Files-only installation (Reporting Services)
Applies to: 
SQL Server Reporting Services (2016)
Files-only installation refers to a Reporting Services installation where Setup creates the folder structure for Reporting Services program files, copies the files to disk, registers the Report Server service on the local computer, configures the service account, grants files permissions to the service account, and registers the Reporting Services WMI provider.
A files-only installation includes the following Reporting Services features: Report Server service (which hosts the Report Server Web service and background processing application), Report Builder, the Reporting Services Configuration tool, and the Reporting Services command line utilities (rsconfig.exe, rskeymgmt.exe and rs.exe). It doesn't apply to shared features such as SQL Server Management Studio or SQL Server Data Tools (SSDT), which must be specified as separate items if you want to install them.
In contrast with other installation modes, a report server that is installed in files-only mode isn't operational when Setup is finished. Extra configuration is required to bring the report server online by using the Reporting Services Configuration Manager (Native Mode).
When to select files-only installation mode
A files-only installation must be performed when:
You want to connect the report server to a remote report server database.
You want to install the report server as a named instance.
You have deployment requirements that include using custom settings or functionality, and you want full control over when and how the server is configured.
Installing a SQL Server failover cluster that includes Reporting Services.
How to perform a files-only installation
Files-only installation is the default for Reporting Services.
You can specify a files-only installation through the command line or in the Installation wizard. The following articles provide step-by-step instructions:
Example command line script
For clarity, the example includes /RSINSTALLMODE="FilesOnlyMode". However, because files-only mode is the default, you can omit this argument and still get a files-only mode installation.
setup /q /ACTION=install /FEATURES=RS /InstanceName=MSSQLSERVER /RSSVCACCOUNT="NT AUTHORITY\NETWORK SERVICE" /RSINSTALLMODE="FilesOnlyMode"
Installation wizard
When you select Reporting Services in the Feature Selection page, Setup provides a Reporting Services Configuration page that enables you to specify the installation mode. To specify a files-only installation, select Install but do not configure the report server on the Reporting Services Configuration page.