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This wait type is where a thread is calling various failover cluster APIs to get information back from the cluster, and the majority of the calls related to getting drive properties.

(Books Online description: “Occurs when the SQLOS scheduler switches to preemptive mode to perform Windows failover cluster operations.”)

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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 385 in 2008 and 2008 R2, 433 in 2012, and 449 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:

This wait type commonly occurs when there is latency accessing drives being used as cluster resources. Check the disk response time for those drives, and whether there is a network delay communicating with those resources.

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

  1. TBD

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

  1. TBD