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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, February 18, 2013 7:44 AM
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Did you ever find a solution to this problem? I'm also experiencing very low restore rates, less than 1MB/s.

The unrestored log has only grown by 94MB in 8 minutes, but mirroring just isn't keeping up.

We're running SQL 2012 RTM. We've got a gigabit link between the 2 servers which isn't being touched. Data seems to have been sent to the passive server but its just not applying the transactions to the databases quickly enough.

Also checked disks and only seeing 9MB/s writing to the disks, and they're capable of much more obviously.



Darren
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Posted Tuesday, February 19, 2013 8:22 AM
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darrenstokes (2/18/2013)

Also checked disks and only seeing 9MB/s writing to the disks, and they're capable of much more obviously.


Are they? Right now? How do you know?
Run a quick benchmark locally and across the purported gigabit link both - SQLIO is my favorite quick tool for that, but a basic file copy will work, too. Do it both ways, just in case.

Note that when a disk controller loses its cache, or its battery (which almost always then disabled the cache), you can see a sudden dramatic drop in write performance.

If nothing else, get the HW folks to run online or offline diagnostics on both ends, the end that's being written to first.
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