sql-server-database-replica.md

title	SQL Server, Database Replica | Microsoft Docs
description	Learn about the SQLServer:Database Replica performance object, which contains performance counters about secondary databases of an Always On availability group.
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ms.date	08/24/2016
ms.prod	sql
ms.prod_service	database-engine
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ms.technology	performance
ms.topic	conceptual
helpviewer_keywords	Availability Groups [SQL Server], monitoring SQLServer:Database Replica performance counters [SQL Server], AlwaysOn Availability Groups Availability Groups [SQL Server], performance counters
ms.assetid	a5f6bdce-2b13-4924-aaeb-b50b57d624d8
author	julieMSFT
ms.author	jrasnick

SQL Server, Database Replica

[!INCLUDE SQL Server] The SQLServer:Database Replica performance object contains performance counters that report information about the secondary databases of an Always On availability group in [!INCLUDEssCurrent]. This object is valid only on an instance of [!INCLUDEssNoVersion] 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)