On all our AlwaysOn setups, running Windows 2012 and SQL Server 2012 in virtual machines and on bare-metal, I find that the log_send_rate in
sys.dm_hadr_database_replica_states
is consistently returning incorrect values.
For example (for synchronous mode)
sys.dm_hadr_database_replica_states.log_send_rate (ave = 36,571 (kb/s listed in bol))
Perfmon – SQLServer:Availability Replica – Bytes Sent to Replica/sec (max = 486,000.000, avg = 259,000.000)
Perfmon – SQLServer:Databases – Log Bytes Flushed/sec (max = 653,044.000, avg = 341,000.000)
I've not seen any posts about this but it doesn't appear to be working correctly. A correct log_send_rate
value is useful for monitoring AlwaysOn.
Has anyone else experienced this?
Best Answer
Yes, this was fixed recently in Service Pack 2, Cumulative Update 3. Here's the KB article: http://support.microsoft.com/kb/3012182
"FIX: Log_Send_Rate column in sys.dm_hadr_database_replica_states cannot reflect the rate accurately in SQL Server 2012"