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| MQ Clusters and HA |
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| mqnomad |
 Posted: Wed May 05, 2010 8:18 am Post subject: MQ Clusters and HA |
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Acolyte
Joined: 18 Mar 2010
Posts: 53
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OK, I have read the other comments that people that use QM clusters for HA are .... well, you know what you've said. So, I hear your.
I am looking at a very large customer who only sends non-persistent messages and since they have np msgs and save their definitions with the saveqmgr script, they're not too dependent on logs.
I am reading a white paper on Understanding HA with WMQ ...
http://www.ibm.com/developerworks/websphere/library/techarticles/0505_hiscock/0505_hiscock.html
on page 10 it states:
"... or for non-persistent messages (where an application is not relying on WebSphere MQ for assured delivery). For these situations, you can make a system highly available by using WebSphere MQ queue manager clustering only. This technology load balances messages and routes around failed servers. "
So if HA will mostly help if messages are logged and logs are linear ... in the case of queue managers with only non-persistent messages, what other HA solution would you recommend and why?
... I am too traumatized to dare say MQ clustering  |
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| bruce2359 |
| Posted: Wed May 05, 2010 8:39 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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You might want to think of HA as Hardware Availability. There are a few well-known vendors that offer hardware-level fail-over solutions.
MQ clustering is different. MQ clustering offers rudundant destination queues across multiple qmgrs in the cluster. WMQ clustering is not a fail-over solution.
For example, if application program A connects to qmgr Z, but the qmgr dies, or the hardware where qmgr Z runs dies, then there is no message, OR the message is now stranded on the dead qmgr A. Likewise, if A puts a message to a (clustered) destination queue on qmgr R, and qmgr R dies or the hardware dies, the message is now stranded on the dead qmgr.
This is where non-persistent vs. persistent messages arises. At restart, non-persistent messages are (usually) purged from queues, persistent messages are not. Thus, stranded messages are once again available for consumption.
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| mqnomad |
| Posted: Wed May 05, 2010 8:42 am Post subject: |
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Acolyte
Joined: 18 Mar 2010
Posts: 53
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Thanks bruce - but if all messages are non-persistent, they will be gone anyways - so what would the point of an HA hardware solution be for non-persistent messages.
Customer cannot afford pers. msgs due to performance - so the messages in the failed queue mgr will be lost anyways.
So for the case of only non-pers. messages, what the paper explains is that at least WMQ clusters would provide a degree of failover (meaning another queue mgr available, not message recovery) -
so in this customer's case, would QM clusters be justified? |
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| bruce2359 |
| Posted: Wed May 05, 2010 8:53 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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Yes, if the client wants to have multiple possible destination queues AND consuming applications, such that if one destination queue becomes unavailable, another can be the recipient of the next message.
_________________
I like deadlines. I like to wave as they pass by.
ב''ה
Lex Orandi, Lex Credendi, Lex Vivendi. As we Worship, So we Believe, So we Live. |
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| mvic |
| Posted: Wed May 05, 2010 12:33 pm Post subject: Re: MQ Clusters and HA |
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Jedi
Joined: 09 Mar 2004
Posts: 2080
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| mqnomad wrote: |
| So if HA will mostly help if messages are logged and logs are linear ... in the case of queue managers with only non-persistent messages, what other HA solution would you recommend and why? |
HA for non-persistent messages... is this the System Requirement you are evaluating?
Have you found the queue attribute NPMCLASS(HIGH) ? It causes a queue to offer a higher class of service to non-persistent messages. |
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| bruce2359 |
| Posted: Wed May 05, 2010 12:55 pm Post subject: |
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Poobah
Joined: 05 Jan 2008
Posts: 9469
Location: US: west coast, almost. Otherwise, enroute.
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| Quote: |
| Have you found the queue attribute NPMCLASS(HIGH) ? It causes a queue to offer a higher class of service to non-persistent messages. |
But, this attribute doesn't guarantee retention of non-persistent messages UNLESS the qmgr ends gracefully.
_________________
I like deadlines. I like to wave as they pass by.
ב''ה
Lex Orandi, Lex Credendi, Lex Vivendi. As we Worship, So we Believe, So we Live. |
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