diff --git a/apps/files_external/lib/Lib/Storage/AmazonS3.php b/apps/files_external/lib/Lib/Storage/AmazonS3.php
index 6fdb43d564f0..09982bf3877d 100644
--- a/apps/files_external/lib/Lib/Storage/AmazonS3.php
+++ b/apps/files_external/lib/Lib/Storage/AmazonS3.php
@@ -43,7 +43,7 @@
 use Aws\S3\Exception\S3Exception;
 use Icewind\Streams\IteratorDirectory;
 
-class AmazonS3 extends \OC\Files\Storage\Common {
+class AmazonS3 extends \OCP\Files\Storage\StorageAdapter {
 
 	/**
 	 * @var \Aws\S3\S3Client
diff --git a/apps/files_external/lib/Lib/Storage/Dropbox.php b/apps/files_external/lib/Lib/Storage/Dropbox.php
index 5da8d88b005b..1d032b9cbec5 100644
--- a/apps/files_external/lib/Lib/Storage/Dropbox.php
+++ b/apps/files_external/lib/Lib/Storage/Dropbox.php
@@ -36,7 +36,7 @@
 
 require_once __DIR__ . '/../../../3rdparty/Dropbox/autoload.php';
 
-class Dropbox extends \OC\Files\Storage\Common {
+class Dropbox extends \OCP\Files\Storage\StorageAdapter {
 
 	private $dropbox;
 	private $root;
diff --git a/apps/files_external/lib/Lib/Storage/Google.php b/apps/files_external/lib/Lib/Storage/Google.php
index 7907bf60fae7..37f28b2e3bd3 100644
--- a/apps/files_external/lib/Lib/Storage/Google.php
+++ b/apps/files_external/lib/Lib/Storage/Google.php
@@ -42,7 +42,7 @@
 	\OC_App::getAppPath('files_external').'/3rdparty/google-api-php-client/src');
 require_once 'Google/autoload.php';
 
-class Google extends \OC\Files\Storage\Common {
+class Google extends \OCP\Files\Storage\StorageAdapter {
 
 	private $client;
 	private $id;
diff --git a/apps/files_external/lib/Lib/Storage/SFTP.php b/apps/files_external/lib/Lib/Storage/SFTP.php
index b8c339893689..2dfc3d5c5f2d 100644
--- a/apps/files_external/lib/Lib/Storage/SFTP.php
+++ b/apps/files_external/lib/Lib/Storage/SFTP.php
@@ -40,7 +40,7 @@
 * Uses phpseclib's Net\SFTP class and the Net\SFTP\Stream stream wrapper to
 * provide access to SFTP servers.
 */
-class SFTP extends \OC\Files\Storage\Common {
+class SFTP extends \OCP\Files\Storage\StorageAdapter {
 	private $host;
 	private $user;
 	private $root;
diff --git a/apps/files_external/lib/Lib/Storage/SMB.php b/apps/files_external/lib/Lib/Storage/SMB.php
index 19d5b499e284..49ac8c86ed60 100644
--- a/apps/files_external/lib/Lib/Storage/SMB.php
+++ b/apps/files_external/lib/Lib/Storage/SMB.php
@@ -43,11 +43,10 @@
 use Icewind\Streams\IteratorDirectory;
 use OC\Cache\CappedMemoryCache;
 use OC\Files\Filesystem;
-use OC\Files\Storage\Common;
 use OCP\Files\StorageNotAvailableException;
 use OCP\Util;
 
-class SMB extends Common {
+class SMB extends \OCP\Files\Storage\StorageAdapter {
 	/**
 	 * @var \Icewind\SMB\Server
 	 */
diff --git a/apps/files_external/lib/Lib/Storage/StreamWrapper.php b/apps/files_external/lib/Lib/Storage/StreamWrapper.php
index 910c85247965..ffd4a8fd3afb 100644
--- a/apps/files_external/lib/Lib/Storage/StreamWrapper.php
+++ b/apps/files_external/lib/Lib/Storage/StreamWrapper.php
@@ -27,7 +27,7 @@
 
 namespace OCA\Files_External\Lib\Storage;
 
-abstract class StreamWrapper extends \OC\Files\Storage\Common {
+abstract class StreamWrapper extends \OCP\Files\Storage\StorageAdapter {
 
 	/**
 	 * @param string $path
diff --git a/apps/files_external/lib/Lib/Storage/Swift.php b/apps/files_external/lib/Lib/Storage/Swift.php
index 35da3b13618b..2924d8bda7c6 100644
--- a/apps/files_external/lib/Lib/Storage/Swift.php
+++ b/apps/files_external/lib/Lib/Storage/Swift.php
@@ -44,7 +44,7 @@
 use OpenCloud\ObjectStore\Resource\DataObject;
 use OpenCloud\ObjectStore\Exception;
 
-class Swift extends \OC\Files\Storage\Common {
+class Swift extends \OCP\Files\Storage\StorageAdapter {
 
 	/**
 	 * @var \OpenCloud\ObjectStore\Service
diff --git a/lib/public/Files/Storage/FlysystemStorageAdapter.php b/lib/public/Files/Storage/FlysystemStorageAdapter.php
new file mode 100644
index 000000000000..1b82682d24f5
--- /dev/null
+++ b/lib/public/Files/Storage/FlysystemStorageAdapter.php
@@ -0,0 +1,41 @@
+<?php
+/**
+ * @author Vincent Petry <pvince81@owncloud.com>
+ *
+ * @copyright Copyright (c) 2016, ownCloud GmbH.
+ * @license AGPL-3.0
+ *
+ * This code is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License, version 3,
+ * as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License, version 3,
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>
+ *
+ */
+
+namespace OCP\Files\Storage;
+
+/**
+ * Public storage adapter to be extended to connect to
+ * flysystem adapters
+ *
+ * @since 9.2
+ */
+abstract class FlysystemStorageAdapter extends \OC\Files\Storage\Flysystem {
+
+	/**
+	 * Get the identifier for the storage,
+	 * the returned id should be the same for every storage object that is created with the same parameters
+	 * and two storage objects with the same id should refer to two storages that display the same files.
+	 *
+	 * @return string storage id
+	 * @since 9.2
+	 */
+	abstract public function getId();
+}
diff --git a/lib/public/Files/Storage/IStorage.php b/lib/public/Files/Storage/IStorage.php
index e2272c48fe14..8311f051fab5 100644
--- a/lib/public/Files/Storage/IStorage.php
+++ b/lib/public/Files/Storage/IStorage.php
@@ -34,6 +34,7 @@
 use OCP\Files\Cache\IUpdater;
 use OCP\Files\Cache\IWatcher;
 use OCP\Files\InvalidPathException;
+use OCP\Files\StorageNotAvailableException;
 
 /**
  * Provide a common interface to all different storage options
@@ -56,7 +57,7 @@ public function __construct($parameters);
 	 * the returned id should be the same for every storage object that is created with the same parameters
 	 * and two storage objects with the same id should refer to two storages that display the same files.
 	 *
-	 * @return string
+	 * @return string storage id
 	 * @since 9.0.0
 	 */
 	public function getId();
@@ -66,7 +67,8 @@ public function getId();
 	 * implementations need to implement a recursive mkdir
 	 *
 	 * @param string $path
-	 * @return bool
+	 * @return bool true on success, false otherwise
+	 * @throws StorageNotAvailableException if the storage is temporarily not available
 	 * @since 9.0.0
 	 */
 	public function mkdir($path);
@@ -75,7 +77,8 @@ public function mkdir($path);
 	 * see http://php.net/manual/en/function.rmdir.php
 	 *
 	 * @param string $path
-	 * @return bool
+	 * @return bool true on success, false otherwise
+	 * @throws StorageNotAvailableException if the storage is temporarily not available
 	 * @since 9.0.0
 	 */
 	public function rmdir($path);
@@ -85,6 +88,7 @@ public function rmdir($path);
 	 *
 	 * @param string $path
 	 * @return resource|false
+	 * @throws StorageNotAvailableException if the storage is temporarily not available
 	 * @since 9.0.0
 	 */
 	public function opendir($path);
@@ -94,6 +98,7 @@ public function opendir($path);
 	 *
 	 * @param string $path
 	 * @return bool
+	 * @throws StorageNotAvailableException if the storage is temporarily not available
 	 * @since 9.0.0
 	 */
 	public function is_dir($path);
@@ -103,6 +108,7 @@ public function is_dir($path);
 	 *
 	 * @param string $path
 	 * @return bool
+	 * @throws StorageNotAvailableException if the storage is temporarily not available
 	 * @since 9.0.0
 	 */
 	public function is_file($path);
@@ -113,6 +119,7 @@ public function is_file($path);
 	 *
 	 * @param string $path
 	 * @return array|false
+	 * @throws StorageNotAvailableException if the storage is temporarily not available
 	 * @since 9.0.0
 	 */
 	public function stat($path);
@@ -122,6 +129,7 @@ public function stat($path);
 	 *
 	 * @param string $path
 	 * @return string|false
+	 * @throws StorageNotAvailableException if the storage is temporarily not available
 	 * @since 9.0.0
 	 */
 	public function filetype($path);
@@ -132,6 +140,7 @@ public function filetype($path);
 	 *
 	 * @param string $path
 	 * @return int|false
+	 * @throws StorageNotAvailableException if the storage is temporarily not available
 	 * @since 9.0.0
 	 */
 	public function filesize($path);
@@ -141,6 +150,7 @@ public function filesize($path);
 	 *
 	 * @param string $path
 	 * @return bool
+	 * @throws StorageNotAvailableException if the storage is temporarily not available
 	 * @since 9.0.0
 	 */
 	public function isCreatable($path);
@@ -150,6 +160,7 @@ public function isCreatable($path);
 	 *
 	 * @param string $path
 	 * @return bool
+	 * @throws StorageNotAvailableException if the storage is temporarily not available
 	 * @since 9.0.0
 	 */
 	public function isReadable($path);
@@ -159,6 +170,7 @@ public function isReadable($path);
 	 *
 	 * @param string $path
 	 * @return bool
+	 * @throws StorageNotAvailableException if the storage is temporarily not available
 	 * @since 9.0.0
 	 */
 	public function isUpdatable($path);
@@ -168,6 +180,7 @@ public function isUpdatable($path);
 	 *
 	 * @param string $path
 	 * @return bool
+	 * @throws StorageNotAvailableException if the storage is temporarily not available
 	 * @since 9.0.0
 	 */
 	public function isDeletable($path);
@@ -177,6 +190,7 @@ public function isDeletable($path);
 	 *
 	 * @param string $path
 	 * @return bool
+	 * @throws StorageNotAvailableException if the storage is temporarily not available
 	 * @since 9.0.0
 	 */
 	public function isSharable($path);
@@ -187,6 +201,7 @@ public function isSharable($path);
 	 *
 	 * @param string $path
 	 * @return int
+	 * @throws StorageNotAvailableException if the storage is temporarily not available
 	 * @since 9.0.0
 	 */
 	public function getPermissions($path);
@@ -196,6 +211,7 @@ public function getPermissions($path);
 	 *
 	 * @param string $path
 	 * @return bool
+	 * @throws StorageNotAvailableException if the storage is temporarily not available
 	 * @since 9.0.0
 	 */
 	public function file_exists($path);
@@ -205,6 +221,7 @@ public function file_exists($path);
 	 *
 	 * @param string $path
 	 * @return int|false
+	 * @throws StorageNotAvailableException if the storage is temporarily not available
 	 * @since 9.0.0
 	 */
 	public function filemtime($path);
@@ -214,6 +231,7 @@ public function filemtime($path);
 	 *
 	 * @param string $path
 	 * @return string|false
+	 * @throws StorageNotAvailableException if the storage is temporarily not available
 	 * @since 9.0.0
 	 */
 	public function file_get_contents($path);
@@ -224,6 +242,7 @@ public function file_get_contents($path);
 	 * @param string $path
 	 * @param string $data
 	 * @return bool
+	 * @throws StorageNotAvailableException if the storage is temporarily not available
 	 * @since 9.0.0
 	 */
 	public function file_put_contents($path, $data);
@@ -232,7 +251,8 @@ public function file_put_contents($path, $data);
 	 * see http://php.net/manual/en/function.unlink.php
 	 *
 	 * @param string $path
-	 * @return bool
+	 * @return bool true on success, false otherwise
+	 * @throws StorageNotAvailableException if the storage is temporarily not available
 	 * @since 9.0.0
 	 */
 	public function unlink($path);
@@ -243,6 +263,7 @@ public function unlink($path);
 	 * @param string $path1
 	 * @param string $path2
 	 * @return bool
+	 * @throws StorageNotAvailableException if the storage is temporarily not available
 	 * @since 9.0.0
 	 */
 	public function rename($path1, $path2);
@@ -253,6 +274,7 @@ public function rename($path1, $path2);
 	 * @param string $path1
 	 * @param string $path2
 	 * @return bool
+	 * @throws StorageNotAvailableException if the storage is temporarily not available
 	 * @since 9.0.0
 	 */
 	public function copy($path1, $path2);
@@ -263,6 +285,7 @@ public function copy($path1, $path2);
 	 * @param string $path
 	 * @param string $mode
 	 * @return resource|false
+	 * @throws StorageNotAvailableException if the storage is temporarily not available
 	 * @since 9.0.0
 	 */
 	public function fopen($path, $mode);
@@ -273,6 +296,7 @@ public function fopen($path, $mode);
 	 *
 	 * @param string $path
 	 * @return string|false
+	 * @throws StorageNotAvailableException if the storage is temporarily not available
 	 * @since 9.0.0
 	 */
 	public function getMimeType($path);
@@ -284,6 +308,7 @@ public function getMimeType($path);
 	 * @param string $path
 	 * @param bool $raw
 	 * @return string|false
+	 * @throws StorageNotAvailableException if the storage is temporarily not available
 	 * @since 9.0.0
 	 */
 	public function hash($type, $path, $raw = false);
@@ -293,6 +318,7 @@ public function hash($type, $path, $raw = false);
 	 *
 	 * @param string $path
 	 * @return int|false
+	 * @throws StorageNotAvailableException if the storage is temporarily not available
 	 * @since 9.0.0
 	 */
 	public function free_space($path);
@@ -303,7 +329,8 @@ public function free_space($path);
 	 *
 	 * @param string $path
 	 * @param int $mtime
-	 * @return bool
+	 * @return bool true on success, false otherwise
+	 * @throws StorageNotAvailableException if the storage is temporarily not available
 	 * @since 9.0.0
 	 */
 	public function touch($path, $mtime = null);
@@ -314,6 +341,7 @@ public function touch($path, $mtime = null);
 	 *
 	 * @param string $path
 	 * @return string|false
+	 * @throws StorageNotAvailableException if the storage is temporarily not available
 	 * @since 9.0.0
 	 */
 	public function getLocalFile($path);
@@ -324,6 +352,7 @@ public function getLocalFile($path);
 	 * @param string $path
 	 * @param int $time
 	 * @return bool
+	 * @throws StorageNotAvailableException if the storage is temporarily not available
 	 * @since 9.0.0
 	 *
 	 * hasUpdated for folders should return at least true if a file inside the folder is add, removed or renamed.
@@ -336,6 +365,7 @@ public function hasUpdated($path, $time);
 	 *
 	 * @param string $path
 	 * @return string|false
+	 * @throws StorageNotAvailableException if the storage is temporarily not available
 	 * @since 9.0.0
 	 */
 	public function getETag($path);
@@ -368,6 +398,7 @@ public function instanceOfStorage($class);
 	 *
 	 * @param string $path
 	 * @return array|false
+	 * @throws StorageNotAvailableException if the storage is temporarily not available
 	 * @since 9.0.0
 	 */
 	public function getDirectDownload($path);
@@ -386,6 +417,7 @@ public function verifyPath($path, $fileName);
 	 * @param string $sourceInternalPath
 	 * @param string $targetInternalPath
 	 * @return bool
+	 * @throws StorageNotAvailableException if the storage is temporarily not available
 	 * @since 9.0.0
 	 */
 	public function copyFromStorage(\OCP\Files\Storage $sourceStorage, $sourceInternalPath, $targetInternalPath);
@@ -395,6 +427,7 @@ public function copyFromStorage(\OCP\Files\Storage $sourceStorage, $sourceIntern
 	 * @param string $sourceInternalPath
 	 * @param string $targetInternalPath
 	 * @return bool
+	 * @throws StorageNotAvailableException if the storage is temporarily not available
 	 * @since 9.0.0
 	 */
 	public function moveFromStorage(\OCP\Files\Storage $sourceStorage, $sourceInternalPath, $targetInternalPath);
@@ -408,49 +441,72 @@ public function moveFromStorage(\OCP\Files\Storage $sourceStorage, $sourceIntern
 	public function test();
 
 	/**
+	 * Returns the availability info
+	 *
 	 * @since 9.0.0
 	 * @return array [ available, last_checked ]
 	 */
 	public function getAvailability();
 
 	/**
+	 * Sets availability flag
+	 *
 	 * @since 9.0.0
 	 * @param bool $isAvailable
 	 */
 	public function setAvailability($isAvailable);
 
 	/**
+	 * Returns the owner name
+	 *
 	 * @param string $path path for which to retrieve the owner
+	 * @return string owner name
+	 * @throws StorageNotAvailableException if the storage is temporarily not available
 	 * @since 9.0.0
 	 */
 	public function getOwner($path);
 
 	/**
+	 * Returns the storage cache instance
+	 *
 	 * @return ICache
+	 * @throws StorageNotAvailableException if the storage is temporarily not available
 	 * @since 9.0.0
 	 */
 	public function getCache();
 
 	/**
+	 * Returns the change propagator instance
+	 *
 	 * @return IPropagator
+	 * @throws StorageNotAvailableException if the storage is temporarily not available
 	 * @since 9.0.0
 	 */
 	public function getPropagator();
 
 	/**
+	 * Returns the scanner instance
+	 *
 	 * @return IScanner
+	 * @throws StorageNotAvailableException if the storage is temporarily not available
 	 * @since 9.0.0
 	 */
 	public function getScanner();
 
 	/**
+	 * Returns the updater instance
+	 *
 	 * @return IUpdater
+	 * @throws StorageNotAvailableException if the storage is temporarily not available
 	 * @since 9.0.0
 	 */
 	public function getUpdater();
 
 	/**
+	 * Returns the watched instance
+	 *
 	 * @return IWatcher
+	 * @throws StorageNotAvailableException if the storage is temporarily not available
 	 * @since 9.0.0
 	 */
 	public function getWatcher();
diff --git a/lib/public/Files/Storage/PolyFill/CopyDirectory.php b/lib/public/Files/Storage/PolyFill/CopyDirectory.php
new file mode 100644
index 000000000000..994f48c13a95
--- /dev/null
+++ b/lib/public/Files/Storage/PolyFill/CopyDirectory.php
@@ -0,0 +1,30 @@
+<?php
+/**
+ * @author Vincent Petry <pvince81@owncloud.com>
+ *
+ * @copyright Copyright (c) 2016, ownCloud GmbH.
+ * @license AGPL-3.0
+ *
+ * This code is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License, version 3,
+ * as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License, version 3,
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>
+ *
+ */
+
+namespace OCP\Files\Storage\PolyFill;
+
+/**
+ * @since 9.2
+ */
+trait CopyDirectory {
+	use \OC\Files\Storage\PolyFill\CopyDirectory;
+}
+
diff --git a/lib/public/Files/Storage/StorageAdapter.php b/lib/public/Files/Storage/StorageAdapter.php
new file mode 100644
index 000000000000..37dee8557df8
--- /dev/null
+++ b/lib/public/Files/Storage/StorageAdapter.php
@@ -0,0 +1,137 @@
+<?php
+/**
+ * @author Vincent Petry <pvince81@owncloud.com>
+ *
+ * @copyright Copyright (c) 2016, ownCloud GmbH.
+ * @license AGPL-3.0
+ *
+ * This code is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License, version 3,
+ * as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License, version 3,
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>
+ *
+ */
+
+namespace OCP\Files\Storage;
+
+use OCP\Files\StorageNotAvailableException;
+
+/**
+ * Storage adapter implementing most of the common methods from IStorage.
+ *
+ * @since 9.2
+ */
+abstract class StorageAdapter extends \OC\Files\Storage\Common {
+
+	/**
+	 * Get the identifier for the storage,
+	 * the returned id should be the same for every storage object that is created with the same parameters
+	 * and two storage objects with the same id should refer to two storages that display the same files.
+	 *
+	 * @return string storage id
+	 * @since 9.2
+	 */
+	abstract public function getId();
+
+	/**
+	 * see http://php.net/manual/en/function.mkdir.php
+	 * implementations need to implement a recursive mkdir
+	 *
+	 * @param string $path
+	 * @return bool true on success, false otherwise
+	 * @throws StorageNotAvailableException if the storage is temporarily not available
+	 * @since 9.2
+	 */
+	abstract public function mkdir($path);
+
+	/**
+	 * see http://php.net/manual/en/function.rmdir.php
+	 *
+	 * @param string $path
+	 * @return bool true on success, false otherwise
+	 * @throws StorageNotAvailableException if the storage is temporarily not available
+	 * @since 9.2
+	 */
+	abstract public function rmdir($path);
+
+	/**
+	 * see http://php.net/manual/en/function.opendir.php
+	 *
+	 * @param string $path
+	 * @return resource|false
+	 * @throws StorageNotAvailableException if the storage is temporarily not available
+	 * @since 9.2
+	 */
+	abstract public function opendir($path);
+
+	/**
+	 * see http://php.net/manual/en/function.stat.php
+	 * only the following keys are required in the result: size and mtime
+	 *
+	 * @param string $path
+	 * @return array|false
+	 * @throws StorageNotAvailableException if the storage is temporarily not available
+	 * @since 9.2
+	 */
+	abstract public function stat($path);
+
+	/**
+	 * see http://php.net/manual/en/function.filetype.php
+	 *
+	 * @param string $path
+	 * @return string|false
+	 * @throws StorageNotAvailableException if the storage is temporarily not available
+	 * @since 9.2
+	 */
+	abstract public function filetype($path);
+
+	/**
+	 * see http://php.net/manual/en/function.file_exists.php
+	 *
+	 * @param string $path
+	 * @return bool
+	 * @throws StorageNotAvailableException if the storage is temporarily not available
+	 * @since 9.2
+	 */
+	abstract public function file_exists($path);
+
+	/**
+	 * see http://php.net/manual/en/function.unlink.php
+	 *
+	 * @param string $path
+	 * @return bool true on success, false otherwise
+	 * @throws StorageNotAvailableException if the storage is temporarily not available
+	 * @since 9.2
+	 */
+	abstract public function unlink($path);
+
+	/**
+	 * see http://php.net/manual/en/function.fopen.php
+	 *
+	 * @param string $path
+	 * @param string $mode
+	 * @return resource|false
+	 * @throws StorageNotAvailableException if the storage is temporarily not available
+	 * @since 9.2
+	 */
+	abstract public function fopen($path, $mode);
+
+	/**
+	 * see http://php.net/manual/en/function.touch.php
+	 * If the backend does not support the operation, false should be returned
+	 *
+	 * @param string $path
+	 * @param int $mtime
+	 * @return bool true on success, false otherwise
+	 * @throws StorageNotAvailableException if the storage is temporarily not available
+	 * @since 9.2
+	 */
+	abstract public function touch($path, $mtime = NULL);
+}