The replay queue length on passive copies of mailbox databases in Database Availability Group continues to increase in an Exchange Server 2010 environment

Symptoms

In a Microsoft Exchange Server 2010 environment, the replay queue length on passive copies of mailbox databases in Database Availability Group (DAG) may continue to increase. The log files are copied to the passive copies of the mailbox databases successfully. However, the log files are not replayed into the mailbox databases. Additionally, when the Microsoft Exchange Replication service starts, the following event is logged in the Application log:

Cause

This issue occurs when the mailbox databases have the "Don't mount this database at startup" check box selected. In this situation, Extensible Storage Engine cannot attach to the databases to replay the logs. 

Resolution

To resolve this issue, install the following update rollup:

2425179 Description of Update Rollup 2 for Exchange Server 2010 Service Pack 1

Workaround

To work around this issue, clear the "Don't mount this database at startup" check box from the databases properties. To do this, use one of the following methods.

• Method 1: To perform this operation in the Exchange Management Console, follow these steps:

  1. In the Exchange Management Console, expand Organization Configuration and then expand Mailbox.

  2. Select and then right-click the database.

  3. Click Properties and then click the Maintenance tab.

  4. Clear the "Don't mount this database at startup" check box.

  5. Click Apply and then click OK.

  6. Restart the Microsoft Exchange Replication service.

  
  

• Method 2: To perform this operation in the Exchange Management Shell, follow these steps:

  1. Run the following command in the Exchange Management Shell:

     Set-MailboxDatabase -identity "<Mailbox Database Name>" -MountAtStartup $True

  2. Restart the Microsoft Exchange Replication service.

More Information

To find which databases have the "Don't mount this database at startup" check box set, use the following command in the Exchange Management Shell:

Get-Mailboxdatabase | where { $_.mountatstartup -like "False" }

To clear this check box for all these databases, use the following command in the Exchange Management Shell:

Get-Mailboxdatabase | where { $_.mountatstartup -like "False" } | Set-MailboxDatabase -MountAtStartup $True