SQL Alert Anomaly

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SQL Alert Anomaly

planetmatt

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November 3, 2008 at 8:44 am

#127345

I have an alert set up on a Live and Staging server. The alert fires when the Buffer Cache Hit Ratio falls below 80%.
Since the weekend, this alert is firing constantly on both servers. The problem is, when viewing this counter in Performance Monitor, it never falls below 99.8%. I have tried dropping and recreating the Alert but it still keeps firing. I also tried dropping the threshold to 50% and still it keeps firing.
From speaking to the Infrastructure team, the only thing that has changed is that they applied the http://support.microsoft.com/kb/954607 security hotfix over the weekend.
I can't find anything on the web connecting this issue to the hotfix but if anyone else is experiencing this or knows why there is a discrepancy between the alert and the perfmon graph, please let me know.
Cheers
Matt

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SQLZ SSChampion Points: 12872 More actions · Answer 1

Are you sure you're looking at the right counter in perfmon and that you're alerting on the right counter?

There's the SQLServer:CacheManager\Cache Hit Ratio and the SQLServer:BufferManager\Buffer Cache hit ratio?

Karl
source control for SQL Server

mritley SSC Rookie Points: 40 More actions · Answer 2

I am having the same problem after the 954607 patch was applied.

We are on a sqlcluster.

-Maris

planetmatt SSCrazy Points: 2201 More actions · Answer 3

SQLZ (11/3/2008)
Are you sure you're looking at the right counter in perfmon and that you're alerting on the right counter?
There's the SQLServer:CacheManager\Cache Hit Ratio and the SQLServer:BufferManager\Buffer Cache hit ratio?

My alert and perfmon are both looking at SQLServer:BufferManager\Buffer Cache hit ratio.

G.R.Prithiviraj Kulasingham SSCarpal Tunnel Points: 4105 More actions · Answer 4

I too am facing the same problem. I installed sp3 on this server. I received an interesting description

DATE/TIME:1/17/2009 7:42:12 PM

DESCRIPTION:The SQL Server performance counter 'Buffer cache hit ratio' (instance 'N/A') of object 'MSSQL$I02:Buffer Manager' is now below the threshold of 99.00 (the current value is 1.00).

COMMENT:(None)

JOB RUN:(None)

The performance counter is not below 99.8, and I have set the mail to fire only when the figure goes below 99.

I changed it to run when hit ration raise above 1, but it never sent an alert . :w00t:

Cheers,
Prithiviraj Kulasingham

http://preethiviraj.blogspot.com/