Discrepancy Between sys.dm_os_performance_counters and DBCC SQLPERF(logspace)

  • Background -

    A deployment gone bad. Deployment caused the transaction log to grow to the point where I needed to add a 2nd one. Deployment is done, and now I am cleaning up. I am getting alerts that my TLog is over it's threshold, but it is not. When I run DBCC SQLPERF(loginfo), it shows my log as ~8.5 GB. When I look at the actual file on disk, it also shows 8.5 GB. This is what I expect.

    The issue is that the alert is being generated from:

    select * from sys.dm_os_performance_counters

    where object_name = 'SQLServer:Databases'

    and instance_name = ...

    and counter_name = 'Log File(s) Size (KB)'

    This tells me that the log file is 18.5 GB. When I run system monitor I see the same result.

    The log file that I added, and deleted after the fact was 10 GB. PerMon thinks it is still there. I have verified from the file system that there is no file there anymore.

    Has anyone seen a similar discrepancy, or can anyone explain to me why I might be seeing this? Thanks in advance.

  • Not 100%, but some sys views only refresh on a SQL restart - could be that the extraneous counter will vanish then.

  • have you run a log backup since removing the extra log file?

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    "Ya can't make an omelette without breaking just a few eggs" 😉

  • Perry Whittle (12/11/2012)


    have you run a log backup since removing the extra log file?

    Yup - we run them every 10 minutes, for log shipping.

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