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Message
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| pshan81 |
 Posted: Mon Dec 22, 2008 3:30 am Post subject: Queue Manager Recovery and Restart |
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Acolyte
Joined: 24 May 2005
Posts: 72
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Hi,
I have observed the below behaviour of the qmgr while working out recovery and restart mechanisms.
1) Able to recover a corrupted/deleted queue file using rcrmqobj command even without using rcdmqimg for the queue (All the persistent messages were restored)
When is rcdmqimg really useful? Any instances where media images need to be recorded manually?
2) rcdmqimg applies to all MQ objects like qmgr,queue,channel,services etc.However, rcrmqobj command doesnot accept the type qmgr.Even the below command recovers all objects except qmgr.Why?
rcrmqobj -m QMGR -t all *
3) The corrupted qmgr file is restored after restarting the qmgr.Is it an example of how Websphere MQ automatically recovers some objects from their media image?Any other instances where Websphere MQ does this automatic recovery?
Thanks a lot |
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| Vitor |
| Posted: Mon Dec 22, 2008 3:47 am Post subject: Re: Queue Manager Recovery and Restart |
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Grand High Poobah
Joined: 11 Nov 2005
Posts: 26093
Location: Texas, USA
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| pshan81 wrote: |
1) Able to recover a corrupted/deleted queue file using rcrmqobj command even without using rcdmqimg for the queue (All the persistent messages were restored)
When is rcdmqimg really useful? Any instances where media images need to be recorded manually?
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rcdmqimg records the object definitions (the queues themselves) not the messages. Persistent messages are logged automatically under all circumstances. You'd use rcdmqimg where you're using linear logging for recovery. This is a documented thing.
| pshan81 wrote: |
| 2) rcdmqimg applies to all MQ objects like qmgr,queue,channel,services etc.However, rcrmqobj command doesnot accept the type qmgr.Even the below command recovers all objects except qmgr.Why? |
Because a queue manager is a discrete object which owns the logs. If the queue manager (which is just a set of processes) was corrupt, what would run the logs forward and restore the objects?
| pshan81 wrote: |
| 3) The corrupted qmgr file is restored after restarting the qmgr.Is it an example of how Websphere MQ automatically recovers some objects from their media image?Any other instances where Websphere MQ does this automatic recovery? |
As documented.
_________________
Honesty is the best policy.
Insanity is the best defence. |
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| exerk |
| Posted: Mon Dec 22, 2008 4:25 am Post subject: Re: Queue Manager Recovery and Restart |
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Jedi Council
Joined: 02 Nov 2006
Posts: 6339
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| pshan81 wrote: |
| When is rcdmqimg really useful? Any instances where media images need to be recorded manually? |
To expand on Vitor's comment, it's useful for 'moving' the first checkpoint log needed for media recovery to a later log in the chain, which can make log management easier.
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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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| Sam Uppu |
| Posted: Tue Dec 23, 2008 8:16 am Post subject: Re: Queue Manager Recovery and Restart |
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Yatiri
Joined: 11 Nov 2008
Posts: 610
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| Vitor wrote: |
| pshan81 wrote: |
1) Able to recover a corrupted/deleted queue file using rcrmqobj command even without using rcdmqimg for the queue (All the persistent messages were restored)
When is rcdmqimg really useful? Any instances where media images need to be recorded manually?
|
rcdmqimg records the object definitions (the queues themselves) not the messages. Persistent messages are logged automatically under all circumstances. You'd use rcdmqimg where you're using linear logging for recovery. This is a documented thing.
| pshan81 wrote: |
| 2) rcdmqimg applies to all MQ objects like qmgr,queue,channel,services etc.However, rcrmqobj command doesnot accept the type qmgr.Even the below command recovers all objects except qmgr.Why? |
Because a queue manager is a discrete object which owns the logs. If the queue manager (which is just a set of processes) was corrupt, what would run the logs forward and restore the objects?
| pshan81 wrote: |
| 3) The corrupted qmgr file is restored after restarting the qmgr.Is it an example of how Websphere MQ automatically recovers some objects from their media image?Any other instances where Websphere MQ does this automatic recovery? |
As documented. |
Is there any advantage of using 'rcdmqimg' command than using saveqmgr script. Is there any advantage of using 'rcdmqimg'?. I know that the saveqmgr can be used for both linear and circular and rcdmqimg is used only for linear.
I believe when we use 'rcdmqimg' will recover the msgs from linear logs after recovering which wont happen with restoring from saveqmgr file. plz correct/ confirm.
Thanks for clearing my confusion. |
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| exerk |
| Posted: Tue Dec 23, 2008 8:24 am Post subject: Re: Queue Manager Recovery and Restart |
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Jedi Council
Joined: 02 Nov 2006
Posts: 6339
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| Sam Uppu wrote: |
Is there any advantage of using 'rcdmqimg' command than using saveqmgr script. Is there any advantage of using 'rcdmqimg'?. I know that the saveqmgr can be used for both linear and circular and rcdmqimg is used only for linear.
I believe when we use 'rcdmqimg' will recover the msgs from linear logs after recovering which wont happen with restoring from saveqmgr file. plz correct/ confirm.
Thanks for clearing my confusion. |
Already covered in Vitor's and my earlier post...
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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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| mqjeff |
| Posted: Tue Dec 23, 2008 11:12 am Post subject: |
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Grand Master
Joined: 25 Jun 2008
Posts: 17447
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Saveqmgr does absolutely nothing with the logfiles.
This is why it doesn't care if they are linear or circular. |
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