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This wait type is when a thread switches to preemptive mode as part of renewing the lease between the failover cluster and the SQL Server resource DLL because of a lease timeout. The lease is essentially a health check mechanism, and a timeout indicates there is a problem with the availability group.
(Books Online description: “Always On Availability Groups lease manager scheduling for CSS diagnostics.”)
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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 862 in 2012 and 881 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.
Here are some links to help with troubleshooting the problems that could cause a lease timeout, leading to this wait type occurring:
- Improved AlwaysOn Availability Group Lease Timeout Diagnostics
- Diagnose Unexpected Failover or Availability Group in RESOLVING State
Anecdotal evidence indicates that network problems seem to be the major cause of lease timeouts.
Known occurrences in SQL Server (list number matches call stack list):
Abbreviated call stacks (list number matches known occurrences list):