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| channels in doubt state. 3 related questions |
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| pcrparimi |
 Posted: Wed Jul 17, 2002 5:43 am Post subject: channels in doubt state. 3 related questions |
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Apprentice
Joined: 09 Oct 2001
Posts: 43
Location: NY
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1). When do channels go to doubt status? Is it only because of Network problems? Many times I observed Sender channel in running state where as receiver channel in Inactive state, and no message being transmitted across even though there were some messages in the transmission queue associated with the sender channel.
2). Is there a chance of message duplication (delivering more than once) between two MQ Servers, because of channel is resolved with backout.
When should I use back out/commit for resolving.
3). When does Backout count of a message increase? Is it only because of MQGET failure under syncpoint. Does the backout count of a message increase If I resolve the channel by backout.
Thanks,
Poorna. |
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| mrlinux |
| Posted: Wed Jul 17, 2002 5:49 am Post subject: |
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Grand Master
Joined: 14 Feb 2002
Posts: 1261
Location: Detroit,MI USA
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I can answer number one
1) The channel will go into doubt when the SEQUENCE number that sender
sends doesnt match what receiver channel is expecting. This can happen
if the channels are down and someone resets the RCVR channel without
resetting the sender, queue mgr crashes, I have also seen a problem with
OS390 where someone had reset a SYSTEM.DEF.RECEIVER.CHANNEL and
when the MF qmgr started up and refreshed the objects is would reset
all the rcvr channels whose definition was refreshed.
_________________
Jeff
IBM Certified Developer MQSeries
IBM Certified Specialist MQSeries
IBM Certified Solutions Expert MQSeries |
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| dgolding |
| Posted: Wed Jul 17, 2002 6:05 am Post subject: |
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Yatiri
Joined: 16 May 2001
Posts: 668
Location: Switzerland
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Hi,
1) IN-DOUBT is very common on a heavily-active channel. This basically means that the last batch of messages (by default 50 in a batch) has not been acknowledged by the receiving side, so the channel is IN-DOUBT until this happens. This can happen intermittently several times.
If the channel status is RUNNING, and is in-doubt, don't worry!
2) Theoretically no - it's up to you to use resolve commit (throw away messages in XMITQ) or backout (send them again). The latter potentially could introduce this risk. I've had to use resolve maybe twice. You need to look at what you have received and decide your action.
3) BACKOUT COUNT is from an application that has backed out a destructive GET. It (AFAIK) is not the same as a resolve channel backed out.
HTH |
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| nimconsult |
| Posted: Wed Jul 17, 2002 10:06 pm Post subject: |
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Master
Joined: 22 May 2002
Posts: 268
Location: NIMCONSULT - Belgium
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2) Resolving channels, when not done correctly, can lead to loss of message (you COMMIT the last transmission, but the receiver did not commit it) or duplication of message (you BACKOUT the last transmission, but the receiver already committed it). Manual resolution of in-doubt channels is exceptionnal; as stated in a previous post in-doubt situations are in general resolved automatically. For appropriate manual resolution procedure read the "MQ Series intercommunication" manual, there is a chapter on the subject.
_________________
Nicolas Maréchal
Senior Architect - Partner
NIMCONSULT Software Architecture Services (Belgium)
http://www.nimconsult.be |
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| mqonnet |
| Posted: Tue Jul 23, 2002 5:49 am Post subject: |
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Grand Master
Joined: 18 Feb 2002
Posts: 1114
Location: Boston, Ma, Usa.
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There are known problems on quite a few versions relating to this problem. Hence if you post the OS, Version of Mq, might help.
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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