add documentation for configuring primary storage

admin_manual/configuration_files/index.rst

@@ -14,6 +14,7 @@ File Sharing and Management
     external_storage_configuration_gui
     external_storage_configuration
     external_storage/auth_mechanisms
+    primary_storage
     encryption_configuration
     files_locking_transactional
     previews_configuration

admin_manual/configuration_files/primary_storage.rst

@@ -0,0 +1,70 @@
+===========================
+Primary Storage
+===========================
+
+It's possible to use an object store as primary storage, this replaces the default
+way of storing files in `nextcloud/data` (note that the data directory might still be used
+for other reasons)
+
+---------------------------
+Implications
+---------------------------
+
+When using an object store as primary storage, Nextcloud assumes exclusive access
+over the bucket being used.
+
+Contrary to using an object store as external storage, when an object store is used
+as primary storage, no metadata (names, directory structures, etc) is stored in the
+object store. The metadata is only stored in the database and the object store only
+holds the file content by unique identifier.
+
+Because of this primary object stores usually perform better than when using the same
+object store as external storage but it restricts being able to access the files from
+outside of Nextcloud.
+
+---------------------------
+Configuring
+---------------------------
+
+Primary object stores need to be configured in `config.php` by specifying the objectstore
+backend and any backend specific configuration.
+
+.. note:: Configuring a primary object store on an existing Nextcloud instance will
+	make all existing files on the instance inaccessible.
+
+The configuration has the following structure.
+
+::
+
+	'objectstore' => array(
+		'class' => 'Object\\Storage\\Backend\\Class',
+		'arguments' => array(
+			...
+		),
+	),
+
+--------
+Openstack Swift
+--------
+
+The Swift backend mounts a container on an OpenStack Object Storage server into the virtual filesystem. The class to be used is \\OC\\Files\\ObjectStore\\Swift:
+
+::
+
+	'objectstore' => array(
+		'class' => 'OC\\Files\\ObjectStore\\Swift',
+		'arguments' => array(
+			'username' => 'username',
+			'password' => 'Secr3tPaSSWoRdt7',
+			'container' => 'nextcloud',
+			'autocreate' => true,
+			'region' => 'RegionOne',
+			// The Identity / Keystone endpoint
+			'url' => 'http://example.com/v2.0',
+			// optional on some swift implementations
+			'tenantName' => 'username',
+			'serviceName' => 'swift',
+			// The Interface / url Type, optional
+			'urlType' => 'internal'
+		),
+	),