This alert indicates that a replication issue may affect the mailbox database copies in a particular Microsoft Exchange Server 2010 database availability group (DAG).

Exchange 2010 uses continuous replication to create and maintain database copies. To maintain a synchronized copy of a mailbox database, transaction log files from the active mailbox server are replayed into the passive database of another server in the DAG. This provides high availability and resiliency in the Exchange environment.

The information store is responsible for replaying the log file for the passive copy of the database that is hosted on a server. When a replica instance of a copied database is started, the Replay service contacts the information store and creates an ESE instance for the database to be mounted. This mount is for log replay only. The Replay service Log Replayer component then contacts the store over the RPC STORE ADMIN Interface (ExRpcAdmin.LogReplayRequest) to pass the log files that have to be replayed by the store.

If the transaction log replay operations cannot keep up with the changes that are made to the active mailbox server database, the database copies will not be up-to-date. Therefore, it may take longer to bring a replica copy online if a problem is affecting the active mailbox database.

A warning (Yellow) alert is generated when the Reliability and Performance monitor MSExchange Replication object has a value greater than 1. If the object's value is greater than 1 over a two-hour period, a severe problem (Red) alert is generated.

To resolve this error, do one or more of the following:

• Review the Application log and System log on your Exchange 2010 servers for related events. For example, events that occur immediately before and after this event may provide more information about the root cause of this error.
  
  
• Review the Operations Console in Operations Manager for detailed information about the cause of this problem. For more information, see the "Introduction" section in this article.
  
  
• Check the following performance counter by using Windows Reliability and Performance Monitor:
  
  
  • Object: MSExchange Replication
    
    
• Examine the network topology between the active and passive database copies. Database copies are not supported between Mailbox servers that have round-trip network latency greater than 250 milliseconds (ms).
  
  
• Examine the CPU usage for the Information Store service on the passive mailbox server.
  
  
• Examine the current replication status for each replica database. To do this, use the Get-MailboxDatabaseCopyStatus cmdlet. This cmdlet returns information about all copies of a particular database, information about a specific copy of a database on a specific server, or information about all database copies on a server.
  
  

For more information, see the following topics in Exchange 2010 Help:

• Understanding Mailbox Database Copies
  
  
• Understanding Database Availability Groups
  
  

If you are not already doing so, consider running the Exchange tools created to help you analyze and troubleshoot your Exchange environment. These tools can help make sure that your configuration aligns with Microsoft best practices. They can also help you identify and resolve performance issues, improve mail flow, and better manage disaster recovery scenarios. To run these tools, go to the Toolbox node of the Exchange Management Console. To learn more about these tools, see Managing Tools in the Toolbox.