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| rsinha |
 Posted: Thu May 20, 2004 9:56 am Post subject: AMQ7469 Transactions rolled back to release log space |
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Apprentice
Joined: 29 Aug 2003
Posts: 42
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I'm trying to understand what causes this message, when there is plenty of disk space available, about 25 gig. Our end of MQ Server is receiving around 80 messages, average size of the message is 2MB, the BATCHSZ if the receive channel is set to 50. So that means the channel is trying to commit 100MB. We are using linear logs, primary 3 and secondary 2, and getting this error message - AMQ7469 Transactions rolled back to release log space
I don't understand why if we are using linear logs and have gigs of hard disk space, are we getting this problem. The size of each log file is about 16MB. Doesn't Q manager creates more log files with Linear log? Or does it only create the as many log files as are specified by the Primary, i.e. 3.
If thats the case then I can understand why we are getting this error, because channel is trying to commit 100MB data, where as with 3 primary files, it has only about 50 MB log space available.
Can someone please confirm my hypothesis? |
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| jefflowrey |
| Posted: Thu May 20, 2004 10:25 am Post subject: Re: AMQ7469 Transactions rolled back to release log space |
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Grand Poobah
Joined: 16 Oct 2002
Posts: 19981
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| rsinha wrote: |
So that means the channel is trying to commit 100MB. We are using linear logs, primary 3 and secondary 2, and getting this error message - AMQ7469 Transactions rolled back to release log space
The size of each log file is about 16MB. Doesn't Q manager creates more log files with Linear log? Or does it only create the as many log files as are specified by the Primary, i.e. 3.
If thats the case then I can understand why we are getting this error, because channel is trying to commit 100MB data, where as with 3 primary files, it has only about 50 MB log space available.
Can someone please confirm my hypothesis? |
Have you considered consulting the documentation to confirm your hypothesis?
3 Primary log files and 2 secondary log files means that MQ will use no more than 5 log files total. If each log file is 16MB in size, then 5*16 should just about cover your 100MB of data. If you don't have any other transaction space going on.
But when talking about channels, you have to consider the log file size on BOTH queue managers.
Regardless, 3 primary and 2 secondary is likely too few for your setup. Since you do have plenty of disk space, I would increase the number of both to something like 16. That should provide you reasonable space for a while without wasting too much.
Unless all that disk space is dedicated to your Queue Manager, in which case go ahead and configure it to the maximum number of files you can (I believe that it's 63 total and 61 primary).
But please take some time to read the relevant sections of the System Administration guide.
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I am *not* the model of the modern major general. |
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| mqonnet |
| Posted: Thu May 20, 2004 10:34 am Post subject: |
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Grand Master
Joined: 18 Feb 2002
Posts: 1114
Location: Boston, Ma, Usa.
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rsinha, the link below perfectly pin-points your question and answers it well, the last paragraph. Unfortunately i couldnt find similar wording in the latest manuals though. But as long as it is explained somwhere that should suffice.
http://www-1.ibm.com/support/docview.wss?uid=swg21029067
"Take a look at the MQSeries System Administration Manual Ch12
Recovery and Restart - Linear Logging (pg.173). Although you may have
any number of inactive log files there can only be a finite number of
active log files which is specified by the number of primary and
secondary logs. When, as in this case, there is a long running
transaction the logger cannot make a log file inactive and so will
resort to its secondary log file pool. If having used all the
secondary log files, the transaction is still not closed then the
logger will have to rollback the transaction to free up some active
log space. It is not related to the disk being full. You can see that
in the code you discuss which is not looking at how much disk space
is available but at the oldest active transaction id.
"
"Doesn't Q manager creates more log files with Linear log"
---Yes it does. And thats the whole point of linear logging. Of course constraints are that you have enough disk space to create as many log files.
"Regardless, 3 primary and 2 secondary is likely too few for your setup"
---Doesnt matter. Since linear logging would create as many as is required at run time.
Hope this helps.
Cheers
Kumar
_________________
IBM Certified WebSphere MQ V5.3 Developer
IBM Certified WebSphere MQ V5.3 Solution Designer
IBM Certified WebSphere MQ V5.3 System Administrator |
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| jefflowrey |
| Posted: Thu May 20, 2004 11:55 am Post subject: |
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Grand Poobah
Joined: 16 Oct 2002
Posts: 19981
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| mqonnet wrote: |
Although you may have
any number of inactive log files there can only be a finite number of
active log files which is specified by the number of primary and
secondary logs. "
"Regardless, 3 primary and 2 secondary is likely too few for your setup"
---Doesnt matter. Since linear logging would create as many as is required at run time.
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Kumar - the relevant point in that quote from the manual is the difference between active log files versus inactive log files.
Transactions cannot span over inactive log files.
So even with linear logging, the number of primary and secondary log files DOES matter - as you can't have transactions that cover more than the total space available in all logs.
So if I create a queue manager with 1 primary log file and one secondary log file, and the log file size is 16Mb, then I cannot send a message over a channel that is 33MB in size. Ever.
Nor can I send any combination of smaller messages where the total size of the messages in the channel batch is larger than 32MBs. So if I'm only sending messages that are 4 MB or smaller, I can set the channel batch size to 1 and never have problems moving messages over the channel.
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| mqonnet |
| Posted: Thu May 20, 2004 12:07 pm Post subject: |
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Grand Master
Joined: 18 Feb 2002
Posts: 1114
Location: Boston, Ma, Usa.
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Right.
I should have probably added transactionality to my previous comments. :)
Likewise you too missed it out.
"So if I create a queue manager with 1 primary log file and one secondary log file, and the log file size is 16Mb, then I cannot send a message over a channel that is 33MB in size. Ever.
"
---You can, if they are NOT in a uow.
As long as the messages are committed and they dont span over the active logs, one should be fine.
Cheers
Kumar
_________________
IBM Certified WebSphere MQ V5.3 Developer
IBM Certified WebSphere MQ V5.3 Solution Designer
IBM Certified WebSphere MQ V5.3 System Administrator |
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| jefflowrey |
| Posted: Thu May 20, 2004 12:35 pm Post subject: |
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Grand Poobah
Joined: 16 Oct 2002
Posts: 19981
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| mqonnet wrote: |
| jefflowrey wrote: |
| " I cannot send a message over a channel that is 33MB in size. Ever. " |
---You can, if they are NOT in a uow.
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How do I send a message over a channel that is not in a UOW? 
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| mqonnet |
| Posted: Thu May 20, 2004 1:11 pm Post subject: |
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Grand Master
Joined: 18 Feb 2002
Posts: 1114
Location: Boston, Ma, Usa.
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Ok, i overlooked the channel bit. :)
Cheers
Kumar
_________________
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IBM Certified WebSphere MQ V5.3 Solution Designer
IBM Certified WebSphere MQ V5.3 System Administrator |
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| PeterPotkay |
| Posted: Thu May 20, 2004 1:14 pm Post subject: |
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Poobah
Joined: 15 May 2001
Posts: 7722
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| Quote: |
How do I send a message over a channel that is not in a UOW?
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Channel speed is set to FAST, and you send a Non Persistent message.
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Peter Potkay
Keep Calm and MQ On |
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| JT |
| Posted: Thu May 20, 2004 1:21 pm Post subject: |
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Padawan
Joined: 27 Mar 2003
Posts: 1564
Location: Hartford, CT.
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| Quote: |
| How do I send a message over a channel that is not in a UOW? |
Technically, if that message were logical and segmented, it need not be in the same uow (just keeping you on your toes....you didn't say a physical message). |
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| mqonnet |
| Posted: Thu May 20, 2004 5:53 pm Post subject: |
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Grand Master
Joined: 18 Feb 2002
Posts: 1114
Location: Boston, Ma, Usa.
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I think we are discussing that is very much obvious and we all know what it is and how it works.
The discussion has been why the transaction rolled back. Of course these were persistent messages that were put in a UOW by the channel. So, lets just see if our posts helped resolve the original problem.
Just my 2cents. :)
Cheers
Kumar
_________________
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IBM Certified WebSphere MQ V5.3 Solution Designer
IBM Certified WebSphere MQ V5.3 System Administrator |
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