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 mirroring causing principle slowdown?

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JDShurak
Starting Member

2 Posts

Posted - 2011-06-24 : 09:52:33
I have a client reporting sluggish performance on the principle server in a mirrored environment.

Running sp_who2 yielded some large cpu times and disk IO times. Here is a link to the screen shot

[url]https://lh3.googleusercontent.com/-YDl9N0NhPys/TgSM1Qa5x-I/AAAAAAAAA90/a9C93Fh7J9Y/mirror.jpg[/url]



The secondary server is seeing a few 'SQL Server has encountered x occurrence(s) of I/O requests taking longer than 15 seconds to complete on file...' x is sometimes in the tens of thousands.

Could these spid's be the culprit? Has anyone encountered anything like this? Is it as simple as killing those processes? Any help would be immensely appreciated. Thanks!

robvolk
Most Valuable Yak

15732 Posts

Posted - 2011-06-24 : 10:25:02
Don't kill the processes, you'll only risk corrupting the mirror and they'll respawn anyway.

If the mirrors are set to high safety (synchronous) mode then there will be a delay on the principal. This is normal. It can be relieved by changing to high performance (asynchronous) mode at the cost of possible data loss under high load.

Are the 2 servers in the same physical location, or geographically separated? Have you checked the network connection between servers?
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JDShurak
Starting Member

2 Posts

Posted - 2011-06-24 : 10:30:29
quote:
Originally posted by robvolk

Don't kill the processes, you'll only risk corrupting the mirror and they'll respawn anyway.

If the mirrors are set to high safety (synchronous) mode then there will be a delay on the principal. This is normal. It can be relieved by changing to high performance (asynchronous) mode at the cost of possible data loss under high load.

Are the 2 servers in the same physical location, or geographically separated? Have you checked the network connection between servers?



Thanks for the reply. Since these are system processes, they can't be killed, so that option is out anyway.

They are currently set to high performance. They are located on the same network, I will check the connection between the two.
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