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| phitchman |
 Posted: Tue Jun 24, 2003 8:45 am Post subject: rcdmqimg and stopping channels |
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Novice
Joined: 14 Mar 2003
Posts: 14
Location: London
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Hi,
We have been getting to grips with backups. According to the MQSeries Backup and Recovery book the queue managers channels should be stopped before running the rcdmqimg command, but it does not explain why. Is this actually necessary and if so why?
Thanks
Pete
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P.J. Hitchman |
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| mqonnet |
| Posted: Tue Jun 24, 2003 11:53 am Post subject: |
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Grand Master
Joined: 18 Feb 2002
Posts: 1114
Location: Boston, Ma, Usa.
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I believe the reason is when you run RCDMQIMG, and it tries to record an image of an object off your queue manager but finds that the queue is in use it fails. And hence to avoid such failover situations you should end your channels. Because the transmission queues are always opened by the mca.
Hope this helps.
Cheers
Kumar |
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| PeterPotkay |
| Posted: Tue Jun 24, 2003 11:58 am Post subject: |
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Poobah
Joined: 15 May 2001
Posts: 7722
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Kumar, I was thinking the same thing, but the Sys Admin Guide says that this command can be issued against a running QM, which to me indicates messages going in and out of queues. Maybe stopping the channels helps lower the amount of change during the run of the command?
| Code: |
rcdmqimg (record media image)
Purpose
Use the rcdmqimg command to write an image of an object, or group of objects, to the log for use in media recovery. Use the associated command rcrmqobj to recreate the object from the image.
You use this command with an active queue manager. Further activity on the queue manager is logged so that, although the image becomes out of date, the log records reflect any changes to the object.
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Peter Potkay
Keep Calm and MQ On |
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| mqonnet |
| Posted: Tue Jun 24, 2003 1:00 pm Post subject: |
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Grand Master
Joined: 18 Feb 2002
Posts: 1114
Location: Boston, Ma, Usa.
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Peter you are right. I was thinking about rcrmqobj instead. Even though the validation seemed appropriate, it still needs substasive backup.
Which leads to the question of where is the mention of "channels asked to stop" while running rcdmqimg. I dont see any reference anywhere. May be i am missing it.
Recording an image itself means that it has no bearing on any object openers and the same goes with the MCA as well. Hence i would go back to my question and that is, where is the doc that says so.
Cheers
Kumar |
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| jhalstead |
| Posted: Wed Jun 25, 2003 12:45 am Post subject: |
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Master
Joined: 16 Aug 2001
Posts: 258
Location: London
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To echo the preceding comments, it makes sense to me. By using rcdmqimg we're taking a shapshot of the contents of the queues and writing this to the linear log files. If the channels are up and running messages could leave the qmgr or messages could arrive. So this is the best practice and cleanest way of doing it.
At the end of the day you're using linear logging for a reason - i.e. wanting the absolutely best chance of being able to recover messages if an object becomes damaged. As there is no doubt a compelling business reason for this I wouldn't take and chances and I'd shut down the channels & stop any MQSeries application which interact with the queue before doing a rcdmqimg.
Ta
Jamie |
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| phitchman |
| Posted: Wed Jun 25, 2003 3:36 am Post subject: |
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Novice
Joined: 14 Mar 2003
Posts: 14
Location: London
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Hi,
The document I read about shutting down the channels before doing a rcdmqimg is this one:
http://www.redbooks.ibm.com/redbooks/pdfs/sg245222.pdf
I posed the question because this red book dates back to 1998 and because there is no mention of this issue in other documentation, so I was wondering if it was really necessary or if rcdmqimg effectively takes a consistent snapshot of the objects it records.
Thanks for the feedback.
Pete
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P.J. Hitchman |
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