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| How to auto-reset sequence number? (We have 200+ chls...) |
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| Mr Butcher |
 Posted: Thu Jan 13, 2011 6:50 am Post subject: |
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Padawan
Joined: 23 May 2005
Posts: 1716
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looks like our points of view are not that far away from each other .......... 
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| bruce2359 |
| Posted: Thu Jan 13, 2011 7:18 am Post subject: |
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Poobah
Joined: 05 Jan 2008
Posts: 9475
Location: US: west coast, almost. Otherwise, enroute.
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| Quote: |
| For receiver, it is more difficult. The sequence error will only show up if a message is received, and not when the channel becomes "running". |
Sequence wrap mismatch will first be discovered when the channels try to attach at qmgr restart.
Sequence wrap mismatch can also be detected when the next batch is about to be sent.
MCAs send messages in UofWs. (One exception: non-persistent messages on NPMSPEED(FAST) channels.)
Messages sent in UofWs that did not complete (commit) will be re-sent when the sequence numbers are reset, and the channels are restarted. No messages will be lost.
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| Mr Butcher |
| Posted: Thu Jan 13, 2011 11:55 pm Post subject: |
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Padawan
Joined: 23 May 2005
Posts: 1716
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| Code: |
| Sequence wrap mismatch will first be discovered when the channels try to attach at qmgr restart. |
"sequence number wrap" is something different (e.g. going from 999999999999 to 1) and that is matched between the MCAs at channel start time (AFAIK it must be the same)
if your intention was to talk about the "sequence number being out of sync between the MCSs" then ...
how do you do that for a receiver? you need the proper sender to start (and to send a message). IMHO the "out of sequence number error" does not show up on channel start. it shows up when the first message is transferred.
i agree with the other statements ... although they have not been part of the discussion.... ?!?
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| bruce2359 |
| Posted: Fri Jan 14, 2011 4:40 am Post subject: |
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Poobah
Joined: 05 Jan 2008
Posts: 9475
Location: US: west coast, almost. Otherwise, enroute.
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From WMQ Intercommunications
Channel message sequence numbering
The channel uses sequence numbers to assure that messages are delivered, delivered without duplication, and stored in the same order as they were taken from the transmission queue. The sequence number is generated at the sending end of the channel and is incremented by one before being used, which means that the current sequence number is the number of the last message sent. This information can be displayed using DISPLAY CHSTATUS (see WebSphere MQ Script (MQSC) Command Reference ). The sequence number and an identifier called the LUWID are stored in persistent storage for the last message transferred in a batch. These values are used during channel start-up to ensure that both ends of the link agree on which messages have been transferred successfully.
From WMQ MQSC:
CURSEQNO
For a sending channel, this is the message sequence number of the last
message sent. It is updated as each message is sent, and when the channel becomes in doubt it is the message sequence number of the last message in the in-doubt batch.
For a saved channel instance, this parameter has meaningful information only if the channel instance is in doubt. However, the parameter value is still returned when requested, even if the channel instance is not in doubt.
For a receiving channel, it is the message sequence number of the last message that was received. It is updated as each message is received.
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I like deadlines. I like to wave as they pass by.
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Lex Orandi, Lex Credendi, Lex Vivendi. As we Worship, So we Believe, So we Live. |
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| Mr Butcher |
| Posted: Fri Jan 14, 2011 5:35 am Post subject: |
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Padawan
Joined: 23 May 2005
Posts: 1716
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yes, maybe thats what the manual reads. but my experience differs, and i tried it a few minutes ago to be sure and this is how it works for MQV6 on z/OS
started sender, send messages, worked fine
stopped sender
purged receiver channel
recreated receiver channel
started sender channel -> channel is running. no error messages
sent 1 message - got sequence error
| Quote: |
CSQX526E CSQ1 CSQXRCTL Message sequence error for channel
CSQ1.TO.CSQ2.TCP, sent=86 expected=1 |
same happenes with receiver on distributed (sender still on z/OS)
i dont think its a mqv6 / mqv7 issue as almost the same is written in the intercommunication manuals. i dont know if this is the same on sender and receiver on distributed, someone may try. to be honest - i dont care  . IMHO you get sequence errors when messages travel. not when channel start (without messages being transfered). maybe thats something IBM implied when they wrote that sentence.
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| fjb_saper |
| Posted: Fri Jan 14, 2011 6:06 am Post subject: |
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Grand High Poobah
Joined: 18 Nov 2003
Posts: 20763
Location: LI,NY
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If you are able to plan your qmgr rebuild, stop all receiving chls (script)
display the channel status (saved) (script) and make sure that you request the sequence number there. Then shutdown the qmgr and rebuild...
This would then be your basis to build the sequence number for the new qmgr.
Have fun 
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