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| angka |
 Posted: Mon Nov 26, 2007 5:48 am Post subject: Channel Sequence Number issue |
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Chevalier
Joined: 20 Sep 2005
Posts: 406
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Hi,
Qmgr A is connected to Qmgr B via Sender Receiver Channel. the Qmgr are in different server. Whenever Server B auto shut down for some unknown reason, the Sequence number will be different in the Sender and Receiver Channel. The Sender channel in Qmgr A keep retrying and will need user intervention. Is there a way to prevent this from happening?
If the Sender Channel Sequence number is 10 for eg. and receiver channel is 8 does that means 2 msg is not commited in the receiver side?
Will there be possible lost of messages?
Thanks |
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| Vitor |
| Posted: Mon Nov 26, 2007 6:12 am Post subject: Re: Channel Sequence Number issue |
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Grand High Poobah
Joined: 11 Nov 2005
Posts: 26093
Location: Texas, USA
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| angka wrote: |
| Server B auto shut down for some unknown reason.....Is there a way to prevent this from happening? |
You need to get this unknown reason known. Check the logs and investigate.
| angka wrote: |
Will there be possible lost of messages?
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Depending on what happened and how the channel numbers were resyncronised then yes.
You need to get to the root cause of the problem.
_________________
Honesty is the best policy.
Insanity is the best defence. |
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| angka |
| Posted: Mon Nov 26, 2007 7:03 pm Post subject: |
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Chevalier
Joined: 20 Sep 2005
Posts: 406
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Hi,
Think it is due to power failure and the server went down. If i jus reset the Sender Sequence number will there be lost? or shld i resolve and rollback? but both this will need administrator intervention. is there a way to handle this sequence number issue automatically?
Thanks |
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| Vitor |
| Posted: Tue Nov 27, 2007 2:42 am Post subject: |
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Grand High Poobah
Joined: 11 Nov 2005
Posts: 26093
Location: Texas, USA
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| angka wrote: |
| is there a way to handle this sequence number issue automatically? |
If the MCAs could handle the sequence number issue they would have. The point here is they can't, they're not sure of the correct position (hence the channel is "in doubt"!) so they require manual intervention to correct the position and prevent message loss. You should use the procedure to resolve the channel (AFAIK just resetting the channel is more likely to cause loss) once you've determined what the message position is.
If the root cause is a power failure why consider automation? If it happens so often manual resolution is a pain what you really need is a more reliable power supply!
_________________
Honesty is the best policy.
Insanity is the best defence. |
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| angka |
| Posted: Tue Nov 27, 2007 3:21 am Post subject: |
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Chevalier
Joined: 20 Sep 2005
Posts: 406
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Hi,
I believe when the power failure happened, the Channel is sending some messages. I have another sender receiver channel pair connecting to the server B it has no problem with the sequence number cos the channel is seldom used. But when power failure the sender did not receive the ack why the sequence number become different?
So u suggest resolved and back out?
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| Vitor |
| Posted: Tue Nov 27, 2007 3:24 am Post subject: |
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Grand High Poobah
Joined: 11 Nov 2005
Posts: 26093
Location: Texas, USA
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| angka wrote: |
So u suggest resolved and back out?
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or resolved and commit, whichever is appropriate to your actual message position.
_________________
Honesty is the best policy.
Insanity is the best defence. |
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| angka |
| Posted: Tue Nov 27, 2007 3:30 am Post subject: |
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Chevalier
Joined: 20 Sep 2005
Posts: 406
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Hi,
Commiting => commiting the previous messages.. mayb the receiver has not received it. how can we find out??
Thanks.. |
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| Vitor |
| Posted: Tue Nov 27, 2007 3:33 am Post subject: |
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Grand High Poobah
Joined: 11 Nov 2005
Posts: 26093
Location: Texas, USA
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| angka wrote: |
how can we find out??
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You need to investigate in the source and target systems. If it could be determined from the information availible to MQ, the MCAs wouldn't be asking you the question.
_________________
Honesty is the best policy.
Insanity is the best defence. |
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| angka |
| Posted: Tue Nov 27, 2007 3:41 am Post subject: |
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Chevalier
Joined: 20 Sep 2005
Posts: 406
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Hi,
You mean verifying with the Receiver end whether they have received the messages? but the problem is alot of messages are piled up in the transmission queue and eg. 2 of the messages are in doubt, we will not be able to see those messages without rolling back so how can we verify?
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| jefflowrey |
| Posted: Tue Nov 27, 2007 3:47 am Post subject: |
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Grand Poobah
Joined: 16 Oct 2002
Posts: 19981
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If you have no way of determining what messages were sent, and determining what messages were received - outside of MQ - then you have no way of deciding properly whether to commit or rollback.
If this is true, then your business applications are not properly logging necessary business auditing data.
If this is true, then take your best guess, and when someone complains that "MQ lost messages", ask them how they know?
_________________
I am *not* the model of the modern major general. |
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| angka |
| Posted: Tue Nov 27, 2007 3:52 am Post subject: |
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Chevalier
Joined: 20 Sep 2005
Posts: 406
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Hi,
Ya on the sender side there is Message Exit to log the outgoing messages but the receiver side have none. can i assume that if the receiver side sequence number is less than the sender side, i need to resolve and rollback the sender channel?
Btw which is done first writing to local queue or adding the sequence number in the receiver side?
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| Vitor |
| Posted: Tue Nov 27, 2007 4:00 am Post subject: |
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Grand High Poobah
Joined: 11 Nov 2005
Posts: 26093
Location: Texas, USA
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| angka wrote: |
| can i assume that if the receiver side sequence number is less than the sender side, i need to resolve and rollback the sender channel? |
You can assume that, but there's no guarantee that's the case. As has been said before, you need to look outside MQ to determine what's actually happened. The MQ information is unreliable which is why the MCAs have flagged the in doubt status!
| angka wrote: |
Btw which is done first writing to local queue or adding the sequence number in the receiver side?
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Raise a PMR and ask. Only IBM would know for certain, and if it's the same sequence in all situations.
I don't think the knowledge would help you in this particular situation though.
_________________
Honesty is the best policy.
Insanity is the best defence. |
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| EddieA |
| Posted: Tue Nov 27, 2007 9:47 am Post subject: |
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Jedi
Joined: 28 Jun 2001
Posts: 2453
Location: Los Angeles
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There is, or at least used to be, (I haven't checked), a section in the Intercommunication Guide that steps you through how to check if you need to Commit, or RollBack messages when the Channel goes InDoubt.
Unless you follow that, to the letter, you will either lose messages, or you will have duplicates.
Cheers,
_________________
Eddie Atherton
IBM Certified Solution Developer - WebSphere Message Broker V6.1
IBM Certified Solution Developer - WebSphere Message Broker V7.0 |
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| PeterPotkay |
| Posted: Tue Nov 27, 2007 10:47 am Post subject: |
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Poobah
Joined: 15 May 2001
Posts: 7722
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| angka |
| Posted: Thu Nov 29, 2007 6:09 am Post subject: |
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Chevalier
Joined: 20 Sep 2005
Posts: 406
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Hi,
The link is very useful. Thanks. |
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