You are comparing MQ Cluster and MQ List? Do you mean distribution list? Clustering and distribution lists are not related. A distribution list puts the same message to more than one queue. In a cluster you only put one message to one queue. In a cluster you can have a queue on more than one queue manager by the same name within a cluster. When you do a put, it will only put the message to one of the queues in the cluster. When you open the cluster queue, it will either open one of them in the cluster and put all messages with that object handle to one queue, or it can put the message to all queues in a round-robin fashion, depending on the option chosen in your open options.
Now that's out of the way.
The main advantage to clustering is job security because it can be very high maintenance. So if you need to create work for yourself, add clustering. Not everyone has had a bad experience with clustering, but I think everyone will agree it is sometimes difficult to maintain and troubleshoot. With every release, IBM says clustering was bad in the previous release but now it is better. I have not had the chance to test it in 5.3 yet though. Clustering gives you a cheap way to balance your workload across queue managers (probably across machines) so you can scale your application. I say it is the cheap way because it is not balanced, it is round-robin. If you have a complex network with many to many connections, clustering can reduce the number of channel definitions. This is because it creates channels as needed automagically. I have used clustering for this purpose before. If a queue manager becomes unavailable, it routes all messages to the remaining available queue managers. This is cheap availability but not good for HA because messages will get stuck on the failed queue manager. Also, it doesn't react to the queue manager's availability very well and sometimes messages get stuck.
You should carefully evaluate if clustering is right for your architecture. Do not use it just because it is cool or because some IT director thinks it will solve all your problems. The main advantages are:
- Spread workload across queue managers
- Provides a cheap, but unreliable psuedo-failover solution
- An application can easily put a message on a queue on another queue manager without altering the queue manager
- Can be more or less administration depending on your luck
What about distribution lists? They are good if you want to send the same message to many queues on many queue managers. With this, you can put the message once rather than 20 times. It is a useful feature. If you need to send the same message to many places also consider pub/sub if that meets your needs.
Mike Murphy
Sr. Middleware Consultant
http://www.mqsolutions.com
Office: 562-902-7800
Cell: 602-741-6689
Idamar Ferreira <[EMAIL PROTECTED]> wrote:
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Date Recieved:
| 11/04/2002 11:49:39 AM | |
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| [EMAIL PROTECTED] | |
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Subject:
| Why MQ Cluster or MQ List |
Hi all,
Does someone know what I take advantage using
a MQ Cluster?
Why do I have to use MQ Cluster?
Would I consider use MQ List?
Please don't consider the beneficts for administration.
TIA
Idamar Ferreira
Especialista - GEROP - CAIXA
mailto:[EMAIL PROTECTED]
((61)414-4935
"Take care of your People, They are the unique unrecoverable piece of your business"
.
