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MQSeries.net Forum Index » General IBM MQ Support » Recovery

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MQSheriff
PostPosted: Wed Jun 19, 2002 11:38 am    Post subject: Recovery Reply with quote

Newbie

Joined: 14 May 2002
Posts: 3

I have the following Questions concerning Recovery:

1. How to perform Media Recovery of the Complete Queue Manager if all the Data files pertaining to Queue Manager are deleted. I tried rcrmqobj, but since the Queue Manager itself is gone I am not able to do the Recovery

2. Where are the Messages stored once the file for Queue is Deleted, cause I am still able to Put / Get to the Queue, only after QMgr restart do the changes take effect and the Queue becomes unavailable. Please note that for a Persistent Queue the change is taken into account immediatly

3. What is the actual use of the Actual use of rcdmqimg command ? Please give me a practical example if possible

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Aejaz Sheriff

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bduncan
PostPosted: Wed Jun 19, 2002 2:05 pm    Post subject: Reply with quote

Padawan

Joined: 11 Apr 2001
Posts: 1554
Location: Silicon Valley

Hmm... In answer to your first question, if ALL data files pertaining to a queue manager (typically everything in the /var/mqm/qmgrs/qmgrname directory on UNIX) are deleted, then there is no record of the queue manager left on that machine whatsoever. If these files have been backed up, then restoring the entire directory should recover the queue manager to whatever state it was in when the backup was taken without the need for any special recovery programs (like rcrmqobj).

As far as your second question, as the name non-persistent indicates, the queue manager only stashes these messages in memory, not on disk (unless they are part of a UOW I believe - but then why on earth would you require syncpoint for non-persistent messages anyway?) This is why you can continue to interact with the queue even though its queue file has been deleted.

And your third question, I've never actually used rcdmqimg, so hopefully someone else will be able to provide an answer...
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nimconsult
PostPosted: Wed Jun 19, 2002 10:58 pm    Post subject: Reply with quote

Master

Joined: 22 May 2002
Posts: 268
Location: NIMCONSULT - Belgium

The "rcdmqimg" is used to take a snapshot of queue manager objects.

When you run the command, MQ Series takes a snapshot of the specified object in the log. In case of media recovery of an object (when the file or files associated to the object are lost or corupted), MQ Series will find the latest snapshot of the object in the log files and rebuild the object.

Taking a media image only works for queue managers with linear logging and not circular logging. The reason is simple: with circular logging, MQ Series reuses log files and would destroy your media images. Conclusion: no media recovery available with circular logging.

For a queue manager with linear logging, you need to take a media image of all the queue manager objects periodically with the "rcdmqimg" command, otherwise you will never be able to clean your log files and will fill your disks endlessly. When you run the "rcdmqimg" command, MQ Series gives you the name of the oldest log file required to perform media recovery. All the log files older than this file can be deleted.

The usual configuration of a production system is to set-up your queue manager with linear logging, and schedule a daily (or weekly) procedure of "rcdmqimg" followed by a cleaning of the useless log files. IBM proposes a support pac with a sample of such a procedure.
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MQSheriff
PostPosted: Thu Jun 20, 2002 11:18 am    Post subject: Reply with quote

Newbie

Joined: 14 May 2002
Posts: 3

I tried restoring the files from backup but still the Queue Manager does not start the command strmqm does not recoganise the Queue Manager. The command rcrmqobj also does not help.

Could you please tell me what is the support pac availale from IBM for automating taking media snapshots as reported
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nimconsult
PostPosted: Thu Jun 20, 2002 10:09 pm    Post subject: Reply with quote

Master

Joined: 22 May 2002
Posts: 268
Location: NIMCONSULT - Belgium

Ths following support pacs may be of interest to you for your backup & recovery procedures:

MS03: MQSeries save Queue Manager object definitions using PCFs

MS62: MQSeries - Linear log clean-up script

MS65: MQSeries - Configuration back-up script

This does not solve your current problem, but give you the tools to avoid the problem in the future.

Regards,
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