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| aaryan |
 Posted: Tue Aug 25, 2009 3:35 am Post subject: Lost messages in DQM |
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Newbie
Joined: 25 Aug 2009
Posts: 6
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Hi,
I am new to DQM. Can anyone suggest me on following topics:
1. What happens to messages sent when the target QM is stopping?
2. How can we make sure that none of the messages are lost during transit?
3. Is there any way to retreive lost message?
thanks in advance........ |
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| Mr Butcher |
| Posted: Tue Aug 25, 2009 4:24 am Post subject: |
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Padawan
Joined: 23 May 2005
Posts: 1716
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1. messages will stay in the xmitq on the sending queuemanager when target queuemanager is down
2. MQ takes care of this. There is nothing you must do in addition to that. if you do not want to lose non persistent messages make sure your channels are set to NPMSPEED(NORMAL). Using NPMSPEED(FAST) non persistent messages may get lost (but then this is because MQ is allowed to do so by configuration).
3. no. some third party messages may be able to recover from linear logs. but - again - why do you expect messages to get lost? Trust MQ.
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Regards, Butcher |
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| sumit |
| Posted: Tue Aug 25, 2009 4:34 am Post subject: |
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Partisan
Joined: 19 Jan 2006
Posts: 398
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| Mr Butcher wrote: |
| 1. messages will stay in the xmitq on the sending queuemanager when target queuemanager is down |
and may be in uncommitted state. You need to reset the channel to retrieve the messages.
Go through MQ intercommunication manual for better understanding.
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Regards
Sumit |
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| Mr Butcher |
| Posted: Tue Aug 25, 2009 4:41 am Post subject: |
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Padawan
Joined: 23 May 2005
Posts: 1716
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there are even more things that can happen. but as he seems to be at a very basic MQ knowledge level i tried not to confuse with all details when being asked for basics.
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Regards, Butcher |
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| aaryan |
| Posted: Tue Aug 25, 2009 4:46 am Post subject: RE: Lost messages in DQM |
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Newbie
Joined: 25 Aug 2009
Posts: 6
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Hi,
Thanks for the quick reply.........
Actually we are getting a scenario where we are unable to locate the lost message. If we send message when target QM is up but before it being received, the target QM gets down and message is not in xmit.
1. Is there a way that this doesn't happen?
2. And if it happens, where can we find the message?
3. If again the target QM is down and we have set the channel to NORMAL speed then, as you said the messages are not lost, then where do they go if failed to reach target QM?
We are using MQ for Windows ver 6.0. |
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| Mr Butcher |
| Posted: Tue Aug 25, 2009 5:21 am Post subject: |
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Padawan
Joined: 23 May 2005
Posts: 1716
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iif message is not in the xmitq, and the channel is not indoubt, and you are not using npmspeed fast, then the messages have been send to and received by the target queuemanager. maybe they have not been processed by the receiving application because the queuemanager was in shutdown.
assuming the message was persistent then the message was stored in the queue on the target queuemanager and is availalbe for processing after the queuemanager is restarted.
assuming the message was non persistent, then it is discarded during queuemanager restart. this may look to you like a "lost" message, but this is how MQ treats non persistent messages. There is a NPMCLASS attribute of a queue you can use to make MQ "try" to keep non persistent messages during restart, but this is not for sure.
so, if your messages are persistent, nothing should get lost, even during qmgr shutdown or failure. your messages either reached the target queuemanager, or sit in the local XMITQ.
and - from my personal experience - 50% of all "lost" messages have never been put!
i hope you are not using MQ 6.0.0.0 but installed the most recent fix pack.
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Regards, Butcher |
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| bruce2359 |
| Posted: Tue Aug 25, 2009 5:37 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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Begin your problem-determination by asking the app developers if they are creating non-persistent messages. No matter whether they tell you persistent or non-persistent, briefly stop the sender-end channel and look into the xmit queue to verify what the app developers tell you.
If the messages are non-persistent on the sender end, they will be non-persistent when they arrive on the receiver-end qmgr.
During shutdown of the receiving end qmgr, messages in transit will be put to destination queues; but at restart non-persistent messages are discarded. This behavior is normal and well-documented. Messages that were in the xmit queue awaiting transmission will remain in the xmit queue until the qmgr starts and the channel is started.
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I like deadlines. I like to wave as they pass by.
ב''ה
Lex Orandi, Lex Credendi, Lex Vivendi. As we Worship, So we Believe, So we Live. |
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| sumit |
| Posted: Tue Aug 25, 2009 7:42 am Post subject: Re: RE: Lost messages in DQM |
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Partisan
Joined: 19 Jan 2006
Posts: 398
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| aaryan wrote: |
| 2. And if it happens, where can we find the message? |
What are the checks that you performed while looking for the messages? Are you sure the messages were not delivered to target q on target qmgr just before it went down?
Try out what Mr Butcher and bruce2359 has pointed here.
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Regards
Sumit |
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| bruce2359 |
| Posted: Tue Aug 25, 2009 8:04 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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| Quote: |
| where can we find the message? |
Some assumptions:
1. the application created a message, and
2. it was put to the xmit queue
The message may be in the transmission queue waiting to be sent.
Or having been transmitted across the network, it may be in the destination queue.
Or having been transmitted across the network), or it may be in a dead-letter queue.
_________________
I like deadlines. I like to wave as they pass by.
ב''ה
Lex Orandi, Lex Credendi, Lex Vivendi. As we Worship, So we Believe, So we Live. |
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| aaryan |
| Posted: Wed Aug 26, 2009 12:38 am Post subject: RE: Lost messages in DQM |
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Newbie
Joined: 25 Aug 2009
Posts: 6
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Thanks all for your replies...........
I think i have got my query resolved..........
Moving forward,
1. I want to know what is the significance of NPMSPEED, as far as i understand, if we use NORMAL then the source QM doesn't checks for the target QM's status............and vise versa, am i right in my undserstanding?
2. And what about NPMCLASS parameter? |
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| Mr Butcher |
| Posted: Wed Aug 26, 2009 1:19 am Post subject: |
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Padawan
Joined: 23 May 2005
Posts: 1716
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this is very well documented. from your question i assume, you did not read the manual. go and read, then return with what you did not understand.
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Regards, Butcher |
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| aaryan |
| Posted: Mon Aug 31, 2009 4:56 am Post subject: RE: Lost messages in DQM |
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Newbie
Joined: 25 Aug 2009
Posts: 6
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Hi.............
We am again facing the lost messages scenario.
What we are doing is...........we are using DQM with WBIMB..........we are trying to send messages from one flow to enother flow which is on different AIX box.......and one message is gettting lost sometimes when the target QM is shutting down..........the error WBIMB throws if RMLoadWorker not found..........is this error coming due to internal exception of broker or this is related to MQ?? Because RM problems are normally due to message Set error but here this problem start coming only after we implimented DQM.........
Can anyone suggest........... |
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| exerk |
| Posted: Mon Aug 31, 2009 5:04 am Post subject: Re: RE: Lost messages in DQM |
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Jedi Council
Joined: 02 Nov 2006
Posts: 6339
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| aaryan wrote: |
Hi.............
We am again facing the lost messages scenario. |
As has been stated, no, you are not. WMQ does not lose messages, but will discard them if so told.
| aaryan wrote: |
| ...and one message is getting lost sometimes when the target QM is shutting down... |
Only sometimes? Not every time? What's the pattern, if any? Are the queue manager and application state the same every time it happens?
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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.
Last edited by exerk on Mon Aug 31, 2009 5:25 am; edited 1 time in total |
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| Mr Butcher |
| Posted: Mon Aug 31, 2009 5:19 am Post subject: |
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Padawan
Joined: 23 May 2005
Posts: 1716
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you received quite a few tips and hints here to your initial question, did you follow them and checked what you should check? what were the results? and, most important, did you check the message persistence? what is it?
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Regards, Butcher |
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| aaryan |
| Posted: Mon Aug 31, 2009 8:19 pm Post subject: Re: RE: Lost messages in DQM |
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Newbie
Joined: 25 Aug 2009
Posts: 6
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| exerk wrote: |
| Only sometimes? Not every time? What's the pattern, if any? Are the queue manager and application state the same every time it happens? |
Yes only sometimes and that too only one message..........
there is no pattern and target QM gets down in immediate mode...........WBIMB i.e. our application is up at that time and exception is raised by WBIMB.........
| Mr Butcher wrote: |
| you received quite a few tips and hints here to your initial question, did you follow them and checked what you should check? what were the results? and, most important, did you check the message persistence? what is it? |
Yes we followed the steps but we kept the transmission queue and remote queue as non-persistence but messages are kept persistence.......does this make any effect?? |
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