17 March,2014 by Tom Collins

Step 1 : In the SQL Server context ,  Preemptive  means priority. In other words, a higher priority task will interrupt (preempt) a lower priority SQL Server task and takeover the Quantum to allow running on CPU. When the higher priority Windows task completes , the lower priority SQL Server task continues executing the task  on the CPU.

Step 2 : A good piece of advice on this blog   is to use the suffix as a clue for the PREEMPTIVE wait types . The MSDN docs  defines theThe LookupAccountSid function as  accepting a security identifier (SID) as input. It retrieves the name of the account for this SID and the name of the first domain on which this SID is found

Combining Step 1 and Step 2 leads us to consider what sort of activity could preempt a SQL Server task and how do we go about troubleshooting this wait type.

Based on this information areas of investigation include:

1) Have you checked that the DNS/AD settings are correct.

2) Is the SQL Server use current and relevant DNS server reference?

3) The function suser _sname function returns the login name associated with a SID. The SID  is checked against the Active Directory. Running these two queries – highlights any Active Directory responsiveness issues. It is possible the SUSER_SNAME function may respond slowly.If so, start an investigation

SELECT sid FROM sys.database_principals  
SELECT SUSER_SNAME(sid) FROM sys.database_principals 

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Author: Tom Collins (


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