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| lcw82 |
 Posted: Wed Feb 20, 2008 7:28 am Post subject: MSCS failover scenario |
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Newbie
Joined: 20 Feb 2008
Posts: 2
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Hi,
I am pretty new to clustering technology so would like to gather some advice here.
I am trying to cluster across MQ 3 nodes (Active-Active-Passive) using MSCS.
1. I heard about MQ manager clustering. Is it normally advisable to run MQ manager clustering on top of OS clustering?
2. Are there any load balancing with MSCS, or do I need to configure NLB or add an external load-balancer?
2. During failover, what kind of disruptions to the messages whould I expect? How long would it take to failover and will the messages be lost or fail-ed over to the passive node?
3.Lastly, what happens is the second active node fails as well? Would the cluster be able to continue functioning with only 1 active node?
Thanks in advance! |
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| jefflowrey |
| Posted: Wed Feb 20, 2008 7:36 am Post subject: |
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Grand Poobah
Joined: 16 Oct 2002
Posts: 19981
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| Vitor |
| Posted: Wed Feb 20, 2008 7:37 am Post subject: Re: MSCS failover scenario |
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Grand High Poobah
Joined: 11 Nov 2005
Posts: 26093
Location: Texas, USA
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| lcw82 wrote: |
| I heard about MQ manager clustering. Is it normally advisable to run MQ manager clustering on top of OS clustering? |
Yes, they're used for 2 different things and have 2 different purposes.
| lcw82 wrote: |
| Are there any load balancing with MSCS, or do I need to configure NLB or add an external load-balancer? |
You'd use the WMQ cluster for load balancing, not MSCS (which doesn't, so far as I'm aware, load balance).
| lcw82 wrote: |
| During failover, what kind of disruptions to the messages whould I expect? How long would it take to failover and will the messages be lost or fail-ed over to the passive node? |
If you've set it up correctly, there should be minimal outage and no message loss.
| lcw82 wrote: |
| Lastly, what happens is the second active node fails as well? Would the cluster be able to continue functioning with only 1 active node? |
Yes, but it's not a recommended configuration. Every effort should be made to bring a second active node up asap.
The Clustering manual will explain all aspects of configuration, and the load balancing options available.
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Honesty is the best policy.
Insanity is the best defence. |
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| PeterPotkay |
| Posted: Wed Feb 20, 2008 8:11 am Post subject: |
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Poobah
Joined: 15 May 2001
Posts: 7722
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I've only done 2 node MSCS clusters. Active / Passive where QM1 runs on Node A and can automatically failover to Node B which is just waiting for work. I also have "Active / Active" where I have 2 seperate unrelated QMs running on each node and both can failover to the other node if needed so that both may find themselves running on the same node.
The failover takes about a minute. The more connections you have to the QM, the more persistent messages in the queues the longer it will take. A Broker takes longer on top of that. You will not lose persistent messages.
If you have a 3 node cluster and 2 nodes fail I assume the remaining node will be able to handle the workload although performance may suffer. Depends on how much hardware you throw at it.
At MQ 6.0 make sure you have Hot Fix IC52378 otherwise your clusters may be failing over unexpectedly.
http://www-1.ibm.com/support/docview.wss?uid=swg1IC52378
_________________
Peter Potkay
Keep Calm and MQ On |
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| lcw82 |
| Posted: Thu Feb 21, 2008 6:50 am Post subject: |
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Newbie
Joined: 20 Feb 2008
Posts: 2
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Hey Peter,
When you say the failover takes about 1 minute, does that apply to active/passive, or active/active?
I suppose the latter would have better failover time, and there are some sort of load-balancing going on between them? btw do we need to use any hardware load balancers or set up NLB to do load-balancing?
Thanks! |
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| jefflowrey |
| Posted: Thu Feb 21, 2008 6:55 am Post subject: |
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Grand Poobah
Joined: 16 Oct 2002
Posts: 19981
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Active/Active is just overlapped Active/Passive.
The failover time of an individual unit is completely independent of any other factors - it's strictly the amount of time it takes to a) shut down the unit, b) move the unit's resources, c) start up the unit in the new location.
It would save you time, and from getting annoyed at us, if you try to answer your own questions before you post them.
In general, the sequence should go Read->Think->Try->Ask.
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| PeterPotkay |
| Posted: Thu Feb 21, 2008 10:39 am Post subject: |
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Poobah
Joined: 15 May 2001
Posts: 7722
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MSCS does not provide any load balancing for MQ. The QM runs on either Node 1 or Node 2 at any give time. If you coose to you can have a second unrelated differently named QM run on the other node. Both may find themselves running on the same node if one of the nodes goes down.
If you have a QM on each node you can put them in an MQ cluster to achive MQ load balancing of new work, or put incoming MQ Clients behind a NLB so that their connection attempts get split between the 2 Queue Managers, reagrdless of which node(s) they are running on.
That's why I put "Active / Active" in quotes. You don't have a single QM running on both nodes at the same time and having MSCS distribute the work. Jeff's term of overlapping Active / Passive is a good way of looking at it.
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Peter Potkay
Keep Calm and MQ On |
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