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| guest468 |
 Posted: Mon Aug 10, 2009 6:20 am Post subject: Active log deletion |
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Centurion
Joined: 30 May 2006
Posts: 146
Location: NY
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Hi Guys,
I was trying to understand what would happen to inflight messages if an active log file which is being presently being used(modified) by the qmgr is deleted. What are the chances of message loss?
I am not even sure if the QMGR is still technically active or shutdown (though I could see many processes still running)
Thanks, |
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| exerk |
| Posted: Mon Aug 10, 2009 6:27 am Post subject: |
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Jedi Council
Joined: 02 Nov 2006
Posts: 6339
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From what I can remember, deleting active logs will not necessarily bring down a queue manager, but restarting it after shut down, or pre-emptive shut-down is a non-starter.
Play with a crash-and-burn queue manager to verify the above, but I'm sure someone will be along in a bit to expand on the above.
_________________
It's puzzling, I don't think I've ever seen anything quite like this before...and it's hard to soar like an eagle when you're surrounded by turkeys. |
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| Vitor |
| Posted: Mon Aug 10, 2009 6:44 am Post subject: |
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Grand High Poobah
Joined: 11 Nov 2005
Posts: 26093
Location: Texas, USA
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The messages should still be in a q file (subject to persistence and other considerations) but the integrity of the queue manager will be compromised.
If the file's being modified then it's good odds the queue manager was running. Note that from the inside, a queue manager is just many processes running (i.e., there isn't a qmgr.exe)
OS security is the way to go here; prevention better than cure and all that. If you take up the suggestion of my most worthy associate and try it someplace do post what actually happens.
_________________
Honesty is the best policy.
Insanity is the best defence. |
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| guest468 |
| Posted: Mon Aug 10, 2009 7:43 am Post subject: |
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Centurion
Joined: 30 May 2006
Posts: 146
Location: NY
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q file is fine. I am interested in the fate of in-flight messages. (and I am talking about persistent messages only)
btw, I am not sure how you can restrict access to active logs from OS side? mqm user does need write access there. And I am not aware of doing mq admin outside of that user/group.
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| Vitor |
| Posted: Mon Aug 10, 2009 8:39 am Post subject: |
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Grand High Poobah
Joined: 11 Nov 2005
Posts: 26093
Location: Texas, USA
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| guest468 wrote: |
| q file is fine. I am interested in the fate of in-flight messages. (and I am talking about persistent messages only) |
Persistent in-flight messages will still be in a source queue file until the UOW is committed.
| guest468 wrote: |
| btw, I am not sure how you can restrict access to active logs from OS side? mqm user does need write access there. And I am not aware of doing mq admin outside of that user/group. |
Then you're on exactly the right method. Some sites in my experience open up this path to a wider group who may not entirely understand the significance.
Of course, it remains important to restrict membership of the mq admin group to trained people. Or at least people who think before deleting stuff.
_________________
Honesty is the best policy.
Insanity is the best defence. |
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| PeterPotkay |
| Posted: Mon Aug 10, 2009 9:18 am Post subject: |
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Poobah
Joined: 15 May 2001
Posts: 7722
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| Vitor wrote: |
| guest468 wrote: |
| q file is fine. I am interested in the fate of in-flight messages. (and I am talking about persistent messages only) |
Persistent in-flight messages will still be in a source queue file until the UOW is committed.
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The real question being will the MQCMIT call (or MQBACK call) work if the MQ Logs are gone.
_________________
Peter Potkay
Keep Calm and MQ On |
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| Vitor |
| Posted: Mon Aug 10, 2009 9:24 am Post subject: |
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Grand High Poobah
Joined: 11 Nov 2005
Posts: 26093
Location: Texas, USA
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| PeterPotkay wrote: |
| Vitor wrote: |
| guest468 wrote: |
| q file is fine. I am interested in the fate of in-flight messages. (and I am talking about persistent messages only) |
Persistent in-flight messages will still be in a source queue file until the UOW is committed.
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The real question being will the MQCMIT call (or MQBACK call) work if the MQ Logs are gone. |
Hence the message will stay in the queue file.... 
_________________
Honesty is the best policy.
Insanity is the best defence. |
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| gbaddeley |
| Posted: Mon Aug 10, 2009 5:09 pm Post subject: Re: Active log deletion |
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Jedi Knight
Joined: 25 Mar 2003
Posts: 2538
Location: Melbourne, Australia
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| guest468 wrote: |
Hi Guys,
I was trying to understand what would happen to inflight messages if an active log file which is being presently being used(modified) by the qmgr is deleted. What are the chances of message loss?
I am not even sure if the QMGR is still technically active or shutdown (though I could see many processes still running)
Thanks, |
The line of discussion in replies follows the apparent behaviour of MQ, but the bottom line is that the integrity of MQ will be compromised by deleting any active log file. So don't do it, and prepare for DR if it does happen.
_________________
Glenn |
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