- Except for credentials information, the synchronization configuration stored in the ADSync database is automatically recovered and used during installation. This includes custom synchronization rules, connectors, filtering, and optional features configuration.
- All the identity data (associated with connector spaces and metaverse) and synchronization cookies stored in the ADSync database are also recovered. The newly installed Microsoft Entra Connect server can continue to synchronize from where the previous Microsoft Entra Connect server left off, instead of having the need to perform a full sync.
## Scenarios where using an existing ADSync database is beneficial
These benefits are useful in the following scenarios:
## Steps to install Microsoft Entra Connect with βuse existing databaseβ mode
1. Download Microsoft Entra Connect installer (AzureADConnect.MSI) to the Windows server. Double-select the Microsoft Entra Connect installer to start installing Microsoft Entra Connect.
2. Once the MSI installation completes, the Microsoft Entra Connect wizard starts with the Express mode setup. Close the screen by selecting the Exit icon.

3. Start a new command prompt or PowerShell session. Navigate to folder "C:\Program Files\Microsoft Azure Active Directory Connect". Run command .\AzureADConnect.exe /useexistingdatabase to start the Microsoft Entra Connect wizard in βUse existing databaseβ setup mode.

1. You are greeted with the Welcome to Microsoft Entra Connect screen. Once you agree to the license terms and privacy notice, select **Continue**.

1. On the **Install required components** screen, the **Use an existing SQL Server** option is enabled. Specify the name of the SQL server that is hosting the ADSync database. If the SQL engine instance used to host the ADSync database isn't the default instance on the SQL server, you must specify the SQL engine instance name. Further, if SQL browsing isn't enabled, you must also specify the SQL engine instance port number. For example:

- Except for credentials information, the synchronization configuration stored in the ADSync database is automatically recovered and used during installation. This includes custom synchronization rules, connectors, filtering, and optional features configuration.
- All the identity data (associated with connector spaces and metaverse) and synchronization cookies stored in the ADSync database are also recovered. The newly installed Microsoft Entra Connect server can continue to synchronize from where the previous Microsoft Entra Connect server left off, instead of having the need to perform a full sync.
> [!IMPORTANT]
> In certain edge cases, installing from an existing ADSync database may trigger a full synchronization cycle. If you're not ready to initiate a full sync immediately after installation, you can defer it by configuring the sync scheduler. Use one of the following options:
- To set the NextSyncCyclePolicyType: `Set-ADSyncScheduler -NextSyncCyclePolicyType Delta`
> - To override connector behavior and prevent a full import/sync: `Set-ADSyncSchedulerConnectorOverride -ConnectorName '<connector name>' -FullImportRequired $false -FullSyncRequired $false`
## Scenarios where using an existing ADSync database is beneficial
These benefits are useful in the following scenarios:
## Steps to install Microsoft Entra Connect with βuse existing databaseβ mode
1. Download Microsoft Entra Connect installer (AzureADConnect.MSI) to the Windows server. Double-select the Microsoft Entra Connect installer to start installing Microsoft Entra Connect.
1. Once the MSI installation completes, the Microsoft Entra Connect wizard starts with the Express mode setup. Close the screen by selecting the Exit icon.

3. Start a new command prompt or PowerShell session. Navigate to folder "C:\Program Files\Microsoft Azure Active Directory Connect". Run command .\AzureADConnect.exe /useexistingdatabase to start the Microsoft Entra Connect wizard in βUse existing databaseβ setup mode.
