be so long that it fills up the few hundred MBs worth of logs.

Because some developer thinks it's a great idea to get message after message, all in the same UoW, and not commit until they get MQRC 2033. That might work for a small number of messages but is a disaster when there's zillions of messages.
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PeterPotkay
PostPosted: Fri Oct 25, 2013 4:59 am    Post subject: Reply with quote

Poobah

Joined: 15 May 2001
Posts: 7722

And its not only the number of messages that the misbehaving app deals with. If the bad app simply puts or gets one message under synpoint and then does not commit or rollback, and instead sits there for hours and days and weeks, while the QM is dealing with other applications that are causing the logs to be used, eventually that one uncommitted message from that one app will cause the logs to be full.

In the interest of the greater good, the QM then rolls back that one message whether the offending app likes it or not to release the checkpoint in the log.

If you have very small logs you are more likely to hit this scenario. Disk space is cheap. Your time is not. Make the MQ logs much, much bigger than the defaults when creating any QM other than a throwaway test QM.

But no matter how big you make them, if you have an app that never commits, you will get full logs and the message(s) will be rolled back for that uncomitted transaction.
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Vitor
PostPosted: Fri Oct 25, 2013 5:00 am    Post subject: Re: Long running transactions and RESOURCE problem. Reply with quote

Grand High Poobah

Joined: 11 Nov 2005
Posts: 26093
Location: Texas, USA

exerk wrote:
krypton wrote:
...I am just wondering how come a single transaction can be so long that it fills up the few hundred MBs worth of logs.

Because some developer thinks it's a great idea to get message after message, all in the same UoW, and not commit until they get MQRC 2033. That might work for a small number of messages but is a disaster when there's zillions of messages.


Or you're reading a file, putting the results of each record being processed into a queue and only commit when you hit end of file. Works fine with small numbers of records per file, a production file with millions of records leads to the disaster my worthy associate mentions above.
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