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| Cluster and HA concept |
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| credito |
 Posted: Tue Nov 04, 2008 6:37 am Post subject: Cluster and HA concept |
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Newbie
Joined: 23 Oct 2008
Posts: 9
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Hi,
We are discussing some concepts using cluster which should be HA (without additional software). The messages should be received only once. Messages trapped on a broken QM are OK. This permits our scenario. It would be great if I could get some feedback of our concept.
We have multiple applications on several host which use MQ 6.x to communicate.
Currently our favorite concept is as follow:
Each sending application has a queue manager (name SendQM) on the same host. This QM has no queues (beside system queues) We assume for each sending app there is a backup server with the application and a QM ready, which has to be started manually.
On another box a further QM is installed (name CentralQM1) which hosts multiple local queues. CentralQM1 has a clone CentralQM2 on a different box. Both have the same local queues. Lets say there is a local queue centQue on CentralQM1 and CentralQM2.
If one of the central QM fails the other one will be still available.
Receiving applications have another local queue manager (name RecvQM) on the same host the receiving app is running. All QMs are in a cluster.
The sending and receiving application can only connect to one QM.
Once an application wants to send a message, the message is put to SendQM which just "forwards" the message to centQueue either on CentralQM1 or on CentralQM2.
The receiving application should receive the message from the QM RecvQM ( the app cannot use CenralQM1 or CentralQM2) as it does not know where the message is. If the receiving application fails there is also another system with the application and a queue manager waiting to be started manually. Our idea is that the RecvQM can be used to get the message from the centQueue queue.
However if I understand MQ correctly it is not possible to use RecvQM to get the message from centQueue from CentralQM1 and CentralQM2. To do that we need a local queue on RecvQM which gets the message from centQueue on CentralQM1 and CentralQM2.
Question1: Can this be done automatically by MQ ? Do we have to use a tool in the support pacs ?
Question2: What do you think about the concept ? I guess this is some kind of standard problem but I couldn't find a common solution for this. Any ideas or pointers to document are highly welcome.
Regards,
Marcel |
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| Vitor |
| Posted: Tue Nov 04, 2008 6:58 am Post subject: |
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Grand High Poobah
Joined: 11 Nov 2005
Posts: 26093
Location: Texas, USA
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It's an odd solution where your HA solution can potentially lose messages, but ok.
I'm struggling to see what these central queue managers are adding to your solution. As I see it, you have a series of sending apps each with a dedicated queue manager. You have a manual failover for these. These send messages destined for a receiving application, which again has a dedicated queue manager and a manual failover solution.
Why have the central queue managers? Why not cluster sending and receiving queue managers? Messages will flow without this odd middle step. What am I missing here that requires an central hub?
Also in your solution you'd either need an application or some aliasing to move the message from centQueue to the recieving queue.
_________________
Honesty is the best policy.
Insanity is the best defence. |
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| credito |
| Posted: Tue Nov 04, 2008 7:09 am Post subject: |
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Newbie
Joined: 23 Oct 2008
Posts: 9
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Hi Vitor,
thank you for your reply.
The idea is the central QMs are hosted on different sites, so if one server room dies the other one is still there. We do not have to change the MQ setup in this scenario (ok we probably have to because in the failed server room is a part of the applications).
But I guess you are right, just skip the centralQM1 and centralQM2 and we have a better solution. If we have a clone of the RecvQM we just have to bring that online once the original RecQ fails and the cluster automatically reroutes ? Am I right about this ?
How long does this take in common (seconds, minutes ?) |
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| PeterPotkay |
| Posted: Tue Nov 04, 2008 7:26 am Post subject: Re: Cluster and HA concept |
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Poobah
Joined: 15 May 2001
Posts: 7722
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| credito wrote: |
| The receiving application should receive the message from the QM RecvQM ( the app cannot use CenralQM1 or CentralQM2) as it does not know where the message is. |
Eliminate RecvQM from your design.
Have 4 instances of your receiving app, each running in MQ Client mode.
2 instances of ReceivingApp running on Server1 in Data Center 1. One connects to CentralQM1 and the other connects to CentralQM2.
2 instances of ReceivingApp running on Server2 in Data Center 2. One connects to CentralQM1 and the other connects to CentralQM2.
If CentralQM1 goes down, no problem, you still have Central QM2.
If CentralQM2 goes down, no problem, you still have Central QM1.
If Server1 goes down, no problem, you still have Server2 with its 2 threads watching both CentralQM1 or CentralQM2.
If Server2 goes down, no problem, you still have Server1 with its 2 threads watching both CentralQM1 or CentralQM2.
For all NEW work you have very high availability. Any one of the 4 servers can go down and the front end won't care. But due to the possability of marooned messages, you cannot and should not call this an H.A. solution.
_________________
Peter Potkay
Keep Calm and MQ On |
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| credito |
| Posted: Wed Nov 05, 2008 8:04 am Post subject: |
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Newbie
Joined: 23 Oct 2008
Posts: 9
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Hi Peter,
thank you for your answer. Your solution sounds great but unfortunately the application does not support multiple connections. The app connects to only one queue and I cannot run multiple instances from the app. Stupid I know but it's the truth.
Best regards,
Marcel |
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| Vitor |
| Posted: Wed Nov 05, 2008 8:28 am Post subject: Re: Cluster and HA concept |
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Grand High Poobah
Joined: 11 Nov 2005
Posts: 26093
Location: Texas, USA
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| PeterPotkay wrote: |
| But due to the possability of marooned messages, you cannot and should not call this an H.A. solution. |
_________________
Honesty is the best policy.
Insanity is the best defence. |
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| m4c0 |
| Posted: Mon Nov 10, 2008 4:56 am Post subject: |
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Novice
Joined: 07 Nov 2008
Posts: 17
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Credito,
Do you need load balancing or just "HA"? |
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