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We recently migrated a large chunk of our databases to a new data center and on one of our clusters we are now seeing high amounts of waits for HADR_SYNCHRONIZING_THROTTLE. We didn't see this in our previous data center.

The only thing I have noticed since the migration are errors related to Change Tracking that is enabled on two of the databases. These errors look like:

Error: 77735, Severity: 16, State: 1. Change Tracking cleanup job is running in DB1 for 1475 minutes more than the threshold(24hrs); DB2 for 3379 minutes more than the threshold(24hrs)

It looks like I'll have to disable and re-enable CT to clear this message so possibly this might be what is causing the waits mentioned.

Has anyone seen HADR_SYNCHRONIZING_THROTTLE waits before and got to the bottom of why they are appearing?

In terms of our environment we are currently running SQL Server 2012 11.0.7462.6.

Thanks in advance.

  • 1
    Are the databases in environments with different resources from one another? I ask because you can see in the Types of Waits that "This is an expected wait when a secondary database is catching up." – Ronaldo Oct 15 at 23:13
  • The only difference is the newer hardware on the servers in the new data center. All four nodes in the cluster have the same hardware. – bn25 Oct 16 at 3:39
  • is Change tracking working ? any other replication, etc ? Try looking into Trace Flag 1448 - as CT uses a log reader thread and what you are seeing is just a symptom of something causing it. – Kin Shah Oct 16 at 12:41

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