Performance troubleshooting

  • We have a department who has a couple of SQL servers,they said there sometimes maybe disk I/O issues. That is all information I got from them. They would like me to help troubleshooting.

    How can I help them to identify the problem using SQL server native tools.

    I login to the server and found it has 24 GB memory and max memory set to 20 GB.

    What information I need from them to start troubleshooting?

    Currently it runs fine.

    PS: I know I can use PM, DMV, or any other recommendations to start with?

    I think I have to set up real time monitor, otherwise it will collect too many data to save somewhere, or shall I first ask them when the slowness usually happen to monitor a certain time period?

    Thanks,

  • Disk IO? How they confirm this. Do they have any IO related error in event log ? .

    select * from sys.dm_io_virtual_file_stats (Null,null)

    Run the query to see any IO stalls (IO_stalls_read_ms and IO_stalls_write_ms) are

    there (considerable IO stall for considerable duration)

    You may run Performance Monitor.exe to find disk IO metrics.See for "Disk Queue Length".

  • Also look at sys.dm_os_wait_stats. That's going to tell you specifically what is causing things to slow down on the server. It won't narrow it down to particular processes or anything, but you'll know if it's I/O, memory, CPU or whatever.

    "The credit belongs to the man who is actually in the arena, whose face is marred by dust and sweat and blood"
    - Theodore Roosevelt

    Author of:
    SQL Server Execution Plans
    SQL Server Query Performance Tuning

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