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| RAJESHRAMAKRISHNAN |
 Posted: Sat Sep 02, 2017 6:55 am Post subject: MQ Active logs in Windows |
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Voyager
Joined: 01 May 2004
Posts: 96
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We have queue managers in Windows, AIX and Linux environments. While I see the active logs are getting updated (Last updated time stamp changing) rapidly in Aix and Linux, in windows I don't see them even being used (Though we use persistent messages). My understanding is that all the transactions would get recorded in the active logs before being committed to the Q.
For my own experiments, I created queue managers in windows and channels between them. Pumped hundreds of persistent messages(Big and Small) between them but could not see any active logs being updated in source or target queue managers. It gets updated only when I restart the QMs.
Can some one explain this behavior? Thanks very much |
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| bruce2359 |
| Posted: Sat Sep 02, 2017 1:12 pm Post subject: |
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Poobah
Joined: 05 Jan 2008
Posts: 9469
Location: US: west coast, almost. Otherwise, enroute.
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Explain "getting updated." Are you talking about file date/time stamps? File byte length?
If you run the dmpmqlog utility, is there nothing in the files?
Please be more precise.
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| RAJESHRAMAKRISHNAN |
| Posted: Sat Sep 02, 2017 10:03 pm Post subject: |
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Voyager
Joined: 01 May 2004
Posts: 96
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Hello Bruce
Thanks for the reply. Yes, the timestamp not getting updated. I know that length would be same |
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| PeterPotkay |
| Posted: Sun Sep 03, 2017 4:51 am Post subject: |
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Poobah
Joined: 15 May 2001
Posts: 7722
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| tczielke |
| Posted: Sun Sep 03, 2017 5:01 am Post subject: |
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Guardian
Joined: 08 Jul 2010
Posts: 941
Location: Illinois, USA
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Just one clarification. The recovery logs (or active logs) have nothing to do with transactions, per se. For example, if you were just using syncpoint on only non-persistent messages, the recovery logs would not be updated. If you are using persistent messages, they will be updated. It is a bit of a misnomer to call them "transaction logs".
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Working with MQ since 2010. |
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| RAJESHRAMAKRISHNAN |
| Posted: Sun Sep 03, 2017 5:14 am Post subject: |
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Voyager
Joined: 01 May 2004
Posts: 96
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Hello Jeff/tczielke and All
Many thanks for all your answers.
Thanks |
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| Andyh |
| Posted: Mon Sep 04, 2017 5:56 am Post subject: |
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Master
Joined: 29 Jul 2010
Posts: 239
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Writing to the recovery logs is VERY performance sensitive, and consequently we'd rather flush the file meta-data as infrequently as possible.
On unix we use O_DSYNC (where appropriate) together with O_DIRECT (where appropriate) to minimize the transaction log writing costs.
On windows we use FILE_FLAG_NO_BUFFERING and FILE_FLAG_WRITE_THROUGH to achieve a similar outcome. |
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