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This wait type is just as the Books Online entry describes.

(Books Online description: “A background task that processes Windows Server Failover Clustering notifications is waiting for the next notification.  Internal use only.”)

Questions/comments on this wait type? Click here to send Paul an email, especially if you have any information to add to this topic.

Added in SQL Server version:


Removed in SQL Server version:


Extended Events wait_type value:

The map_key value in sys.dm_xe_map_values is 836 in 2012 and 855 in 2014 RTM. After 2014 RTM, you must check the DMV to get the latest value as some map_key values have changed in later builds.

Other information:

I have not seen this wait type be a noticeable contention point.

This wait type is one that I usually filter out as a benign wait when doing wait statistics analysis.

Known occurrences in SQL Server (list number matches call stack list):

  1. Waiting for a failover cluster notification

Abbreviated call stacks (list number matches known occurrences list):

  1. SOS_Task::PostWait+90