diff --git a/radicale/storage/__init__.py b/radicale/storage/__init__.py
index 473eed7..1d703d2 100644
--- a/radicale/storage/__init__.py
+++ b/radicale/storage/__init__.py
@@ -49,17 +49,12 @@ def load(configuration):
     else:
         module = storage_type
     try:
-        class_ = import_module(module).Collection
+        class_ = import_module(module).Storage
     except Exception as e:
         raise RuntimeError("Failed to load storage module %r: %s" %
                            (module, e)) from e
     logger.info("Storage type is %r", storage_type)
-
-    class CollectionCopy(class_):
-        """Collection copy, avoids overriding the original class attributes."""
-    CollectionCopy.configuration = configuration
-    CollectionCopy.static_init()
-    return CollectionCopy
+    return class_(configuration)
 
 
 class ComponentExistsError(ValueError):
@@ -76,17 +71,11 @@ class ComponentNotFoundError(ValueError):
 
 class BaseCollection:
 
-    # Overriden on copy by the "load" function
-    configuration = None
-
-    # Properties of instance
-    """The sanitized path of the collection without leading or trailing ``/``.
-    """
-    path = ""
-
-    @classmethod
-    def static_init(cls):
-        """init collection copy"""
+    @property
+    def path(self):
+        """The sanitized path of the collection without leading or
+        trailing ``/``."""
+        raise NotImplementedError
 
     @property
     def owner(self):
@@ -98,37 +87,6 @@ class BaseCollection:
         """Collection is a principal."""
         return bool(self.path) and "/" not in self.path
 
-    @classmethod
-    def discover(cls, path, depth="0"):
-        """Discover a list of collections under the given ``path``.
-
-        ``path`` is sanitized.
-
-        If ``depth`` is "0", only the actual object under ``path`` is
-        returned.
-
-        If ``depth`` is anything but "0", it is considered as "1" and direct
-        children are included in the result.
-
-        The root collection "/" must always exist.
-
-        """
-        raise NotImplementedError
-
-    @classmethod
-    def move(cls, item, to_collection, to_href):
-        """Move an object.
-
-        ``item`` is the item to move.
-
-        ``to_collection`` is the target collection.
-
-        ``to_href`` is the target name in ``to_collection``. An item with the
-        same name might already exist.
-
-        """
-        raise NotImplementedError
-
     @property
     def etag(self):
         """Encoded as quoted-string (see RFC 2616)."""
@@ -138,27 +96,6 @@ class BaseCollection:
         etag.update(json.dumps(self.get_meta(), sort_keys=True).encode())
         return '"%s"' % etag.hexdigest()
 
-    @classmethod
-    def create_collection(cls, href, items=None, props=None):
-        """Create a collection.
-
-        ``href`` is the sanitized path.
-
-        If the collection already exists and neither ``collection`` nor
-        ``props`` are set, this method shouldn't do anything. Otherwise the
-        existing collection must be replaced.
-
-        ``collection`` is a list of vobject components.
-
-        ``props`` are metadata values for the collection.
-
-        ``props["tag"]`` is the type of collection (VCALENDAR or
-        VADDRESSBOOK). If the key ``tag`` is missing, it is guessed from the
-        collection.
-
-        """
-        raise NotImplementedError
-
     def sync(self, old_token=None):
         """Get the current sync token and changed items for synchronization.
 
@@ -318,9 +255,69 @@ class BaseCollection:
             return "".join((item.serialize() for item in self.get_all()))
         return ""
 
-    @classmethod
+
+class BaseStorage:
+    def __init__(self, configuration):
+        """Initialize BaseStorage.
+
+        ``configuration`` see ``radicale.config`` module.
+        The ``configuration`` must not change during the lifetime of
+        this object, it is kept as an internal reference.
+
+        """
+        self.configuration = configuration
+
+    def discover(self, path, depth="0"):
+        """Discover a list of collections under the given ``path``.
+
+        ``path`` is sanitized.
+
+        If ``depth`` is "0", only the actual object under ``path`` is
+        returned.
+
+        If ``depth`` is anything but "0", it is considered as "1" and direct
+        children are included in the result.
+
+        The root collection "/" must always exist.
+
+        """
+        raise NotImplementedError
+
+    def move(self, item, to_collection, to_href):
+        """Move an object.
+
+        ``item`` is the item to move.
+
+        ``to_collection`` is the target collection.
+
+        ``to_href`` is the target name in ``to_collection``. An item with the
+        same name might already exist.
+
+        """
+        raise NotImplementedError
+
+    def create_collection(self, href, items=None, props=None):
+        """Create a collection.
+
+        ``href`` is the sanitized path.
+
+        If the collection already exists and neither ``collection`` nor
+        ``props`` are set, this method shouldn't do anything. Otherwise the
+        existing collection must be replaced.
+
+        ``collection`` is a list of vobject components.
+
+        ``props`` are metadata values for the collection.
+
+        ``props["tag"]`` is the type of collection (VCALENDAR or
+        VADDRESSBOOK). If the key ``tag`` is missing, it is guessed from the
+        collection.
+
+        """
+        raise NotImplementedError
+
     @contextlib.contextmanager
-    def acquire_lock(cls, mode, user=None):
+    def acquire_lock(self, mode, user=None):
         """Set a context manager to lock the whole storage.
 
         ``mode`` must either be "r" for shared access or "w" for exclusive
@@ -331,7 +328,6 @@ class BaseCollection:
         """
         raise NotImplementedError
 
-    @classmethod
-    def verify(cls):
+    def verify(self):
         """Check the storage for errors."""
         raise NotImplementedError
diff --git a/radicale/storage/multifilesystem/__init__.py b/radicale/storage/multifilesystem/__init__.py
index 38b5e71..b7fdbc3 100644
--- a/radicale/storage/multifilesystem/__init__.py
+++ b/radicale/storage/multifilesystem/__init__.py
@@ -32,49 +32,40 @@ from tempfile import NamedTemporaryFile
 from radicale import pathutils, storage
 from radicale.storage.multifilesystem.cache import CollectionCacheMixin
 from radicale.storage.multifilesystem.create_collection import \
-    CollectionCreateCollectionMixin
+    StorageCreateCollectionMixin
 from radicale.storage.multifilesystem.delete import CollectionDeleteMixin
-from radicale.storage.multifilesystem.discover import CollectionDiscoverMixin
+from radicale.storage.multifilesystem.discover import StorageDiscoverMixin
 from radicale.storage.multifilesystem.get import CollectionGetMixin
 from radicale.storage.multifilesystem.history import CollectionHistoryMixin
-from radicale.storage.multifilesystem.lock import CollectionLockMixin
+from radicale.storage.multifilesystem.lock import (CollectionLockMixin,
+                                                   StorageLockMixin)
 from radicale.storage.multifilesystem.meta import CollectionMetaMixin
-from radicale.storage.multifilesystem.move import CollectionMoveMixin
+from radicale.storage.multifilesystem.move import StorageMoveMixin
 from radicale.storage.multifilesystem.sync import CollectionSyncMixin
 from radicale.storage.multifilesystem.upload import CollectionUploadMixin
-from radicale.storage.multifilesystem.verify import CollectionVerifyMixin
+from radicale.storage.multifilesystem.verify import StorageVerifyMixin
 
 
 class Collection(
-        CollectionCacheMixin, CollectionCreateCollectionMixin,
-        CollectionDeleteMixin, CollectionDiscoverMixin, CollectionGetMixin,
+        CollectionCacheMixin, CollectionDeleteMixin, CollectionGetMixin,
         CollectionHistoryMixin, CollectionLockMixin, CollectionMetaMixin,
-        CollectionMoveMixin, CollectionSyncMixin, CollectionUploadMixin,
-        CollectionVerifyMixin, storage.BaseCollection):
-    """Collection stored in several files per calendar."""
+        CollectionSyncMixin, CollectionUploadMixin, storage.BaseCollection):
 
-    @classmethod
-    def static_init(cls):
-        folder = cls.configuration.get("storage", "filesystem_folder")
-        cls._makedirs_synced(folder)
-        super().static_init()
-
-    def __init__(self, path, filesystem_path=None):
-        folder = self._get_collection_root_folder()
+    def __init__(self, storage, path, filesystem_path=None):
+        self._storage = storage
+        folder = storage._get_collection_root_folder()
         # Path should already be sanitized
-        self.path = pathutils.strip_path(path)
-        self._encoding = self.configuration.get("encoding", "stock")
+        self._path = pathutils.strip_path(path)
+        self._encoding = self._storage.configuration.get("encoding", "stock")
         if filesystem_path is None:
             filesystem_path = pathutils.path_to_filesystem(folder, self.path)
         self._filesystem_path = filesystem_path
         self._etag_cache = None
         super().__init__()
 
-    @classmethod
-    def _get_collection_root_folder(cls):
-        filesystem_folder = cls.configuration.get(
-            "storage", "filesystem_folder")
-        return os.path.join(filesystem_folder, "collection-root")
+    @property
+    def path(self):
+        return self._path
 
     @contextlib.contextmanager
     def _atomic_write(self, path, mode="w", newline=None, sync_directory=True,
@@ -87,7 +78,7 @@ class Collection(
             yield tmp
             tmp.flush()
             try:
-                self._fsync(tmp.fileno())
+                self._storage._fsync(tmp.fileno())
             except OSError as e:
                 raise RuntimeError("Fsync'ing file %r failed: %s" %
                                    (path, e)) from e
@@ -98,50 +89,7 @@ class Collection(
             os.remove(tmp.name)
             raise
         if sync_directory:
-            self._sync_directory(directory)
-
-    @classmethod
-    def _fsync(cls, fd):
-        if cls.configuration.get("internal", "filesystem_fsync"):
-            pathutils.fsync(fd)
-
-    @classmethod
-    def _sync_directory(cls, path):
-        """Sync directory to disk.
-
-        This only works on POSIX and does nothing on other systems.
-
-        """
-        if not cls.configuration.get("internal", "filesystem_fsync"):
-            return
-        if os.name == "posix":
-            try:
-                fd = os.open(path, 0)
-                try:
-                    cls._fsync(fd)
-                finally:
-                    os.close(fd)
-            except OSError as e:
-                raise RuntimeError("Fsync'ing directory %r failed: %s" %
-                                   (path, e)) from e
-
-    @classmethod
-    def _makedirs_synced(cls, filesystem_path):
-        """Recursively create a directory and its parents in a sync'ed way.
-
-        This method acts silently when the folder already exists.
-
-        """
-        if os.path.isdir(filesystem_path):
-            return
-        parent_filesystem_path = os.path.dirname(filesystem_path)
-        # Prevent infinite loop
-        if filesystem_path != parent_filesystem_path:
-            # Create parent dirs recursively
-            cls._makedirs_synced(parent_filesystem_path)
-        # Possible race!
-        os.makedirs(filesystem_path, exist_ok=True)
-        cls._sync_directory(parent_filesystem_path)
+            self._storage._sync_directory(directory)
 
     @property
     def last_modified(self):
@@ -155,6 +103,63 @@ class Collection(
     @property
     def etag(self):
         # reuse cached value if the storage is read-only
-        if self._lock.locked == "w" or self._etag_cache is None:
+        if self._storage._lock.locked == "w" or self._etag_cache is None:
             self._etag_cache = super().etag
         return self._etag_cache
+
+
+class Storage(
+        StorageCreateCollectionMixin, StorageDiscoverMixin, StorageLockMixin,
+        StorageMoveMixin, StorageVerifyMixin, storage.BaseStorage):
+
+    _collection_class = Collection
+
+    def __init__(self, configuration):
+        folder = configuration.get("storage", "filesystem_folder")
+        self._makedirs_synced(folder)
+        super().__init__(configuration)
+
+    def _get_collection_root_folder(self):
+        filesystem_folder = self.configuration.get(
+            "storage", "filesystem_folder")
+        return os.path.join(filesystem_folder, "collection-root")
+
+    def _fsync(self, fd):
+        if self.configuration.get("internal", "filesystem_fsync"):
+            pathutils.fsync(fd)
+
+    def _sync_directory(self, path):
+        """Sync directory to disk.
+
+        This only works on POSIX and does nothing on other systems.
+
+        """
+        if not self.configuration.get("internal", "filesystem_fsync"):
+            return
+        if os.name == "posix":
+            try:
+                fd = os.open(path, 0)
+                try:
+                    self._fsync(fd)
+                finally:
+                    os.close(fd)
+            except OSError as e:
+                raise RuntimeError("Fsync'ing directory %r failed: %s" %
+                                   (path, e)) from e
+
+    def _makedirs_synced(self, filesystem_path):
+        """Recursively create a directory and its parents in a sync'ed way.
+
+        This method acts silently when the folder already exists.
+
+        """
+        if os.path.isdir(filesystem_path):
+            return
+        parent_filesystem_path = os.path.dirname(filesystem_path)
+        # Prevent infinite loop
+        if filesystem_path != parent_filesystem_path:
+            # Create parent dirs recursively
+            self._makedirs_synced(parent_filesystem_path)
+        # Possible race!
+        os.makedirs(filesystem_path, exist_ok=True)
+        self._sync_directory(parent_filesystem_path)
diff --git a/radicale/storage/multifilesystem/cache.py b/radicale/storage/multifilesystem/cache.py
index 97296bc..56812ed 100644
--- a/radicale/storage/multifilesystem/cache.py
+++ b/radicale/storage/multifilesystem/cache.py
@@ -26,8 +26,7 @@ from radicale.log import logger
 
 
 class CollectionCacheMixin:
-    @classmethod
-    def _clean_cache(cls, folder, names, max_age=None):
+    def _clean_cache(self, folder, names, max_age=None):
         """Delete all ``names`` in ``folder`` that are older than ``max_age``.
         """
         age_limit = time.time() - max_age if max_age is not None else None
@@ -52,7 +51,7 @@ class CollectionCacheMixin:
                 continue
             modified = True
         if modified:
-            cls._sync_directory(folder)
+            self._storage._sync_directory(folder)
 
     def _item_cache_hash(self, raw_text):
         _hash = md5()
@@ -71,7 +70,7 @@ class CollectionCacheMixin:
         cache_folder = os.path.join(self._filesystem_path, ".Radicale.cache",
                                     "item")
         content = self._item_cache_content(item, cache_hash)
-        self._makedirs_synced(cache_folder)
+        self._storage._makedirs_synced(cache_folder)
         try:
             # Race: Other processes might have created and locked the
             # file.
diff --git a/radicale/storage/multifilesystem/create_collection.py b/radicale/storage/multifilesystem/create_collection.py
index be7fc9c..1ebaa24 100644
--- a/radicale/storage/multifilesystem/create_collection.py
+++ b/radicale/storage/multifilesystem/create_collection.py
@@ -22,21 +22,25 @@ from tempfile import TemporaryDirectory
 from radicale import pathutils
 
 
-class CollectionCreateCollectionMixin:
-    @classmethod
-    def create_collection(cls, href, items=None, props=None):
-        folder = cls._get_collection_root_folder()
+class StorageCreateCollectionMixin:
+
+    def __init__(self, configuration):
+        super().__init__(configuration)
+
+    def create_collection(self, href, items=None, props=None):
+        folder = self._get_collection_root_folder()
 
         # Path should already be sanitized
         sane_path = pathutils.strip_path(href)
         filesystem_path = pathutils.path_to_filesystem(folder, sane_path)
 
         if not props:
-            cls._makedirs_synced(filesystem_path)
-            return cls(pathutils.unstrip_path(sane_path, True))
+            self._makedirs_synced(filesystem_path)
+            return self._collection_class(
+                self, pathutils.unstrip_path(sane_path, True))
 
         parent_dir = os.path.dirname(filesystem_path)
-        cls._makedirs_synced(parent_dir)
+        self._makedirs_synced(parent_dir)
 
         # Create a temporary directory with an unsafe name
         with TemporaryDirectory(
@@ -44,14 +48,15 @@ class CollectionCreateCollectionMixin:
             # The temporary directory itself can't be renamed
             tmp_filesystem_path = os.path.join(tmp_dir, "collection")
             os.makedirs(tmp_filesystem_path)
-            self = cls(pathutils.unstrip_path(sane_path, True),
-                       filesystem_path=tmp_filesystem_path)
-            self.set_meta(props)
+            col = self._collection_class(
+                self, pathutils.unstrip_path(sane_path, True),
+                filesystem_path=tmp_filesystem_path)
+            col.set_meta(props)
             if items is not None:
                 if props.get("tag") == "VCALENDAR":
-                    self._upload_all_nonatomic(items, suffix=".ics")
+                    col._upload_all_nonatomic(items, suffix=".ics")
                 elif props.get("tag") == "VADDRESSBOOK":
-                    self._upload_all_nonatomic(items, suffix=".vcf")
+                    col._upload_all_nonatomic(items, suffix=".vcf")
 
             # This operation is not atomic on the filesystem level but it's
             # very unlikely that one rename operations succeeds while the
@@ -59,6 +64,7 @@ class CollectionCreateCollectionMixin:
             if os.path.exists(filesystem_path):
                 os.rename(filesystem_path, os.path.join(tmp_dir, "delete"))
             os.rename(tmp_filesystem_path, filesystem_path)
-            cls._sync_directory(parent_dir)
+            self._sync_directory(parent_dir)
 
-        return cls(pathutils.unstrip_path(sane_path, True))
+        return self._collection_class(
+            self, pathutils.unstrip_path(sane_path, True))
diff --git a/radicale/storage/multifilesystem/delete.py b/radicale/storage/multifilesystem/delete.py
index c29b9bf..264b608 100644
--- a/radicale/storage/multifilesystem/delete.py
+++ b/radicale/storage/multifilesystem/delete.py
@@ -34,9 +34,9 @@ class CollectionDeleteMixin:
                         prefix=".Radicale.tmp-", dir=parent_dir) as tmp:
                     os.rename(self._filesystem_path, os.path.join(
                         tmp, os.path.basename(self._filesystem_path)))
-                    self._sync_directory(parent_dir)
+                    self._storage._sync_directory(parent_dir)
             else:
-                self._sync_directory(parent_dir)
+                self._storage._sync_directory(parent_dir)
         else:
             # Delete an item
             if not pathutils.is_safe_filesystem_path_component(href):
@@ -45,7 +45,7 @@ class CollectionDeleteMixin:
             if not os.path.isfile(path):
                 raise storage.ComponentNotFoundError(href)
             os.remove(path)
-            self._sync_directory(os.path.dirname(path))
+            self._storage._sync_directory(os.path.dirname(path))
             # Track the change
             self._update_history_etag(href, None)
             self._clean_history()
diff --git a/radicale/storage/multifilesystem/discover.py b/radicale/storage/multifilesystem/discover.py
index c4409cf..4c9aaa8 100644
--- a/radicale/storage/multifilesystem/discover.py
+++ b/radicale/storage/multifilesystem/discover.py
@@ -24,17 +24,20 @@ from radicale import pathutils
 from radicale.log import logger
 
 
-class CollectionDiscoverMixin:
-    @classmethod
-    def discover(cls, path, depth="0", child_context_manager=(
+class StorageDiscoverMixin:
+
+    def __init__(self, configuration):
+        super().__init__(configuration)
+
+    def discover(self, path, depth="0", child_context_manager=(
                  lambda path, href=None: contextlib.ExitStack())):
         # Path should already be sanitized
         sane_path = pathutils.strip_path(path)
         attributes = sane_path.split("/") if sane_path else []
 
-        folder = cls._get_collection_root_folder()
+        folder = self._get_collection_root_folder()
         # Create the root collection
-        cls._makedirs_synced(folder)
+        self._makedirs_synced(folder)
         try:
             filesystem_path = pathutils.path_to_filesystem(folder, sane_path)
         except ValueError as e:
@@ -53,7 +56,8 @@ class CollectionDiscoverMixin:
             href = None
 
         sane_path = "/".join(attributes)
-        collection = cls(pathutils.unstrip_path(sane_path, True))
+        collection = self._collection_class(
+            self, pathutils.unstrip_path(sane_path, True))
 
         if href:
             yield collection._get(href)
@@ -80,4 +84,4 @@ class CollectionDiscoverMixin:
             sane_child_path = posixpath.join(sane_path, href)
             child_path = pathutils.unstrip_path(sane_child_path, True)
             with child_context_manager(sane_child_path):
-                yield cls(child_path)
+                yield self._collection_class(self, child_path)
diff --git a/radicale/storage/multifilesystem/get.py b/radicale/storage/multifilesystem/get.py
index 41af0a2..0721450 100644
--- a/radicale/storage/multifilesystem/get.py
+++ b/radicale/storage/multifilesystem/get.py
@@ -77,7 +77,7 @@ class CollectionGetMixin:
                 # Lock the item cache to prevent multpile processes from
                 # generating the same data in parallel.
                 # This improves the performance for multiple requests.
-                if self._lock.locked == "r":
+                if self._storage._lock.locked == "r":
                     # Check if another process created the file in the meantime
                     cache_hash, uid, etag, text, name, tag, start, end = \
                         self._load_item_cache(href, input_hash)
diff --git a/radicale/storage/multifilesystem/history.py b/radicale/storage/multifilesystem/history.py
index 31159f6..36d4219 100644
--- a/radicale/storage/multifilesystem/history.py
+++ b/radicale/storage/multifilesystem/history.py
@@ -50,7 +50,7 @@ class CollectionHistoryMixin:
             history_etag = binascii.hexlify(os.urandom(16)).decode("ascii")
         etag = item.etag if item else ""
         if etag != cache_etag:
-            self._makedirs_synced(history_folder)
+            self._storage._makedirs_synced(history_folder)
             history_etag = radicale_item.get_etag(
                 history_etag + "/" + etag).strip("\"")
             try:
@@ -83,5 +83,5 @@ class CollectionHistoryMixin:
         history_folder = os.path.join(self._filesystem_path,
                                       ".Radicale.cache", "history")
         self._clean_cache(history_folder, self._get_deleted_history_hrefs(),
-                          max_age=self.configuration.get(
+                          max_age=self._storage.configuration.get(
                               "storage", "max_sync_token_age"))
diff --git a/radicale/storage/multifilesystem/lock.py b/radicale/storage/multifilesystem/lock.py
index 01456c0..df3c76a 100644
--- a/radicale/storage/multifilesystem/lock.py
+++ b/radicale/storage/multifilesystem/lock.py
@@ -27,32 +27,32 @@ from radicale.log import logger
 
 
 class CollectionLockMixin:
-    @classmethod
-    def static_init(cls):
-        super().static_init()
-        folder = cls.configuration.get("storage", "filesystem_folder")
-        lock_path = os.path.join(folder, ".Radicale.lock")
-        cls._lock = pathutils.RwLock(lock_path)
-
     def _acquire_cache_lock(self, ns=""):
-        if self._lock.locked == "w":
+        if self._storage._lock.locked == "w":
             return contextlib.ExitStack()
         cache_folder = os.path.join(self._filesystem_path, ".Radicale.cache")
-        self._makedirs_synced(cache_folder)
+        self._storage._makedirs_synced(cache_folder)
         lock_path = os.path.join(cache_folder,
                                  ".Radicale.lock" + (".%s" % ns if ns else ""))
         lock = pathutils.RwLock(lock_path)
         return lock.acquire("w")
 
-    @classmethod
+
+class StorageLockMixin:
+    def __init__(self, configuration):
+        super().__init__(configuration)
+        folder = self.configuration.get("storage", "filesystem_folder")
+        lock_path = os.path.join(folder, ".Radicale.lock")
+        self._lock = pathutils.RwLock(lock_path)
+
     @contextlib.contextmanager
-    def acquire_lock(cls, mode, user=None):
-        with cls._lock.acquire(mode):
+    def acquire_lock(self, mode, user=None):
+        with self._lock.acquire(mode):
             yield
             # execute hook
-            hook = cls.configuration.get("storage", "hook")
+            hook = self.configuration.get("storage", "hook")
             if mode == "w" and hook:
-                folder = cls.configuration.get("storage", "filesystem_folder")
+                folder = self.configuration.get("storage", "filesystem_folder")
                 logger.debug("Running hook")
                 debug = logger.isEnabledFor(logging.DEBUG)
                 p = subprocess.Popen(
diff --git a/radicale/storage/multifilesystem/meta.py b/radicale/storage/multifilesystem/meta.py
index b4594a2..c0dfa9b 100644
--- a/radicale/storage/multifilesystem/meta.py
+++ b/radicale/storage/multifilesystem/meta.py
@@ -31,7 +31,7 @@ class CollectionMetaMixin:
 
     def get_meta(self, key=None):
         # reuse cached value if the storage is read-only
-        if self._lock.locked == "w" or self._meta_cache is None:
+        if self._storage._lock.locked == "w" or self._meta_cache is None:
             try:
                 try:
                     with open(self._props_path, encoding=self._encoding) as f:
diff --git a/radicale/storage/multifilesystem/move.py b/radicale/storage/multifilesystem/move.py
index 99b93d9..4de6518 100644
--- a/radicale/storage/multifilesystem/move.py
+++ b/radicale/storage/multifilesystem/move.py
@@ -21,9 +21,11 @@ import os
 from radicale import pathutils
 
 
-class CollectionMoveMixin:
-    @classmethod
-    def move(cls, item, to_collection, to_href):
+class StorageMoveMixin:
+    def __init__(self, configuration):
+        super().__init__(configuration)
+
+    def move(self, item, to_collection, to_href):
         if not pathutils.is_safe_filesystem_path_component(to_href):
             raise pathutils.UnsafePathError(to_href)
         os.replace(
@@ -31,24 +33,24 @@ class CollectionMoveMixin:
                 item.collection._filesystem_path, item.href),
             pathutils.path_to_filesystem(
                 to_collection._filesystem_path, to_href))
-        cls._sync_directory(to_collection._filesystem_path)
+        self._sync_directory(to_collection._filesystem_path)
         if item.collection._filesystem_path != to_collection._filesystem_path:
-            cls._sync_directory(item.collection._filesystem_path)
+            self._sync_directory(item.collection._filesystem_path)
         # Move the item cache entry
         cache_folder = os.path.join(item.collection._filesystem_path,
                                     ".Radicale.cache", "item")
         to_cache_folder = os.path.join(to_collection._filesystem_path,
                                        ".Radicale.cache", "item")
-        cls._makedirs_synced(to_cache_folder)
+        self._makedirs_synced(to_cache_folder)
         try:
             os.replace(os.path.join(cache_folder, item.href),
                        os.path.join(to_cache_folder, to_href))
         except FileNotFoundError:
             pass
         else:
-            cls._makedirs_synced(to_cache_folder)
+            self._makedirs_synced(to_cache_folder)
             if cache_folder != to_cache_folder:
-                cls._makedirs_synced(cache_folder)
+                self._makedirs_synced(cache_folder)
         # Track the change
         to_collection._update_history_etag(to_href, item)
         item.collection._update_history_etag(item.href, None)
diff --git a/radicale/storage/multifilesystem/sync.py b/radicale/storage/multifilesystem/sync.py
index e20e398..68e0384 100644
--- a/radicale/storage/multifilesystem/sync.py
+++ b/radicale/storage/multifilesystem/sync.py
@@ -86,7 +86,7 @@ class CollectionSyncMixin:
         # write the new token state or update the modification time of
         # existing token state
         if not os.path.exists(token_path):
-            self._makedirs_synced(token_folder)
+            self._storage._makedirs_synced(token_folder)
             try:
                 # Race: Other processes might have created and locked the file.
                 with self._atomic_write(token_path, "wb") as f:
@@ -96,7 +96,7 @@ class CollectionSyncMixin:
             else:
                 # clean up old sync tokens and item cache
                 self._clean_cache(token_folder, os.listdir(token_folder),
-                                  max_age=self.configuration.get(
+                                  max_age=self._storage.configuration.get(
                                       "storage", "max_sync_token_age"))
                 self._clean_history()
         else:
diff --git a/radicale/storage/multifilesystem/upload.py b/radicale/storage/multifilesystem/upload.py
index 53dc869..502b8e4 100644
--- a/radicale/storage/multifilesystem/upload.py
+++ b/radicale/storage/multifilesystem/upload.py
@@ -52,7 +52,7 @@ class CollectionUploadMixin:
         """
         cache_folder = os.path.join(self._filesystem_path,
                                     ".Radicale.cache", "item")
-        self._makedirs_synced(cache_folder)
+        self._storage._makedirs_synced(cache_folder)
         hrefs = set()
         for item in items:
             uid = item.uid
@@ -101,5 +101,5 @@ class CollectionUploadMixin:
             with self._atomic_write(os.path.join(cache_folder, href), "wb",
                                     sync_directory=False) as f:
                 pickle.dump(cache_content, f)
-        self._sync_directory(cache_folder)
-        self._sync_directory(self._filesystem_path)
+        self._storage._sync_directory(cache_folder)
+        self._storage._sync_directory(self._filesystem_path)
diff --git a/radicale/storage/multifilesystem/verify.py b/radicale/storage/multifilesystem/verify.py
index c26f271..61b81d7 100644
--- a/radicale/storage/multifilesystem/verify.py
+++ b/radicale/storage/multifilesystem/verify.py
@@ -22,9 +22,8 @@ from radicale import pathutils, storage
 from radicale.log import logger
 
 
-class CollectionVerifyMixin:
-    @classmethod
-    def verify(cls):
+class StorageVerifyMixin:
+    def verify(self):
         item_errors = collection_errors = 0
 
         @contextlib.contextmanager
@@ -51,7 +50,7 @@ class CollectionVerifyMixin:
                 collection = None
                 uids = set()
                 has_child_collections = False
-                for item in cls.discover(path, "1", exception_cm):
+                for item in self.discover(path, "1", exception_cm):
                     if not collection:
                         collection = item
                         collection.get_meta()
diff --git a/radicale/tests/custom/storage.py b/radicale/tests/custom/storage.py
index c12d7fd..bfcc6e4 100644
--- a/radicale/tests/custom/storage.py
+++ b/radicale/tests/custom/storage.py
@@ -25,8 +25,5 @@ Copy of filesystem storage backend for testing
 from radicale.storage import multifilesystem
 
 
-# TODO: make something more in this collection (and test it)
-class Collection(multifilesystem.Collection):
-    """Collection stored in a folder."""
-    def __init__(self, *args, **kwargs):
-        super().__init__(*args, **kwargs)
+class Storage(multifilesystem.Storage):
+    pass