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| WBI_User21 |
 Posted: Fri Mar 05, 2010 12:56 pm Post subject: Max active channels. |
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Voyager
Joined: 12 Jun 2007
Posts: 98
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| Hello MQ Experts :. Due to growing use of MQ Estate in our enterprise , we started facing this problem in most of the queue managers : Max active channels reached . Increase the max channels value in the qm.ini file and restart queue manager .Now the big question is what should we set this value to , so that we need not restart any queue manager atleast for next 2 years .Our MQ Administrator proposed a number :2000 . But it is not really convincing to go with this number , unless we are aware of impact of this on the server . We are unable to simulate this as queue managers in test environments are hardly part of 10 or 15 queue manager cluster where as production environments a typical queue manager is part atleast 150 qms clusters. Can any one help me in understanding the impact on the server , when the load on server is peak and al 2000 channel utilized ? If you have such settings in your queue managers , please share your experience . Thanks in advance . Happy weekend |
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| Vitor |
| Posted: Fri Mar 05, 2010 1:22 pm Post subject: |
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Grand High Poobah
Joined: 11 Nov 2005
Posts: 26093
Location: Texas, USA
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Each connection uses resources, mostly memory. There is hence a finite limit on the number of connections you can have and a max limit on the queue manager prevents them running away and using all the available memory.
You need enough channels for all of the simultanious connections needed on each queue manager. AFAIK the footprint is fairly small (someone else will probably know how small) and I'd say 2000 was a good guesstimate and something a mid sized Unix box will handle.
I've seen it set to 5000 on a big 8-way with quite a lot of memory.
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| mvic |
| Posted: Fri Mar 05, 2010 1:43 pm Post subject: Re: Max active channels. |
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Jedi
Joined: 09 Mar 2004
Posts: 2080
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| WBI_User21 wrote: |
| Increase the ... value in the qm.ini file and restart queue manager |
This is OK if client apps were behaving OK, disconnecting in a timely way etc. Were they? Maybe they weren't...
If you have a lot of client programs there needs to be a balance between MaxActiveChannels and the OS keepalive interval. If client apps are not cleanly disconnecting, this can give growth in the active channel instances and you might need to tune the OS keepalive intervals to help cope.
Even if this doesn't affect you much now, it might do increasingly if, some months from now, a new client app suite is introduced that has these characteristics.
| WBI_User21 wrote: |
| Our MQ Administrator proposed a number :2000 . But it is not really convincing to go with this number , unless we are aware of impact of this on the server . |
It all depends - eg.
* system spec (RAM, CPU, I/O bandwidth)
* requirements today
* requirements next month, year etc.
I suggest to monitor over a few days the use of the system, observe trends, and take early action if you see certain limits will be hit. |
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| exerk |
| Posted: Fri Mar 05, 2010 1:47 pm Post subject: Re: Max active channels. |
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Jedi Council
Joined: 02 Nov 2006
Posts: 6339
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| WBI_User21 wrote: |
| ...Now the big question is what should we set this value to , so that we need not restart any queue manager atleast for next 2 years... |
No intention to apply maintenance then? Or upgrade if you're on < V7.0 ? 
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| WBI_User21 |
| Posted: Fri Mar 05, 2010 4:46 pm Post subject: |
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Voyager
Joined: 12 Jun 2007
Posts: 98
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@Vitor : thank you
@mvic thank you .. DISCINT is set 0 within mQ CHANNELS. There are no apps connecting to MQ through SVRCONN channel. There is plan tune to this parameter too. But it would trigger cluster updates within queue manager which seems be undersirable .
Yes we do have plans to upgrade to MQ v7.0  |
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| exerk |
| Posted: Fri Mar 05, 2010 4:57 pm Post subject: |
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Jedi Council
Joined: 02 Nov 2006
Posts: 6339
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There is much discussion on this board on the merits/demerits of setting DISCINT to 0 (zero) and the effect it has on channel recovery. It would be well worth your while spending time finding some of those posts, and maybe review your decision.
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It's puzzling, I don't think I've ever seen anything quite like this before...and it's hard to soar like an eagle when you're surrounded by turkeys. |
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| Vitor |
| Posted: Fri Mar 05, 2010 5:00 pm Post subject: |
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Grand High Poobah
Joined: 11 Nov 2005
Posts: 26093
Location: Texas, USA
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| WBI_User21 wrote: |
| Yes we do have plans to upgrade to MQ v7.0 |
The point my associate was making is that if you don't plan to restart any queue managers for 2 years, how will you do this upgrade?
This is  but that's an unrealistic goal. 2 whole years without a restart?
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| mvic |
| Posted: Fri Mar 05, 2010 5:05 pm Post subject: |
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Jedi
Joined: 09 Mar 2004
Posts: 2080
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| WBI_User21 wrote: |
| There are no apps connecting to MQ through SVRCONN channel. |
OK. That should make choosing a value for maxactivechannels much simpler.
| Quote: |
| There is plan tune to this parameter too. But it would trigger cluster updates within queue manager which seems be undersirable . |
What do you mean precisely by triggering cluster updates? I'm not sure what is undesirable about cluster updates.
exerk is right, check previous discussions about DISCINT 0.
But it is a valid setup to have DISCINT 0. So what drove your active channels through your limit? Unplanned / unsized deployments?
The choice of maxactivechannels is totally in the hands of you / your architects. I am unsure how much we can add from a public forum.
Kindest regards |
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| bruce2359 |
| Posted: Fri Mar 05, 2010 6:22 pm Post subject: |
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Poobah
Joined: 05 Jan 2008
Posts: 9472
Location: US: west coast, almost. Otherwise, enroute.
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If you are targeting no outages or config changes for two years, your developers, managers, clients and other interested parties, need to project as best they can the number of channels they expect to see at the 2yr mark.
There is likely some relationship between your business (retail, for example), anticipated growth (new stores), number of customers, historical growth, industry growth, qmgr replication (new qmgrs over time).
Then take that number (guess), round up to the nearest 100, then increase the result by some imaginary fudge-factor (to possibly compensate for under estimation). 50-100% fudge-factor has worked for me in the past.
Others will offer their SWAG equations, I'm sure.
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| fjb_saper |
| Posted: Fri Mar 05, 2010 9:16 pm Post subject: Re: Max active channels. |
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Grand High Poobah
Joined: 18 Nov 2003
Posts: 20756
Location: LI,NY
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| WBI_User21 wrote: |
| We are unable to simulate this as queue managers in test environments are hardly part of 10 or 15 queue manager cluster where as production environments a typical queue manager is part atleast 150 qms clusters. Can any one help me in understanding the impact on the server , when the load on server is peak and al 2000 channel utilized ? If you have such settings in your queue managers , please share your experience . Thanks in advance . Happy weekend |
It is not that you are unable to simulate, it is more that either you do not understand clusters or did not make the calculations.
Ok so you have 150 qmgrs in the cluster. Each qmgr will need the potential to run 150 channels + the number of FRs in your cluster(s).
This without taking into account any of the svrconn channels and other defined sdr / rcvr or svr/rqstr channels...
I believe the default to be 100 channels...(from memory) So yes you do need the channels stanza in the qm.ini to allow for enough channels to take care of your business. 2000 however seems a little bit excessive. You need to check out your needs do some computations and add at least 50% on top.
Have fun 
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| bruce2359 |
| Posted: Sat Mar 06, 2010 6:50 am Post subject: |
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Poobah
Joined: 05 Jan 2008
Posts: 9472
Location: US: west coast, almost. Otherwise, enroute.
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| Quote: |
| 2000 however seems a little bit excessive. |
Or not.
Without sufficient and accurate data do any prediction, you are left to do a SWAG or just pick a number from your wildest imagination. 5000 might get you 2 years. As explained in a prior post, the only downside to over-estimating and over-specifying max active channels is the potential use of resources (RAM and cpu). Buy more.
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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: Mon Mar 08, 2010 6:07 pm Post subject: |
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Poobah
Joined: 15 May 2001
Posts: 7722
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The bigger the cluster, the more QMs that you have the very rarely talk with every single QM in the cluster, but somethimes do, the more important it is NOT to have DISCINT = 0. Do you really need the channel from QM1 connecting to QM999 running forever if QM1 only needed to send something to QM999 once, in the year 2005?
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Peter Potkay
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| fjb_saper |
| Posted: Mon Mar 08, 2010 9:52 pm Post subject: |
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Grand High Poobah
Joined: 18 Nov 2003
Posts: 20756
Location: LI,NY
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| PeterPotkay wrote: |
| The bigger the cluster, the more QMs that you have the very rarely talk with every single QM in the cluster, but somethimes do, the more important it is NOT to have DISCINT = 0. Do you really need the channel from QM1 connecting to QM999 running forever if QM1 only needed to send something to QM999 once, in the year 2005? |
It also helps you to keep down the number of active channels.
However you should still set the max keeping in mind that in the worst case scenario each qmgr needs to talk to every qmgr in the cluster.
Have fun
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