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| SAFraser |
 Posted: Fri Dec 14, 2007 8:14 am Post subject: More: MaxChannels and MaxActiveChannels |
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Shaman
Joined: 22 Oct 2003
Posts: 742
Location: Austin, Texas, USA
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Last month, I posted a question about maximum channel connections. http://www.mqseries.net/phpBB2/viewtopic.php?t=40559&highlight= There was confusion on the issue, even amongst our exalted grand masters.
I've had a chance to test a bit on my sandbox, and have come to these conclusions:
- MaxChannels limits all channels for which there is an entry in the channel status table.
- MaxActiveChannels limits only channels with a running status.
- In the absence of a MaxChannels entry, the default of 100 applies regardless of whether there is a MaxActiveChannels entry. i.e., MaxActiveChannels does not become the default for MaxChannels.
- Whatever is the most restrictive parameter will apply. i.e., if the limit for MaxChannels is reached but the MaxActiveChannels is not, the connection will be refused. If the limit for MaxActiveChannels is reached but the MaxChannels is not, the connection will be refused.
My takeaway from this is: Each parameter is still used, each operates independently, and each operates at the default of 100 unless set otherwise.
Tests were performed on MQ 6.0.2.2 on Solaris 9. If anyone wants me to post the details of what I tested, I'd be glad to.
Shirley |
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| jefflowrey |
| Posted: Fri Dec 14, 2007 8:43 am Post subject: |
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Grand Poobah
Joined: 16 Oct 2002
Posts: 19981
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I am *not* the model of the modern major general. |
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| fjb_saper |
| Posted: Fri Dec 14, 2007 9:01 am Post subject: |
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Grand High Poobah
Joined: 18 Nov 2003
Posts: 20756
Location: LI,NY
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Shirley
I believe we only set the MAXChannels=1000 in the .ini file (AIX 6.0.2.2) (IIRC) and the default of active channels is then the maxchls as we routinely go over 100 active channels
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MQ & Broker admin |
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| SAFraser |
| Posted: Fri Dec 14, 2007 9:57 am Post subject: |
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Shaman
Joined: 22 Oct 2003
Posts: 742
Location: Austin, Texas, USA
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I did experience the opposite effect - MaxActiveChannels as the only affirmatively set parameter - and it did not change the default value of the MaxChannels. I also tested a number of scenarios of affirmatively setting various combinations of the two parameters.
But I did not test the scenario you mention.... 
And, as I look back, I believe we ran for a long time with only MaxChannels set and far exceeded 100 active channel connections all the time.
I will confirm this in time on my little sandbox, but it does appear that the conclusion should be altered to add:
- In the absence of an affirmatively set MaxActiveChannels parameter, it will assume the value set for MaxChannels.
Does that capture it, do you think? I wonder what other scenarios I missed. This is why I'm an admin and not a test designer.
Shirley |
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| PeterPotkay |
| Posted: Fri Dec 14, 2007 10:05 am Post subject: |
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Poobah
Joined: 15 May 2001
Posts: 7722
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| SAFraser wrote: |
I will confirm this in time on my little sandbox, but it does appear that the conclusion should be altered to add:
- In the absence of an affirmatively set MaxActiveChannels parameter, it will assume the value set for MaxChannels.
Does that capture it, do you think? |
You got it Shirley. The SAG notes this exact scenario:
http://publib.boulder.ibm.com/infocenter/wmqv6/v6r0/topic/com.ibm.mq.amqzag.doc/fa12670_.htm
| Quote: |
MaxActiveChannels=MaxChannels_value
The maximum number of channels allowed to be active at any time. The default is the value specified on the MaxChannels attribute. |
_________________
Peter Potkay
Keep Calm and MQ On |
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| issac |
| Posted: Thu Oct 09, 2008 3:30 am Post subject: |
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Disciple
Joined: 02 Oct 2008
Posts: 158
Location: Shanghai
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| hah, i've found the info here so helpful. |
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| PeterPotkay |
| Posted: Thu Oct 09, 2008 5:37 am Post subject: |
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Poobah
Joined: 15 May 2001
Posts: 7722
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http://www-01.ibm.com/support/docview.wss?rs=171&uid=swg1IZ22725
| Quote: |
Error description
One section of the WebSphere MQ version 6 manual incorrectly
stated that the queue manager configuration MaxChannels
attribute in the CHANNELS stanza is ignored WebSphere MQ.
Local fix
Documentation amq521u is changed to document that the MaxChannel
MaxChannels attribute is not ignored.
Problem summary
****************************************************************
USERS AFFECTED:
Users who need to set their channels configuration to tune the
channel status table size
Platforms affected:
All Distributed (iSeries, all Unix and Windows)
****************************************************************
PROBLEM SUMMARY:
Topic "amq521u" in the WebSphere MQ manual contained an
incorrect statement regarding the MaxChannels configuration
setting.
The MaxChannels setting is not ignored and will still take
effect in WebSphere MQ 6 and above.
Problem conclusion
The WebSphere MQ manuals are amended to remove the incorrect
statement.
---------------------------------------------------------------
The fix is targeted for delivery in the following PTFs:
v6.0
Platform Fix Pack 6.0.2.5
-------- --------------------
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Peter Potkay
Keep Calm and MQ On |
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| JosephGramig |
| Posted: Thu Oct 09, 2008 6:55 am Post subject: |
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Grand Master
Joined: 09 Feb 2006
Posts: 1244
Location: Gold Coast of Florida, USA
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You know, I'm looking at a production QMGR and it has:
MaxChannels=5000
MaxActiveChannels=5000
And then I do:
echo 'DIS CHS(<MySVRCONN>)' |runmqsc <MyQMGR> |wc -l
and I get 12998. CHS is not returning connections? or what?
Also, when I count this way:
echo 'DIS CHS(*)' |runmqsc <MyQMGR>|grep CHANNEL|sort|uniq -c
And the total there equals the max (5000), I get the MaxChannels error.
BTW, for <MySVRCONN>, it now counts 2604 (and the number is not varying that much).
How bizarre, how bizarre... |
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