SQL Server, Database Replica

APPLIES TO: yesSQL Server noAzure SQL Database noAzure SQL Data Warehouse noParallel Data Warehouse

The SQLServer:Database Replica performance object contains performance counters that report information about the secondary databases of an Always On availability group in SQL Server 2017. This object is valid only on an instance of SQL Server that hosts a secondary replica.

Counter Name Description View on...
File Bytes Received/sec Amount of FILESTREAM data received by the secondary replica for the secondary database in the last second. Secondary replica
Log Apply Pending Queue Number of log blocks that are waiting to be applied to the database replica. Secondary replica
Log Apply Ready Queue Number of log blocks that are waiting and ready to be applied to the database replica. Secondary replica
Log Bytes Received/sec Amount of log records received by the secondary replica for the database in the last second. Secondary replica
Log remaining for undo The amount of log, in kilobytes, remaining to complete the undo phase. Secondary replica
Log Send Queue Amount of log records in the log files of the primary database, in kilobytes, that haven't been sent to the secondary replica. This value is sent to the secondary replica from the primary replica. Queue size doesn't include FILESTREAM files that are sent to a secondary. Secondary replica
Mirrored Write Transaction/sec Number of transactions that were written to the primary database and then waited to commit until the log was sent to the secondary database, in the last second. Primary replica
Recovery Queue Amount of log records in the log files of the secondary replica that have not been redone. Secondary replica
Redo blocked/sec Number of times the redo thread was blocked on locks held by readers of the database. Secondary replica
Redo Bytes Remaining The amount of log, in kilobytes, remaining to be redone to finish the reverting phase. Secondary replica
Redone Bytes/sec Amount of log records redone on the secondary database in the last second. Secondary replica
Total Log requiring undo Total kilobytes of log that must be undone. Secondary replica
Transaction Delay Delay in waiting for unterminated commit acknowledgment for all the current transactions, in milliseconds. Divide by Mirrored Write Transaction/sec to get Avg Transaction Delay. For more information, see SQL Server 2012 AlwaysOn – Part 12 – Performance Aspects and Performance Monitoring II Primary replica

See Also

Monitor Resource Usage (System Monitor)
SQL Server, Availability Replica
SQL Server, Databases Object
Always On Availability Groups (SQL Server)