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| fitzcaraldo |
 Posted: Tue Aug 16, 2005 10:11 pm Post subject: rcdmqimg |
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Voyager
Joined: 05 May 2003
Posts: 98
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We are building two machines to act as gateways to a WMQ cluster - each with a single queue manager. The machines themselves will be in a HACMP resource group. Machines outside the cluster will connect to one or the other queue managers to gain access to the cluster.
We have a basic requirement of 24x7 operation and I am trying to reconcile this with a logging strategy on the gateway queue managers. Circular logs are easy but with no recovery for damaged objects (which have been experienced here in the past).
Linear logging will give us media recovery but seems to require stopping all channels first and hence break the 24x7. (We will have up to 1500 channel pairs to each QM)
On a simple test qmanager I can run rcdmqimg quite happily with channels running and don't get any error. Can anyone tell me exactly why it is important to stop the channels first and what are implications of not doing so?
Another consideration is that these QMs are strictly routing machines consisting of lots of XMIT queues which should mostly be empty. On the other hand nearly all traffic is persistent fire and forget with the expected assured delivery.
Any thoughts would be appreciated. |
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| Nigelg |
| Posted: Tue Aug 16, 2005 10:40 pm Post subject: |
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Grand Master
Joined: 02 Aug 2004
Posts: 1046
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You do not have to stop channels, or any other WMQ activity, before running rcdmqimg. Where did you get that misinformation?
What if you have a disk crash? Are you never going to backup your system? You have to stop the qmgr to do the backup.
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| fitzcaraldo |
| Posted: Tue Aug 16, 2005 11:02 pm Post subject: |
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Voyager
Joined: 05 May 2003
Posts: 98
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From the Redbook 'MQSeries Backup and Recovery - SG245222' Section 4.7. This is pretty old. Does it still apply.
Regarding backup. All logs and data are on the SAN and synchronously copied off site as part of the HACMP - so we are considering not doing it. We want to be able to quickly recreate a damaged object if one occurs using replay from the linear logs. |
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| fjb_saper |
| Posted: Wed Aug 17, 2005 10:42 am Post subject: |
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Grand High Poobah
Joined: 18 Nov 2003
Posts: 20756
Location: LI,NY
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In order to do an offline backup you need to stop the qmgr... In the same process it is considered good practice to run the rcdmqimg before shutting the qmgr down after having stopped all channels...
For the space considerations on the logs...
If you are going to use the java support pack MS0L for archiving the linear logs consider having enough space to hold a minimum of 24 hrs of linear logs... (they will not all be active logs... but you might not yet be able to archive them). I got a contact admin surprise that way... filling log space to 100%...
Enjoy  |
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| fitzcaraldo |
| Posted: Wed Aug 17, 2005 6:28 pm Post subject: |
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Voyager
Joined: 05 May 2003
Posts: 98
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| Thanks for that - but does anyone know why you need to stop the channels before the rcdmqimg? |
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| fjb_saper |
| Posted: Wed Aug 17, 2005 6:39 pm Post subject: |
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Grand High Poobah
Joined: 18 Nov 2003
Posts: 20756
Location: LI,NY
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Yes:
It is to have a clean image for offline backup. If you are not doing an offline backup you need not close the channels.
If the activity is not stopped your queues will not be in a consistent state throughout the backup. Thus the need for the offline backup.
Online backup is done by rcdmqimg. It is written to the "log" files (Sxxxxxxx.LOG)... They are used by the qmgr to start and for image recovery in case of damaged objects....
Enjoy |
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