The HADR_LOGCAPTURE_WAIT and HADR_WORK_QUEUE are waits related to AlwaysOn Availability Group. The AlwaysOn Availability Group concept was introduced in SQL Server 2012. It was introduced to replace database mirroring. The AlwaysOn wait types can be easily recognized by the HADR_ prefix. We will be looking into the HADR_LOGCAPTURE_WAIT and HADR_WORKQUEUE waits in detail.
What are the HADR_LOGCAPTURE_WAIT and HADR_WORK_QUEUE wait types?
The HADR_LOGCAPTURE_WAIT and HADR_WORK_QUEUE wait types are benign and occur naturally within the AlwaysOn configuration.
HADR_LOGCAPTURE_WAIT
HADR_LOGCAPTURE_WAIT
occurs when waiting for the log records to be available. We can encounter this wait type when new log records are generated by connections. Additionally,
the wait type can be expected when the log scan is read from the disk. HADR_LOGCAPTURE_WAIT
occurs in the primary database inside the AlwaysOn Availability Group.
HADR_WORK_QUEUE
The HADR_WORK_QUEUE
wait type occurs when the AlwaysOn Availability Group is waiting for a new worker
thread to be assigned. This is an expected action by the AlwaysOn functionality.
Additionally, the wait type is an indication of free threads waiting for work.
Sys.dm_os_wait_stats
You can
check the HADR_LOGCAPTURE_WAIT and HARD_WORK_QUEUE wait type information from
the DMV – sys.dm_os_wait_stats.
Bottomline
Both
HADR_LOGCAPTURE_WAIT and HARD_WORK_QUEUE wait types are good. They are natural
to encounter if we have the AlwaysOn enabled servers. Having these wait types
does not indicate a performance overhead. There is no attention needed in case
you see these wait types.
More Wait Types For your reference:
What is REDO_THREAD_PENDING_WORK Wait Type?
What is HADR_SYNC_COMMIT Wait Type?
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