SQL Server Log Writer Workers

SQL Server 2017 leverages up to 4 log writer workers, on hidden schedulers, to assist in transaction log processing activities.   You may find the number of log write workers has been increased to 8 when running newer releases of SQL Server to accommodate larger systems.  (Caution: Pre-release software may change before final release.)

During SQL Server startup the number of log writer workers is determined. 

If multiple log write workers are not allowed use a single log writer


  • Total number NUMA nodes * 2
  • Count the number of available CPUs on the NUMA node (affinity mask can impact this count)

       Take the smaller of the above calculations and cap by the MAX_LOG_WRITERS allowed (4 or 8 depending on version)

Bob Dorr

SQL Server 2017 GeneralHow It WorksIt Just Runs FasterNUMAPerformanceScheduler

( No ratings yet )