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| bruce2359 |
 Posted: Mon May 18, 2015 10:11 am Post subject: Does PR create CLUSSDR to the other FR? |
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Poobah
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This is from WebSphere MQ Queue Manager Clusters Version 7.0 SC34-6933-01:
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| Each queue manager that joins a cluster defines a cluster-sender (CLUSSDR) channel to one of the repositories. When it does this, it immediately learns which other queue managers in the cluster hold full repositories. From then on the queue manager can request information from any of the repositories. When the queue manager sends out any information about itself, for example when it creates a new queue definition, this information is sent to the chosen repository and also to one other repository (if there is one). |
I've highlighted the sentence I'm puzzled about. It is imprecise.
The highlighted bit suggests that the PR, after it publishes an object definition/update to its FR, will then connect to the other FR to notify it, too.
I seem to recall that a PR only publishes to its manually defined FR unless that FR becomes unavailable. If memory serves, when a PR publishes to its FR, that FR will republish to its partner FR.
Which is it?
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| mqjeff |
| Posted: Mon May 18, 2015 10:17 am Post subject: |
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Grand Master
Joined: 25 Jun 2008
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I have vague memories that the one manually defined FR connection sends info to create an auto-defined FR connection.
Easy enough to double-check. |
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| bruce2359 |
| Posted: Mon May 18, 2015 1:05 pm Post subject: |
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Poobah
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| mqjeff wrote: |
I have vague memories that the one manually defined FR connection sends info to create an auto-defined FR connection.
Easy enough to double-check. |
Yes, the manually defined FR will pass along to the other FR all of the objects it knows about.
My pondering is: at the creation of a new cluster object on a PR, does the PR also connect to the other FR to share the new definition; OR is it the manually defined FR that shares with the other FR? Have I misunderstood the extract from the manual?
I created a small cluster (FULL1, FULL2, PARTIAL3). PARTIAL3 uses FULL1 as its FR. All channels RUNNING. All qmgrs and channels display successfully. I create a new queue CLUSTERQ3 on PARTIAL3. Both FRs learn about it PDQ. However, NO new CLUSSDR from PARTIAL3 to FULL2 comes to life.
I end FULL1. On PARTIAL3, i terminate the CLUSSDR channel from PARTIAL3 to FULL1 (it was in rerty; I got bored waiting for retries to expire); and an automatically defined CLUSSDR from PARTIAL3 to FULL2 (the other FR) came to life - as expected.
I see no evidence that PARTIAL3 created a CLUSSDR channel to FULL2 until I caused FULL1 to fail.
It seems to me that ... also to one other repository (if there is one). is misleading in that a PR does NOT publish to the other FR directly - unless and until it becomes necessary.
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| PeterPotkay |
| Posted: Mon May 18, 2015 1:40 pm Post subject: |
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Poobah
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I went to a 7.5.0.4 Partial and did a channel status. No channels running to or from the Fulls.
I changed a clustered queue on the Partial that would cause an update to the cluster. Actually, all I did was add a period to the Description field of a clustered queue.
I did a Channel status again and there were cluster channels now running to both FRs, as well as from both FRs, all 4 channels with the exact same start date/time.
This post is related:
http://www.mqseries.net/phpBB2/viewtopic.php?t=65091&highlight=partial+full
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| bruce2359 |
| Posted: Mon May 18, 2015 1:48 pm Post subject: |
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Poobah
Joined: 05 Jan 2008
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Location: US: west coast, almost. Otherwise, enroute.
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| PeterPotkay wrote: |
I went to a 7.5.0.4 Partial and did a channel status. No channels running to or from the Fulls.
I changed a clustered queue on the Partial that would cause an update to the cluster. Actually, all I did was add a period to the Description field of a clustered queue.
I did a Channel status again and there were cluster channels now running to both FRs, as well as from both FRs, all 4 channels with the exact same start date/time.
This post is related:
http://www.mqseries.net/phpBB2/viewtopic.php?t=65091&highlight=partial+full |
I tested on 7.5.0.0, and see different results.
Did the PR in your test have a manually defined CLUSSDR channel to more than one FR?
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| PeterPotkay |
| Posted: Mon May 18, 2015 3:14 pm Post subject: |
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Poobah
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| bruce2359 wrote: |
Did the PR in your test have a manually defined CLUSSDR channel to more than one FR? |
Surely, you jest!
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Peter Potkay
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| bruce2359 |
| Posted: Mon May 18, 2015 5:20 pm Post subject: |
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Poobah
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| PeterPotkay wrote: |
| bruce2359 wrote: |
Did the PR in your test have a manually defined CLUSSDR channel to more than one FR? |
Surely, you jest! |
Sorry. i'll retest at v7.5.0.0 and v8.
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| bruce2359 |
| Posted: Mon May 18, 2015 5:57 pm Post subject: |
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Poobah
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| PeterPotkay wrote: |
| bruce2359 wrote: |
Did the PR in your test have a manually defined CLUSSDR channel to more than one FR? |
Surely, you jest! |
I let the cluster sit idle, and the CLUSSDR channel to the other FR disconnected.
I altered the clusterq definition on the PR; and, Voila!, a CLUSSDR appears from PR to the other FR.
...and I didn't think I'd learn anything today.
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| fjb_saper |
| Posted: Tue May 19, 2015 4:34 am Post subject: |
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Grand High Poobah
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Are you sure it's the PR sending to the second FR and not the second FR asking the PR for confirmation? What happens if you have more than 2 FR's?
Or if you stopped the sender channel from the 1st FR to the second FR?
What happens when you start the channel from the 1st FR to the second FR let's say one min after the update... 
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| mqjeff |
| Posted: Tue May 19, 2015 5:30 am Post subject: |
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Again, my vague memory was not that a manually defined connection to one FR would cause that FR to publish to the other FR(s)...
It was that the FR would communicate information to the PR to create an auto-defined channel to "at least" one other FR...
You wouldn't really want to risk having information only sent to one FR when things change. Too much chance for cluster fragmentation or otherwise out of date information, even if the FRs cross-communicate. |
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| bruce2359 |
| Posted: Tue May 19, 2015 5:46 am Post subject: |
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Poobah
Joined: 05 Jan 2008
Posts: 9396
Location: US: west coast, almost. Otherwise, enroute.
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| mqjeff wrote: |
| Again, my vague memory was not that a manually defined connection to one FR would cause that FR to publish to the other FR(s)... |
My recollection, too.
| mqjeff wrote: |
| It was that the FR would communicate information to the PR to create an auto-defined channel to "at least" one other FR... |
Same recollection for me.
What I didn't recall (caused by my misspent youth perhaps?) was that the PR would automatically create a CLUSSDR to the other FR. I've done a zillion DIS CHS(*) commands, and don't recall seeing the resulting channel from PR-to-other-FR. I guess I presumed that the PR-to-other-FR would be created in the manually defined PR-to-FR channel died, or the FR itself died.
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Lex Orandi, Lex Credendi, Lex Vivendi. As we Worship, So we Believe, So we Live. |
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| PeterPotkay |
| Posted: Tue May 19, 2015 4:30 pm Post subject: |
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Poobah
Joined: 15 May 2001
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There are 3 different types of Cluster Sender channels.
http://www-01.ibm.com/support/knowledgecenter/SSFKSJ_7.5.0/com.ibm.mq.ref.adm.doc/q086110_.htm
Issue DISPLAY CLUSQMGR and you can determine if the running channel from the PR to the FR is:
CLUSSDR - You only see this type the first time the PR talks to the FR, or after you issue REFRESH CLUSTER REPOS(YES). Its based on the manual definition you made of the CLUSSDR to the FR. That channel immediately shuts down and restarts as:
CLUSSDRA - A cluster sender from the PR to the FR that is based on the FR's CLUSRCVR
CLUSSDRB - A cluster sender based on the partner QM's CLUSRRCVR. You will see this type of channel from the PR to the other FR as long as you did not incorrectly also have a manually defined CLUSSDR to the 2nd FR.
bruce, are you chasing down a problem, or just curious how its working?
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Peter Potkay
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| bruce2359 |
| Posted: Tue May 19, 2015 9:30 pm Post subject: |
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Poobah
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Curious.
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| mqjeff |
| Posted: Wed May 20, 2015 4:53 am Post subject: |
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| PeterPotkay wrote: |
| You will see this type of channel from the PR to the other FR as long as you did not incorrectly also have a manually defined CLUSSDR to the 2nd FR. |
This is what I was not quite remembering. |
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| hughson |
| Posted: Wed May 20, 2015 11:58 pm Post subject: |
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When a PR repository makes contact with a FR for the first time, the FR sends it all the other FR CLUSRCVR definitions for that cluster. The PR then creates auto-CLUSSDRs for each of them. Thus a PR only NEEDs one manual CLUSSDR to bootstrap itself into the cluster.
If there are more than 2 FRs, it will have channels ready to use going to all of them, but for any one subscription it will only use two of them. To force it to always use a particular 2 of them, define a second manual CLUSSDR because it will use the manual ones in preference to the auto ones.
Cheers
Morag
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