Applies to: Exchange Server 2016

This cmdlet is available only in on-premises Exchange Server 2016.

Use the Start-DatabaseAvailabilityGroup cmdlet to reincorporate one or more previously failed members of a database availability group (DAG).

For information about the parameter sets in the Syntax section below, see Syntax.

Start-DatabaseAvailabilityGroup -ActiveDirectorySite <AdSiteIdParameter> -Identity <DatabaseAvailabilityGroupIdParameter> [-ConfigurationOnly <SwitchParameter>] <COMMON PARAMETERS>

Start-DatabaseAvailabilityGroup -Identity <DatabaseAvailabilityGroupIdParameter> -MailboxServer <MailboxServerIdParameter> [-ConfigurationOnly <SwitchParameter>] <COMMON PARAMETERS>

COMMON PARAMETERS: [-Confirm [<SwitchParameter>]] [-DomainController <Fqdn>] [-WhatIf [<SwitchParameter>]]

This example starts the Mailbox server MBX2 in the DAG DAG1.

Start-DatabaseAvailabilityGroup -Identity DAG1 -MailboxServer MBX2

This example starts the members of the DAG DAG1 in the Active Directory site Redmond.

Start-DatabaseAvailabilityGroup -Identity DAG1 -ActiveDirectorySite Redmond

The Start-DatabaseAvailabilityGroup cmdlet is used to activate DAG members in a recovered datacenter after a datacenter switchover, as part of the switchback process to the recovered datacenter. The Start-DatabaseAvailabilityGroup cmdlet manipulates configuration and state so that the servers are incorporated into the operating DAG, and joined to the DAG's underlying cluster. The Move-ActiveMailboxDatabase cmdlet is then used to activate databases in the primary datacenter.

You need to be assigned permissions before you can run this cmdlet. Although all parameters for this cmdlet are listed in this topic, you may not have access to some parameters if they're not included in the permissions assigned to you. To see what permissions you need, see the "Database availability groups" entry in the High availability and site resilience permissions topic.


Parameter Required Type Description




The ActiveDirectorySite parameter specifies whether to start all DAG members in the specified site.




The Identity parameter specifies the name of the DAG being started.




The MailboxServer parameter specifies whether to start a single DAG member.




The ConfigurationOnly switch specifies whether to update the Active Directory properties with the start action, but doesn't perform a start of the DAG or any members.




The Confirm switch specifies whether to show or hide the confirmation prompt. How this switch affects the cmdlet depends on if the cmdlet requires confirmation before proceeding.

  • Destructive cmdlets (for example, Remove-* cmdlets) have a built-in pause that forces you to acknowledge the command before proceeding. For these cmdlets, you can skip the confirmation prompt by using this exact syntax: -Confirm:$false.

  • Most other cmdlets (for example, New-* and Set-* cmdlets) don't have a built-in pause. For these cmdlets, specifying the Confirm switch without a value introduces a pause that forces you acknowledge the command before proceeding.




The DomainController parameter specifies the domain controller that's used by this cmdlet to read data from or write data to Active Directory. You identify the domain controller by its fully qualified domain name (FQDN). For example,




The WhatIf switch simulates the actions of the command. You can use this switch to view the changes that would occur without actually applying those changes. You don't need to specify a value with this switch.

To see the input types that this cmdlet accepts, see Cmdlet Input and Output Types. If the Input Type field for a cmdlet is blank, the cmdlet doesn’t accept input data.

To see the return types, which are also known as output types, that this cmdlet accepts, see Cmdlet Input and Output Types. If the Output Type field is blank, the cmdlet doesn’t return data.