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| Roger |
 Posted: Wed May 26, 2010 4:11 am Post subject: can a clustered qmgr send multiple copies of a message? |
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Novice
Joined: 28 Jun 2001
Posts: 13
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| fatherjack |
| Posted: Wed May 26, 2010 4:21 am Post subject: Re: can a clustered qmgr send multiple copies of a message? |
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Knight
Joined: 14 Apr 2010
Posts: 522
Location: Craggy Island
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Nope. I think you're mis-reading this. Copies of messages are not sent to multiple queue managers in the cluster. Messages will be sent, in the scenario described in your link, to either one or the other of the two clustered queues with the same name. Which particular queue any message goes to will depend on a number of factors including availability of the queue manager and a bunch of MQ queue manager and queue attributes.
Read the MQ clustering documentation for more detail
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| Vitor |
| Posted: Wed May 26, 2010 4:28 am Post subject: Re: can a clustered qmgr send multiple copies of a message? |
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Grand High Poobah
Joined: 11 Nov 2005
Posts: 26093
Location: Texas, USA
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| Roger wrote: |
| which suggests a single clustered qmgr can send copies of a message to clustered queues of the same name |
I don't see anything in that link which says that copies of a message are being sent. It does indeed say:
| Quote: |
| The cluster to which this queue manager belongs causes messages to be distributed to all other queue managers in the cluster which have queue Q1 defined |
but I take that to mean that messages are distributed as per the normal WMQ function, i.e. the message load is distributed via the workload parameters across all the eligible targets. Not that the messages are evenly distributed across the cluster.
Likewise the comment:
| Quote: |
| messages are delivered to the other available application servers, until the WebSphere MQ server is back online, when messages are processed as expected |
should be read carefully, and in conjuction with the many discussions on this forum regarding WMQ clusters & their use in availability solutions.
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| mvic |
| Posted: Wed May 26, 2010 5:29 am Post subject: Re: can a clustered qmgr send multiple copies of a message? |
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Jedi
Joined: 09 Mar 2004
Posts: 2080
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| Roger wrote: |
| Has anyone achieved this configuration? |
It looks like you need publish/subscribe behaviour, so the best thing would be to use the publish/subscribe features of MQ. |
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| Roger |
| Posted: Wed May 26, 2010 5:30 am Post subject: |
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Novice
Joined: 28 Jun 2001
Posts: 13
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| Thanks for the responses - it must be my interpretation of the example figure and reading of the article. |
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| bruce2359 |
| Posted: Wed May 26, 2010 5:57 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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In the doc, pay attention to how workload in a cluster is managed - meaning: how is the next instance of the cluster queue selected.
At its simplist, at MQOPEN, the next instance of a clusterd queue is selected round-robin. But there are variations.
WMQ offers a cluster workload exit where you can fine-tune. V7 offers ranking and priority of queues and channels for further fine-tuning.
But in no case does WMQ replicate a message. Many admins new to WMQ incorrectly believe that messages flow from from the originating qmgr through a full-repository, and then to the destination qmgr and queue. This is not the case. All channels are point-to-point. Clustering software will dynamically create a point-to-point cluster-sender channel (if one does not yet exist) from the originating qmgr to the destination qmgr.
This post is in no way comprehensive. As advised in a prior post, you need to read and understand the WMQ Queue Manager Clusters manual.
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| Vitor |
| Posted: Wed May 26, 2010 6:41 am Post subject: |
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Grand High Poobah
Joined: 11 Nov 2005
Posts: 26093
Location: Texas, USA
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| bruce2359 wrote: |
| WMQ offers a cluster workload exit where you can fine-tune. V7 offers ranking and priority of queues and channels for further fine-tuning. |
So does v6. The OP might have that (but if so will obviously be thinking about upgrade schedules).
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| shashivarungupta |
| Posted: Tue Jun 15, 2010 6:01 am Post subject: |
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Grand Master
Joined: 24 Feb 2009
Posts: 1343
Location: Floating in space on a round rock.
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| Roger wrote: |
| .. it must be my interpretation of the example figure and reading of the article. |
Yup .
you can look into that article at 'Recovery Scenario' where at the 1st point they have mentioned 'what if one queue manager fails'.
"Failure of a queue manager on the same host as a WebSphere application server (for example, failure of QM2 on host S2). In this case messages are delivered to the other available application servers, until the WebSphere MQ server is back online, when messages are processed as expected"
Which says all.. that Round Robin / Workload balancing is happening in MQ Cluster.. rather then multiple copies of the messages are sent within the mq cluster.
THanks.
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