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| Yogesh |
 Posted: Mon Mar 13, 2006 10:39 am Post subject: Deleting Log files |
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Newbie
Joined: 26 Dec 2005
Posts: 8
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Hi All,
I read in System Admin guide that a QM will "not issue any errors and continue to process data including persistent messages" when the active log files of the QM are deleted. But if MQ saves all the persistent messages in the logs then how can QM run and "process" data without logs.
Thanks in advance.
Yogesh |
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| wschutz |
| Posted: Mon Mar 13, 2006 11:08 am Post subject: |
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Jedi Knight
Joined: 02 Jun 2005
Posts: 3316
Location: IBM (retired)
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can you give a chapter and section where this statement is given?
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-wayne |
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| sandiksk |
| Posted: Mon Mar 13, 2006 11:10 am Post subject: |
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Centurion
Joined: 08 Jun 2005
Posts: 133
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| I see it in 14th chapter pg 206. Interesting point yogesh. |
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| Yogesh |
| Posted: Mon Mar 13, 2006 11:13 am Post subject: |
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Newbie
Joined: 26 Dec 2005
Posts: 8
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Chapter 14 Recovery and Restart
+ Using the log for recovery
+ Protecting WebSphere MQ Log files |
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| fjb_saper |
| Posted: Mon Mar 13, 2006 5:14 pm Post subject: |
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Grand High Poobah
Joined: 18 Nov 2003
Posts: 20756
Location: LI,NY
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That is because the messages are not lost (they are as well in the queue or in memory)and the qmgr is running and writing to the logs normally. To have the messages protected again in such a situation run "rcdmqimg". This will take stock of what is going on and write the messages back to the log after a "fixpoint". It will allow you as well to archive older logs...
Remember only persistent messages are truely protected.
Enjoy 
[Edit] The above procedure is only to be used in the exceptional scenario where the log files have gone missing and before the qmgr can be stopped. Good practice is to keep the log files around and remove files only with a # < min( qmgr restart, recovery start). The above procedure is a hack and not approved by IBM [/Edit] 
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MQ & Broker admin
Last edited by fjb_saper on Mon Mar 13, 2006 5:29 pm; edited 1 time in total |
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| wschutz |
| Posted: Mon Mar 13, 2006 5:23 pm Post subject: |
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Jedi Knight
Joined: 02 Jun 2005
Posts: 3316
Location: IBM (retired)
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Okay, the entire paragrah says:
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| Do not remove the active log files manually when a WebSphere MQ queue manager is running. If a user inadvertently deletes the log files that a queue manager needs to restart, WebSphere MQ does not issue any errors and continues to process data including persistent messages. The queue manager shuts down normally, but can fail to restart. Recovery of messages then becomes impossible. |
I would strongly advise against trying this on "important" mq servers ... there are two supportpacs that can be used to determine which log files can be safely removed.
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-wayne |
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| Yogesh |
| Posted: Tue Mar 14, 2006 10:52 am Post subject: |
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Newbie
Joined: 26 Dec 2005
Posts: 8
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fjb_saper wrote
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That is because the messages are not lost (they are as well in the queue or in memory)and the qmgr is running and writing to the logs normally
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How can the qmgr write to the logs if they donot exist. AMQHASMX process should fail as it wont be able to write into the logs. |
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| jefflowrey |
| Posted: Tue Mar 14, 2006 11:24 am Post subject: |
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Grand Poobah
Joined: 16 Oct 2002
Posts: 19981
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It is possible for an output handle to exist even though the file it points to doesn't. The handle will still accept data to be written, the data will just go no where.
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I am *not* the model of the modern major general. |
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| Yogesh |
| Posted: Tue Mar 14, 2006 11:30 am Post subject: |
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Newbie
Joined: 26 Dec 2005
Posts: 8
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Ok
That means for MQ it will still asume that logs are there and keeps logging data although it is not written anywhere. Now if i recycle the qmgr using a dummy qmgr then will the persistent messages in the queues survive ?? I think they should as they are present in queue files. Am i right ??
Thanks all for ur replies.
Yogesh |
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| jefflowrey |
| Posted: Tue Mar 14, 2006 11:35 am Post subject: |
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Grand Poobah
Joined: 16 Oct 2002
Posts: 19981
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The only supported option you have when you have lost log files is to delete the queue manager and rebuild it.
All other solutions may or may not function - but will not be supported as I understand it.
In the extraordinary situation where you have lost production log files but have persistent messages that need to be retained - you should immediately open a PMR and work with IBM support to resolve this as best you can. Likely this will involve using a utility to move the persistant messages to another qmgr or a file or something, and then restoring the messages after you have rebuilt the queue manager.
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I am *not* the model of the modern major general. |
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| kevinf2349 |
| Posted: Tue Mar 14, 2006 11:37 am Post subject: |
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Grand Master
Joined: 28 Feb 2003
Posts: 1311
Location: USA
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Yogesh
Read the last part of Wayne's post quoting the manual
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| The queue manager shuts down normally, but can fail to restart. Recovery of messages then becomes impossible. |
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| ma.eyal |
| Posted: Wed Mar 15, 2006 6:42 am Post subject: |
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Novice
Joined: 13 Sep 2005
Posts: 15
Location: Israel
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| Yogesh wrote: |
| Now if i recycle the qmgr using a dummy qmgr then will the persistent messages in the queues survive ?? I think they should as they are present in queue files. Am i right ?? |
The old queue files will not be correct with a new dummy queue manager. They will be intact but the queue manager will look at them as "currepted".
If you lose the log files but the queue manager is still up, you can try to transfer the messages from the damaged queue manager to another one by using a simple program.
That is the only option you can get that I know of.
If the queue manager crashes (usually the case, since not writing to the logs is a critical and should crash it), as stated, open an emergency PMR. |
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