Wednesday, March 9, 2016

HADR_SYNC_COMMIT wait types in sql server 2012 Always on

Found this recently in our environment:

whenever rebuild index job is running (with online or without), all the application connections are timing out and the wait types show as below
HADR_SYNC_COMMIT

found that this is a bug in Always on  Availability groups when Synchronous mode is used.
To alleviate this, switch to Async mode, do your rebuild indexes and then switch back to Sync mode.

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