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Mirroring restore rate very low (< 5 MB/sec) - database mirror stuck in "synchronizing" state for several hrs Expand / Collapse
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Posted Monday, July 16, 2012 3:13 PM
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A production mirroring session started synchronizing this morning and at first the restore rate on the mirror server was at about 30 MB /sec.
Suddenly it dropped to < 5 MB /sec and has stayed like this for most of the day.

As a result, the mirror has been in "synchronizing" status for most of the day, and we are unable to create snapshots for reporting users.

What could be the cause of such a low restore rate?
What should I be looking for?

Any links/suggestions would be most welcome.


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Post #1330430
Posted Monday, July 16, 2012 3:23 PM


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Just some random thoughts:

Check the disks for contention
Check to see if anything else is running on the box and consuming inordinate CPU and/or memory
Make sure your anti-virus software isn't on and attempting to scan your database files
check the sql server for blocked processes
Depending on how far the data is travelling, you might have to have your network folks take a look at the traffic between source and mirror




And then again, I might be wrong ...
David Webb
Post #1330432
Posted Tuesday, July 17, 2012 12:45 AM
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I think the above all is sufficient to get the culprit
but mostly It would be Network Bandwidth

Thanks
S.R.Kundur
Post #1330533
Posted Tuesday, July 17, 2012 2:41 AM
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Thanks both for your suggestions.

__________________________________________________________________________________

Turbocharge Your Database Maintenance With Service Broker: Part 2
Turbocharge Your Database Maintenance With Service Broker: Part 1
Real-Time Tracking of Tempdb Utilization Through Reporting Services
Monitoring Database Blocking Through SCOM 2007 Custom Rules and Alerts
Preparing for the Unthinkable - a Disaster/Recovery Implementation
Post #1330579
Posted Tuesday, July 17, 2012 11:11 AM


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There is also a bug related to this (though I don't know if a KB has been published Try stopping and starting the mirroring queues to see if it resolves the problem. If not, continue investigating and consider opening a case with PSS.



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Post #1330903
Posted Wednesday, July 18, 2012 3:04 AM
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Robert Davis (7/17/2012)
There is also a bug related to this (though I don't know if a KB has been published Try stopping and starting the mirroring queues to see if it resolves the problem. If not, continue investigating and consider opening a case with PSS.


Thank you for the suggestion.
Do you mean suspend and resume the mirroring session?
I will try that next time this happens.


__________________________________________________________________________________

Turbocharge Your Database Maintenance With Service Broker: Part 2
Turbocharge Your Database Maintenance With Service Broker: Part 1
Real-Time Tracking of Tempdb Utilization Through Reporting Services
Monitoring Database Blocking Through SCOM 2007 Custom Rules and Alerts
Preparing for the Unthinkable - a Disaster/Recovery Implementation
Post #1331314
Posted Wednesday, July 18, 2012 9:10 AM


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No I meant stop/start the mirroring endpoints. Use an Alter Endpoint caommand and do it on both partners.



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Post #1331547
Posted Wednesday, July 18, 2012 8:56 PM
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Robert Davis (7/18/2012)
No I meant stop/start the mirroring endpoints. Use an Alter Endpoint caommand and do it on both partners.


Thanks for clarifying, now I know what you mean; will try that.


__________________________________________________________________________________

Turbocharge Your Database Maintenance With Service Broker: Part 2
Turbocharge Your Database Maintenance With Service Broker: Part 1
Real-Time Tracking of Tempdb Utilization Through Reporting Services
Monitoring Database Blocking Through SCOM 2007 Custom Rules and Alerts
Preparing for the Unthinkable - a Disaster/Recovery Implementation
Post #1331889
Posted Saturday, July 21, 2012 9:40 PM
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Could the slow restore rate be caused by high file fragmentation on the mirror server?
Perhaps we are due for a file defrag outage.


__________________________________________________________________________________

Turbocharge Your Database Maintenance With Service Broker: Part 2
Turbocharge Your Database Maintenance With Service Broker: Part 1
Real-Time Tracking of Tempdb Utilization Through Reporting Services
Monitoring Database Blocking Through SCOM 2007 Custom Rules and Alerts
Preparing for the Unthinkable - a Disaster/Recovery Implementation
Post #1333433
Posted Saturday, July 21, 2012 10:55 PM


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Marios Philippopoulos (7/21/2012)
Could the slow restore rate be caused by high file fragmentation on the mirror server?
Perhaps we are due for a file defrag outage.


No file level fragmentation would cause a slow degradation of performance, not a sudden one.




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