diff --git a/arangod/Replication/ContinuousSyncer.cpp b/arangod/Replication/ContinuousSyncer.cpp
index 9851852b41..b86ee47580 100644
--- a/arangod/Replication/ContinuousSyncer.cpp
+++ b/arangod/Replication/ContinuousSyncer.cpp
@@ -755,7 +755,7 @@ int ContinuousSyncer::renameCollection(VPackSlice const& slice) {
     return TRI_ERROR_ARANGO_COLLECTION_NOT_FOUND;
   }
 
-  return TRI_RenameCollectionVocBase(_vocbase, col, name.c_str(), true, true);
+  return TRI_RenameCollectionVocBase(_vocbase, col, name, true, true);
 }
 
 ////////////////////////////////////////////////////////////////////////////////
diff --git a/arangod/RestServer/DatabaseFeature.cpp b/arangod/RestServer/DatabaseFeature.cpp
index f00bc9a0a5..8e725d2c9a 100644
--- a/arangod/RestServer/DatabaseFeature.cpp
+++ b/arangod/RestServer/DatabaseFeature.cpp
@@ -143,7 +143,7 @@ void DatabaseManagerThread::run() {
 #endif
   
         LOG(TRACE) << "physically removing database directory '"
-                    << engine->path(database->_id) << "' of database '" << database->name()
+                    << engine->databasePath(database) << "' of database '" << database->name()
                     << "'";
 
         std::string path;
@@ -165,7 +165,7 @@ void DatabaseManagerThread::run() {
         }
 
         // remember db path
-        path = engine->path(database->_id);
+        path = engine->databasePath(database);
 
         TRI_DestroyVocBase(database);
 
@@ -450,6 +450,8 @@ int DatabaseFeature::createDatabaseCoordinator(TRI_voc_tick_t id, std::string co
 
   // name not yet in use, release the read lock
   auto vocbase = std::make_unique<TRI_vocbase_t>(TRI_VOCBASE_TYPE_COORDINATOR, id, name);
+  // vocbase is now active
+  vocbase->_state = (sig_atomic_t)TRI_VOCBASE_STATE_NORMAL;
 
   try {
     vocbase->_replicationApplier.reset(TRI_CreateReplicationApplier(vocbase.get()));
@@ -528,6 +530,8 @@ int DatabaseFeature::createDatabase(TRI_voc_tick_t id, std::string const& name,
     // createDatabase must return a valid database or throw
     vocbase.reset(engine->createDatabase(id, builder.slice())); 
     TRI_ASSERT(vocbase != nullptr);
+    // vocbase is now active
+    vocbase->_state = (sig_atomic_t)TRI_VOCBASE_STATE_NORMAL;
 
     try {
       vocbase->_replicationApplier.reset(TRI_CreateReplicationApplier(vocbase.get()));
@@ -1098,6 +1102,8 @@ int DatabaseFeature::iterateDatabases(VPackSlice const& databases) {
     TRI_vocbase_t* vocbase = engine->openDatabase(it, _upgrade);
     // we found a valid database
     TRI_ASSERT(vocbase != nullptr);
+    // vocbase is now active
+    vocbase->_state = (sig_atomic_t)TRI_VOCBASE_STATE_NORMAL;
     
     try {
       vocbase->_replicationApplier.reset(TRI_CreateReplicationApplier(vocbase));
diff --git a/arangod/StorageEngine/MMFilesEngine.cpp b/arangod/StorageEngine/MMFilesEngine.cpp
index d28464e43f..a22d726221 100644
--- a/arangod/StorageEngine/MMFilesEngine.cpp
+++ b/arangod/StorageEngine/MMFilesEngine.cpp
@@ -25,6 +25,7 @@
 #include "Basics/FileUtils.h"
 #include "Basics/StringUtils.h"
 #include "Basics/VelocyPackHelper.h"
+#include "Basics/WriteLocker.h"
 #include "Basics/files.h"
 #include "RestServer/DatabaseFeature.h"
 #include "RestServer/DatabasePathFeature.h"
@@ -40,6 +41,9 @@
 #include "Indexes/RocksDBIndex.h"
 #endif
 
+#include <velocypack/Iterator.h>
+#include <velocypack/velocypack-aliases.h>
+
 using namespace arangodb;
 using namespace arangodb::basics;
 
@@ -342,20 +346,20 @@ int MMFilesEngine::getCollectionsAndIndexes(TRI_vocbase_t* vocbase,
       continue;
     }
 
-    std::string const file = FileUtils::buildFilename(path, name);
+    std::string const directory = FileUtils::buildFilename(path, name);
 
-    if (!TRI_IsDirectory(file.c_str())) {
-      LOG(DEBUG) << "ignoring non-directory '" << file << "'";
+    if (!TRI_IsDirectory(directory.c_str())) {
+      LOG(DEBUG) << "ignoring non-directory '" << directory << "'";
       continue;
     }
 
-    if (!TRI_IsWritable(file.c_str())) {
+    if (!TRI_IsWritable(directory.c_str())) {
       // the collection directory we found is not writable for the current
       // user
       // this can cause serious trouble so we will abort the server start if
       // we
       // encounter this situation
-      LOG(ERR) << "database subdirectory '" << file
+      LOG(ERR) << "database subdirectory '" << directory
                 << "' is not writable for current user";
 
       return TRI_ERROR_ARANGO_DATADIR_NOT_WRITABLE;
@@ -365,12 +369,12 @@ int MMFilesEngine::getCollectionsAndIndexes(TRI_vocbase_t* vocbase,
 
     try {
       arangodb::VocbaseCollectionInfo info =
-          arangodb::VocbaseCollectionInfo::fromFile(file.c_str(), vocbase,
+          arangodb::VocbaseCollectionInfo::fromFile(directory, vocbase,
                                                     "",  // Name is unused
                                                     true);
      
       if (info.deleted()) {
-        _deleted.emplace_back(std::make_pair(info.name(), file));
+        _deleted.emplace_back(std::make_pair(info.name(), directory));
         continue;
       }
 
@@ -383,44 +387,14 @@ int MMFilesEngine::getCollectionsAndIndexes(TRI_vocbase_t* vocbase,
         return TRI_ERROR_FAILED;
       }
 
+      // add collection info
       result.openObject();
       TRI_CreateVelocyPackCollectionInfo(info, result);
+      result.add("path", VPackValue(directory));
       result.close();
-/*
 
-      } else {
-        // we found a collection that is still active
-        TRI_col_type_e type = info.type();
-        TRI_vocbase_col_t* c = nullptr;
-
-        try {
-          c = AddCollection(vocbase, type, info.name(), info.id(), file);
-        } catch (...) {
-          // if we caught an exception, c is still a nullptr
-        }
-
-        if (c == nullptr) {
-          LOG(ERR) << "failed to add document collection from '"
-                    << file << "'";
-
-          return TRI_set_errno(TRI_ERROR_ARANGO_CORRUPTED_COLLECTION);
-        }
-
-        c->_planId = info.planId();
-        c->_status = TRI_VOC_COL_STATUS_UNLOADED;
-
-        if (!wasCleanShutdown) {
-          // iterating markers may be time-consuming. we'll only do it if
-          // we have to
-          TRI_IterateTicksCollection(file.c_str(), StartupTickIterator, &_maxTick);
-        }
-
-        LOG(DEBUG) << "added document collection '" << info.name()
-                    << "' from '" << file << "'";
-      }
-      */
     } catch (arangodb::basics::Exception const& e) {
-      std::string tmpfile = FileUtils::buildFilename(file, ".tmp");
+      std::string tmpfile = FileUtils::buildFilename(directory, ".tmp");
 
       if (TRI_ExistsFile(tmpfile.c_str())) {
         LOG(TRACE) << "ignoring temporary directory '" << tmpfile << "'";
@@ -432,7 +406,7 @@ int MMFilesEngine::getCollectionsAndIndexes(TRI_vocbase_t* vocbase,
       res = e.code();
 
       LOG(ERR) << "cannot read collection info file in directory '"
-                << file << "': " << TRI_errno_string(res);
+                << directory << "': " << TRI_errno_string(res);
 
       return res;
     }
@@ -761,10 +735,6 @@ std::string MMFilesEngine::databaseDirectory(TRI_voc_tick_t id) const {
   return _databasePath + "database-" + std::to_string(id);
 }
 
-std::string MMFilesEngine::collectionDirectory(TRI_voc_tick_t id, TRI_voc_cid_t cid) const {
-  return basics::FileUtils::buildFilename(databaseDirectory(id), "collection-" + std::to_string(cid));
-}
-
 std::string MMFilesEngine::parametersFile(TRI_voc_tick_t id) const {
   return basics::FileUtils::buildFilename(databaseDirectory(id), TRI_VOC_PARAMETER_FILE);
 }
@@ -800,7 +770,8 @@ int MMFilesEngine::waitForDeletion(std::string const& directoryName, int statusC
 }
 
 /// @brief open an existing database. internal function
-TRI_vocbase_t* MMFilesEngine::openExistingDatabase(TRI_voc_tick_t id, std::string const& name, bool wasCleanShutdown, bool isUpgrade) {
+TRI_vocbase_t* MMFilesEngine::openExistingDatabase(TRI_voc_tick_t id, std::string const& name, 
+                                                   bool wasCleanShutdown, bool isUpgrade) {
   auto vocbase = std::make_unique<TRI_vocbase_t>(TRI_VOCBASE_TYPE_NORMAL, id, name);
 
   // scan the database path for collections
@@ -814,9 +785,32 @@ TRI_vocbase_t* MMFilesEngine::openExistingDatabase(TRI_voc_tick_t id, std::strin
   VPackSlice slice = builder.slice();
   TRI_ASSERT(slice.isArray());
 
-  // vocbase is now active
-  vocbase->_state = (sig_atomic_t)TRI_VOCBASE_STATE_NORMAL;
-  
+  for (auto const& it : VPackArrayIterator(slice)) {
+    arangodb::VocbaseCollectionInfo info(vocbase.get(), it.get("name").copyString(), it, true);
+    
+    // we found a collection that is still active
+    TRI_vocbase_col_t* c = nullptr;
+
+    try {
+      c = TRI_AddCollectionVocBase(ConditionalWriteLocker::DoLock(), vocbase.get(), info.type(), info.id(), info.name(), info.planId(), it.get("path").copyString());
+    } catch (...) {
+      // if we caught an exception, c is still a nullptr
+    }
+
+    if (c == nullptr) {
+      LOG(ERR) << "failed to add document collection '" << info.name() << "'";
+      THROW_ARANGO_EXCEPTION(TRI_ERROR_ARANGO_CORRUPTED_COLLECTION);
+    }
+
+    if (!wasCleanShutdown) {
+      // iterating markers may be time-consuming. we'll only do it if
+      // we have to
+      // TRI_IterateTicksCollection(file.c_str(), StartupTickIterator, &_maxTick);
+    }
+
+    LOG(DEBUG) << "added document collection '" << info.name() << "'";
+  }
+
   // start cleanup thread
   TRI_ASSERT(vocbase->_cleanupThread == nullptr);
   vocbase->_cleanupThread.reset(new CleanupThread(vocbase.get()));
diff --git a/arangod/StorageEngine/MMFilesEngine.h b/arangod/StorageEngine/MMFilesEngine.h
index a1bb94d950..bd2b49c41a 100644
--- a/arangod/StorageEngine/MMFilesEngine.h
+++ b/arangod/StorageEngine/MMFilesEngine.h
@@ -79,10 +79,7 @@ class MMFilesEngine final : public StorageEngine {
   uint64_t getMaxRevision() override;
   
   // return the path for a database
-  std::string path(TRI_voc_tick_t id) const override { return databaseDirectory(id); }
-  
-  // return the path for a collection in the database
-  std::string path(TRI_voc_tick_t id, TRI_voc_cid_t cid) const override { return collectionDirectory(id, cid); };
+  std::string databasePath(TRI_vocbase_t* vocbase) const override { return databaseDirectory(vocbase->_id); }
   
   TRI_vocbase_t* openDatabase(arangodb::velocypack::Slice const& parameters, bool isUpgrade) override;
 
@@ -211,7 +208,6 @@ class MMFilesEngine final : public StorageEngine {
                                                      bool deleted) const;
 
   std::string databaseDirectory(TRI_voc_tick_t id) const;
-  std::string collectionDirectory(TRI_voc_tick_t id, TRI_voc_cid_t cid) const;
   std::string parametersFile(TRI_voc_tick_t id) const;
   int openDatabases();
 
diff --git a/arangod/StorageEngine/OtherEngine.h b/arangod/StorageEngine/OtherEngine.h
index 66fd63b86a..c94a53fec6 100644
--- a/arangod/StorageEngine/OtherEngine.h
+++ b/arangod/StorageEngine/OtherEngine.h
@@ -68,10 +68,7 @@ class OtherEngine final : public StorageEngine {
   uint64_t getMaxRevision() override;
   
   // return the path for a database
-  std::string path(TRI_voc_tick_t id) const override { return "none"; }
-  
-  // return the path for a collection in the database
-  std::string path(TRI_voc_tick_t id, TRI_voc_cid_t cid) const override { return "none"; }
+  std::string databasePath(TRI_vocbase_t*) const override { return "none"; }
   
   TRI_vocbase_t* openDatabase(arangodb::velocypack::Slice const& parameters, bool isUpgrade) override { 
     return nullptr; 
diff --git a/arangod/StorageEngine/StorageEngine.h b/arangod/StorageEngine/StorageEngine.h
index 6fd7340f9a..e961df3982 100644
--- a/arangod/StorageEngine/StorageEngine.h
+++ b/arangod/StorageEngine/StorageEngine.h
@@ -27,12 +27,11 @@
 #include "Basics/Common.h"
 #include "ApplicationFeatures/ApplicationFeature.h"
 #include "VocBase/voc-types.h"
+#include "VocBase/vocbase.h"
 
 #include <velocypack/Builder.h>
 #include <velocypack/Slice.h>
 
-struct TRI_vocbase_t;
-
 namespace arangodb {
 
 class StorageEngine : public application_features::ApplicationFeature {
@@ -86,10 +85,7 @@ class StorageEngine : public application_features::ApplicationFeature {
   virtual uint64_t getMaxRevision() = 0;
 
   // return the path for a database
-  virtual std::string path(TRI_voc_tick_t id) const = 0;
-
-  // return the path for a collection in the database
-  virtual std::string path(TRI_voc_tick_t id, TRI_voc_cid_t cid) const = 0;
+  virtual std::string databasePath(TRI_vocbase_t* vocbase) const = 0;
 
   virtual TRI_vocbase_t* openDatabase(arangodb::velocypack::Slice const& parameters, bool isUpgrade) = 0;
 
diff --git a/arangod/Utils/CollectionNameResolver.h b/arangod/Utils/CollectionNameResolver.h
index 343c37cfc7..b5792de67d 100644
--- a/arangod/Utils/CollectionNameResolver.h
+++ b/arangod/Utils/CollectionNameResolver.h
@@ -282,12 +282,12 @@ class CollectionNameResolver {
       auto it = _vocbase->_collectionsById.find(cid);
 
       if (it != _vocbase->_collectionsById.end()) {
-        if ((*it).second->_planId == 0) {
+        if ((*it).second->planId() == 0) {
           // DBserver local case
           name = (*it).second->name();
         } else {
           // DBserver case of a shard:
-          name = arangodb::basics::StringUtils::itoa((*it).second->_planId);
+          name = arangodb::basics::StringUtils::itoa((*it).second->planId());
           std::shared_ptr<CollectionInfo> ci =
               ClusterInfo::instance()->getCollection((*it).second->_dbName, name);
           name = ci->name();  // can be empty, if collection unknown
diff --git a/arangod/V8Server/v8-collection-util.cpp b/arangod/V8Server/v8-collection-util.cpp
index d4952561b3..4bc00901b6 100644
--- a/arangod/V8Server/v8-collection-util.cpp
+++ b/arangod/V8Server/v8-collection-util.cpp
@@ -51,9 +51,8 @@ void ReleaseCollection(TRI_vocbase_col_t const* collection) {
 
 TRI_vocbase_col_t* CoordinatorCollection(TRI_vocbase_t* vocbase,
                                          CollectionInfo const& ci) {
-  auto c = std::make_unique<TRI_vocbase_col_t>(vocbase, ci.type(), ci.id(), ci.name());
+  auto c = std::make_unique<TRI_vocbase_col_t>(vocbase, ci.type(), ci.id(), ci.name(), ci.id(), "");
   c->_isLocal = false;
-  c->_planId = ci.id();
   c->_status = ci.status();
 
   return c.release();
@@ -180,7 +179,7 @@ v8::Handle<v8::Object> WrapCollection(v8::Isolate* isolate,
     result->Set(_DbNameKey, TRI_V8_STRING(collection->dbName().c_str()));
     result->ForceSet(
         VersionKeyHidden,
-        v8::Integer::NewFromUnsigned(isolate, collection->_internalVersion),
+        v8::Integer::NewFromUnsigned(isolate, collection->internalVersion()),
         v8::DontEnum);
   }
 
diff --git a/arangod/V8Server/v8-collection.cpp b/arangod/V8Server/v8-collection.cpp
index 78785876c3..2334f3aac7 100644
--- a/arangod/V8Server/v8-collection.cpp
+++ b/arangod/V8Server/v8-collection.cpp
@@ -1211,7 +1211,6 @@ static void JS_PathVocbaseCol(v8::FunctionCallbackInfo<v8::Value> const& args) {
   }
 
   std::string const path(collection->path());
-
   v8::Handle<v8::Value> result = TRI_V8_STD_STRING(path);
 
   TRI_V8_RETURN(result);
@@ -1238,7 +1237,7 @@ static void JS_PlanIdVocbaseCol(
     TRI_V8_RETURN(V8CollectionId(isolate, collection->_cid));
   }
 
-  TRI_V8_RETURN(V8CollectionId(isolate, collection->_planId));
+  TRI_V8_RETURN(V8CollectionId(isolate, collection->planId()));
   TRI_V8_TRY_CATCH_END
 }
 
@@ -1566,7 +1565,7 @@ static void JS_RenameVocbaseCol(
   std::string const oldName(collection->_name);
 
   int res = TRI_RenameCollectionVocBase(collection->_vocbase, collection,
-                                        name.c_str(), doOverride, true);
+                                        name, doOverride, true);
 
   if (res != TRI_ERROR_NO_ERROR) {
     TRI_V8_THROW_EXCEPTION_MESSAGE(res, "cannot rename collection");
diff --git a/arangod/V8Server/v8-vocbase.cpp b/arangod/V8Server/v8-vocbase.cpp
index 25400e6a58..5f5d2f052d 100644
--- a/arangod/V8Server/v8-vocbase.cpp
+++ b/arangod/V8Server/v8-vocbase.cpp
@@ -1849,15 +1849,11 @@ static void MapGetVocBase(v8::Local<v8::String> const name,
       TRI_voc_cid_t cid;
       uint32_t internalVersion;
 
-      if (lock) {
-        READ_LOCKER(readLocker, collection->_lock);
+      {
+        CONDITIONAL_READ_LOCKER(readLocker, collection->_lock, lock);
         status = collection->_status;
         cid = collection->_cid;
-        internalVersion = collection->_internalVersion;
-      } else {
-        status = collection->_status;
-        cid = collection->_cid;
-        internalVersion = collection->_internalVersion;
+        internalVersion = collection->internalVersion();
       }
 
       // check if the collection is still alive
@@ -1963,7 +1959,7 @@ static void JS_PathDatabase(v8::FunctionCallbackInfo<v8::Value> const& args) {
     
   StorageEngine* engine = EngineSelectorFeature::ENGINE;
 
-  TRI_V8_RETURN_STD_STRING(engine->path(vocbase->_id));
+  TRI_V8_RETURN_STD_STRING(engine->databasePath(vocbase));
 }
 
 ////////////////////////////////////////////////////////////////////////////////
diff --git a/arangod/VocBase/collection.cpp b/arangod/VocBase/collection.cpp
index cc5112a193..48e8a020c2 100644
--- a/arangod/VocBase/collection.cpp
+++ b/arangod/VocBase/collection.cpp
@@ -1177,8 +1177,12 @@ static std::string GetCollectionDirectory(std::string const& path, TRI_voc_cid_t
 ////////////////////////////////////////////////////////////////////////////////
 
 TRI_collection_t* TRI_CreateCollection(
-    TRI_vocbase_t* vocbase, TRI_collection_t* collection, std::string const& path,
+    TRI_vocbase_t* vocbase, TRI_collection_t* collection, 
     arangodb::VocbaseCollectionInfo const& parameters) {
+  
+  StorageEngine* engine = EngineSelectorFeature::ENGINE;
+  std::string const path = engine->databasePath(vocbase);
+
   // sanity check
   if (sizeof(TRI_df_header_marker_t) + sizeof(TRI_df_footer_marker_t) >
       parameters.maximalSize()) {
@@ -1214,8 +1218,7 @@ TRI_collection_t* TRI_CreateCollection(
   }
 
   // use a temporary directory first. this saves us from leaving an empty
-  // directory
-  // behind, an the server refusing to start
+  // directory behind, and the server refusing to start
   std::string const tmpname = dirname + ".tmp";
 
   // create directory
@@ -1660,8 +1663,8 @@ void VocbaseCollectionInfo::setVersion(TRI_col_version_t version) {
   _version = version;
 }
 
-void VocbaseCollectionInfo::rename(char const* name) {
-  TRI_CopyString(_name, name, sizeof(_name) - 1);
+void VocbaseCollectionInfo::rename(std::string const& name) {
+  TRI_CopyString(_name, name.c_str(), sizeof(_name) - 1);
 }
 
 void VocbaseCollectionInfo::setRevision(TRI_voc_rid_t rid, bool force) {
@@ -1845,7 +1848,7 @@ void TRI_CreateVelocyPackCollectionInfo(
 /// function.
 ////////////////////////////////////////////////////////////////////////////////
 
-int TRI_RenameCollection(TRI_collection_t* collection, char const* name) {
+int TRI_RenameCollection(TRI_collection_t* collection, std::string const& name) {
   // Save name for rollback
   std::string oldName = collection->_info.name();
   collection->_info.rename(name);
@@ -1853,7 +1856,7 @@ int TRI_RenameCollection(TRI_collection_t* collection, char const* name) {
   int res = collection->_info.saveToFile(collection->path(), true);
   if (res != TRI_ERROR_NO_ERROR) {
     // Rollback
-    collection->_info.rename(oldName.c_str());
+    collection->_info.rename(oldName);
   }
 
   return res;
diff --git a/arangod/VocBase/collection.h b/arangod/VocBase/collection.h
index 53cf3e2aa8..47fec51e7c 100644
--- a/arangod/VocBase/collection.h
+++ b/arangod/VocBase/collection.h
@@ -214,7 +214,7 @@ class VocbaseCollectionInfo {
 
   // Changes the name. Should only be called by TRI_RenameCollection
   // Use with caution!
-  void rename(char const*);
+  void rename(std::string const&);
 
   void setIsSystem(bool value) { _isSystem = value; }
 
@@ -355,7 +355,6 @@ struct TRI_collection_t {
 ////////////////////////////////////////////////////////////////////////////////
 
 TRI_collection_t* TRI_CreateCollection(TRI_vocbase_t*, TRI_collection_t*,
-                                       std::string const& path,
                                        arangodb::VocbaseCollectionInfo const&);
 
 ////////////////////////////////////////////////////////////////////////////////
@@ -387,7 +386,7 @@ void TRI_CreateVelocyPackCollectionInfo(arangodb::VocbaseCollectionInfo const&,
 /// @brief renames a collection
 ////////////////////////////////////////////////////////////////////////////////
 
-int TRI_RenameCollection(TRI_collection_t*, char const*);
+int TRI_RenameCollection(TRI_collection_t*, std::string const&);
 
 ////////////////////////////////////////////////////////////////////////////////
 /// @brief iterates over a collection
diff --git a/arangod/VocBase/document-collection.cpp b/arangod/VocBase/document-collection.cpp
index f5b4685fef..9b38fb79e7 100644
--- a/arangod/VocBase/document-collection.cpp
+++ b/arangod/VocBase/document-collection.cpp
@@ -1185,7 +1185,7 @@ static int IterateMarkersCollection(arangodb::Transaction* trx,
 ////////////////////////////////////////////////////////////////////////////////
 
 TRI_document_collection_t* TRI_CreateDocumentCollection(
-    TRI_vocbase_t* vocbase, std::string const& path, VocbaseCollectionInfo& parameters,
+    TRI_vocbase_t* vocbase, VocbaseCollectionInfo& parameters,
     TRI_voc_cid_t cid) {
   if (cid > 0) {
     TRI_UpdateTickServer(cid);
@@ -1231,7 +1231,7 @@ TRI_document_collection_t* TRI_CreateDocumentCollection(
   document->_keyGenerator = keyGenerator;
 
   TRI_collection_t* collection =
-      TRI_CreateCollection(vocbase, document, path, parameters);
+      TRI_CreateCollection(vocbase, document, parameters);
 
   if (collection == nullptr) {
     delete document;
diff --git a/arangod/VocBase/document-collection.h b/arangod/VocBase/document-collection.h
index 744714dbb3..9fa2736348 100644
--- a/arangod/VocBase/document-collection.h
+++ b/arangod/VocBase/document-collection.h
@@ -327,7 +327,7 @@ struct TRI_document_collection_t : public TRI_collection_t {
 ////////////////////////////////////////////////////////////////////////////////
 
 TRI_document_collection_t* TRI_CreateDocumentCollection(
-    TRI_vocbase_t*, std::string const&, arangodb::VocbaseCollectionInfo&,
+    TRI_vocbase_t*, arangodb::VocbaseCollectionInfo&,
     TRI_voc_cid_t);
 
 ////////////////////////////////////////////////////////////////////////////////
diff --git a/arangod/VocBase/replication-applier.cpp b/arangod/VocBase/replication-applier.cpp
index cf7183506a..99da4063ad 100644
--- a/arangod/VocBase/replication-applier.cpp
+++ b/arangod/VocBase/replication-applier.cpp
@@ -82,7 +82,7 @@ static int ReadTick(VPackSlice const& slice, char const* attributeName,
 
 static std::string GetConfigurationFilename(TRI_vocbase_t* vocbase) {
   StorageEngine* engine = EngineSelectorFeature::ENGINE;
-  return arangodb::basics::FileUtils::buildFilename(engine->path(vocbase->_id), "REPLICATION-APPLIER-CONFIG");
+  return arangodb::basics::FileUtils::buildFilename(engine->databasePath(vocbase), "REPLICATION-APPLIER-CONFIG");
 }
 
 ////////////////////////////////////////////////////////////////////////////////
@@ -298,7 +298,7 @@ static int LoadConfiguration(TRI_vocbase_t* vocbase,
 
 static std::string GetStateFilename(TRI_vocbase_t* vocbase) {
   StorageEngine* engine = EngineSelectorFeature::ENGINE;
-  return arangodb::basics::FileUtils::buildFilename(engine->path(vocbase->_id), "REPLICATION-APPLIER-STATE");
+  return arangodb::basics::FileUtils::buildFilename(engine->databasePath(vocbase), "REPLICATION-APPLIER-STATE");
 }
 
 ////////////////////////////////////////////////////////////////////////////////
diff --git a/arangod/VocBase/vocbase.cpp b/arangod/VocBase/vocbase.cpp
index 04b81b2dbb..9829ec192f 100644
--- a/arangod/VocBase/vocbase.cpp
+++ b/arangod/VocBase/vocbase.cpp
@@ -93,10 +93,11 @@ enum DropState {
 ////////////////////////////////////////////////////////////////////////////////
 
 TRI_vocbase_col_t::TRI_vocbase_col_t(TRI_vocbase_t* vocbase, TRI_col_type_e type,
-                                     TRI_voc_cid_t cid, std::string const& name) 
+                                     TRI_voc_cid_t cid, std::string const& name,
+                                     TRI_voc_cid_t planId, std::string const& path) 
     : _vocbase(vocbase),
       _cid(cid),
-      _planId(0),
+      _planId(planId),
       _type(static_cast<TRI_col_type_t>(type)),
       _internalVersion(0),
       _lock(),
@@ -104,6 +105,7 @@ TRI_vocbase_col_t::TRI_vocbase_col_t(TRI_vocbase_t* vocbase, TRI_col_type_e type
       _collection(nullptr),
       _dbName(vocbase->name()),
       _name(name),
+      _path(path),
       _isLocal(true),
       _canDrop(true),
       _canUnload(true),
@@ -408,66 +410,69 @@ static bool DropCollectionCallback(TRI_collection_t* col, void* data) {
   return true;
 }
 
-////////////////////////////////////////////////////////////////////////////////
 /// @brief adds a new collection
-///
-/// Caller must hold _collectionsLock in write mode
-////////////////////////////////////////////////////////////////////////////////
-
-static TRI_vocbase_col_t* AddCollection(TRI_vocbase_t* vocbase,
-                                        TRI_col_type_e type, TRI_voc_cid_t cid,
-                                        std::string const& name) {
+/// caller must hold _collectionsLock in write mode or set doLock
+TRI_vocbase_col_t* TRI_AddCollectionVocBase(bool doLock,
+                                            TRI_vocbase_t* vocbase,
+                                            TRI_col_type_e type, TRI_voc_cid_t cid,
+                                            std::string const& name,
+                                            TRI_voc_cid_t planId,
+                                            std::string const& path) {
   // create a new proxy
   auto collection =
-      std::make_unique<TRI_vocbase_col_t>(vocbase, type, cid, name);
+      std::make_unique<TRI_vocbase_col_t>(vocbase, type, cid, name, planId, path);
 
-  TRI_ASSERT(collection != nullptr);
+  {
+    CONDITIONAL_WRITE_LOCKER(writeLocker, vocbase->_collectionsLock, doLock);
 
-  // check name
-  auto it = vocbase->_collectionsByName.emplace(name, collection.get());
+    // check name
+    auto it = vocbase->_collectionsByName.emplace(name, collection.get());
 
-  if (!it.second) {
-    LOG(ERR) << "duplicate entry for collection name '" << name << "'";
-    LOG(ERR) << "collection id " << cid
-             << " has same name as already added collection "
-             << vocbase->_collectionsByName[name]->_cid;
+    if (!it.second) {
+      LOG(ERR) << "duplicate entry for collection name '" << name << "'";
+      LOG(ERR) << "collection id " << cid
+              << " has same name as already added collection "
+              << vocbase->_collectionsByName[name]->_cid;
 
-    TRI_set_errno(TRI_ERROR_ARANGO_DUPLICATE_NAME);
-
-    return nullptr;
-  }
-
-  // check collection identifier
-  TRI_ASSERT(collection->_cid == cid);
-  try {
-    auto it2 = vocbase->_collectionsById.emplace(cid, collection.get());
-
-    if (!it2.second) {
-      vocbase->_collectionsByName.erase(name);
-
-      LOG(ERR) << "duplicate collection identifier " << collection->_cid
-               << " for name '" << name << "'";
-
-      TRI_set_errno(TRI_ERROR_ARANGO_DUPLICATE_IDENTIFIER);
+      TRI_set_errno(TRI_ERROR_ARANGO_DUPLICATE_NAME);
 
       return nullptr;
     }
-  }
-  catch (...) {
-    vocbase->_collectionsByName.erase(name);
-    return nullptr;
+
+    // check collection identifier
+    TRI_ASSERT(collection->_cid == cid);
+    try {
+      auto it2 = vocbase->_collectionsById.emplace(cid, collection.get());
+
+      if (!it2.second) {
+        vocbase->_collectionsByName.erase(name);
+
+        LOG(ERR) << "duplicate collection identifier " << collection->_cid
+                << " for name '" << name << "'";
+
+        TRI_set_errno(TRI_ERROR_ARANGO_DUPLICATE_IDENTIFIER);
+
+        return nullptr;
+      }
+    }
+    catch (...) {
+      vocbase->_collectionsByName.erase(name);
+      return nullptr;
+    }
+
+    TRI_ASSERT(vocbase->_collectionsByName.size() == vocbase->_collectionsById.size());
+
+    try {
+      vocbase->_collections.emplace_back(collection.get());
+    }
+    catch (...) {
+      vocbase->_collectionsByName.erase(name);
+      vocbase->_collectionsById.erase(cid);
+      return nullptr;
+    }
   }
 
-  TRI_ASSERT(vocbase->_collectionsByName.size() == vocbase->_collectionsById.size());
-
-  try {
-    vocbase->_collections.emplace_back(collection.get());
-  }
-  catch (...) {
-    vocbase->_collectionsByName.erase(name);
-    vocbase->_collectionsById.erase(cid);
-    return nullptr;
-  }
+  collection->_status = TRI_VOC_COL_STATUS_UNLOADED;
 
   return collection.release();
 }
@@ -504,27 +509,22 @@ static TRI_vocbase_col_t* CreateCollection(
     return nullptr;
   }
 
-  // .............................................................................
   // ok, construct the collection
-  // .............................................................................
-  
-  StorageEngine* engine = EngineSelectorFeature::ENGINE;
-
   TRI_document_collection_t* document =
-      TRI_CreateDocumentCollection(vocbase, engine->path(vocbase->_id), parameters, cid);
+      TRI_CreateDocumentCollection(vocbase, parameters, cid);
 
   if (document == nullptr) {
     return nullptr;
   }
 
   TRI_collection_t* col = document;
-
-  // add collection container
   TRI_vocbase_col_t* collection = nullptr;
+  TRI_voc_cid_t planId = parameters.planId();
+  col->_info.setPlanId(planId);
 
   try {
     collection =
-        AddCollection(vocbase, col->_info.type(), col->_info.id(), col->_info.name());
+        TRI_AddCollectionVocBase(ConditionalWriteLocker::DoNotLock(), vocbase, col->_info.type(), col->_info.id(), col->_info.name(), planId, col->path());
   } catch (...) {
     // if an exception is caught, collection will be a nullptr
   }
@@ -536,11 +536,6 @@ static TRI_vocbase_col_t* CreateCollection(
     return nullptr;
   }
 
-  if (parameters.planId() > 0) {
-    collection->_planId = parameters.planId();
-    col->_info.setPlanId(parameters.planId());
-  }
-
   // cid might have been assigned
   cid = col->_info.id();
 
@@ -559,8 +554,8 @@ static TRI_vocbase_col_t* CreateCollection(
 ////////////////////////////////////////////////////////////////////////////////
 
 static int RenameCollection(TRI_vocbase_t* vocbase,
-                            TRI_vocbase_col_t* collection, char const* oldName,
-                            char const* newName) {
+                            TRI_vocbase_col_t* collection, std::string const& oldName,
+                            std::string const& newName) {
   // cannot rename a corrupted collection
   if (collection->_status == TRI_VOC_COL_STATUS_CORRUPTED) {
     return TRI_set_errno(TRI_ERROR_ARANGO_CORRUPTED_COLLECTION);
@@ -986,11 +981,6 @@ static bool FilenameStringComparator(std::string const& lhs,
   return numLeft < numRight;
 }
   
-std::string TRI_vocbase_col_t::path() const {
-  StorageEngine* engine = EngineSelectorFeature::ENGINE;
-  return engine->path(_vocbase->_id, _cid);
-}
-
 void TRI_vocbase_col_t::toVelocyPack(VPackBuilder& builder, bool includeIndexes,
                                      TRI_voc_tick_t maxTick) {
   TRI_ASSERT(!builder.isClosed());
@@ -1265,14 +1255,9 @@ char const* TRI_GetStatusStringCollectionVocBase(
   }
 }
 
-////////////////////////////////////////////////////////////////////////////////
 /// @brief gets a collection name by a collection id
-///
-/// The name is fetched under a lock to make this thread-safe. Returns NULL if
-/// the collection does not exist. It is the caller's responsibility to free the
-/// name returned
-////////////////////////////////////////////////////////////////////////////////
-
+/// the name is fetched under a lock to make this thread-safe.
+/// returns empty string if the collection does not exist.
 std::string TRI_GetCollectionNameByIdVocBase(TRI_vocbase_t* vocbase,
                                              TRI_voc_cid_t id) {
   READ_LOCKER(readLocker, vocbase->_collectionsLock);
@@ -1533,7 +1518,7 @@ int TRI_DropCollectionVocBase(TRI_vocbase_t* vocbase,
 
 int TRI_RenameCollectionVocBase(TRI_vocbase_t* vocbase,
                                 TRI_vocbase_col_t* collection,
-                                char const* newName, bool doOverride,
+                                std::string const& newName, bool doOverride,
                                 bool writeMarker) {
   if (!collection->_canRename) {
     return TRI_set_errno(TRI_ERROR_FORBIDDEN);
@@ -1549,7 +1534,7 @@ int TRI_RenameCollectionVocBase(TRI_vocbase_t* vocbase,
   // old name should be different
 
   // check if names are actually different
-  if (oldName == std::string(newName)) {
+  if (oldName == newName) {
     return TRI_ERROR_NO_ERROR;
   }
 
@@ -1576,7 +1561,7 @@ int TRI_RenameCollectionVocBase(TRI_vocbase_t* vocbase,
 
   TRI_EVENTUAL_WRITE_LOCK_STATUS_VOCBASE_COL(collection);
 
-  int res = RenameCollection(vocbase, collection, oldName.c_str(), newName);
+  int res = RenameCollection(vocbase, collection, oldName, newName);
 
   TRI_WRITE_UNLOCK_STATUS_VOCBASE_COL(collection);
 
@@ -1860,7 +1845,7 @@ TRI_vocbase_t::~TRI_vocbase_t() {
   
 std::string const TRI_vocbase_t::path() {
   StorageEngine* engine = EngineSelectorFeature::ENGINE;
-  return engine->path(_id);
+  return engine->databasePath(this);
 }
 
 /// @brief checks if a database name is allowed
diff --git a/arangod/VocBase/vocbase.h b/arangod/VocBase/vocbase.h
index 708619d583..7b8e33abf3 100644
--- a/arangod/VocBase/vocbase.h
+++ b/arangod/VocBase/vocbase.h
@@ -343,12 +343,12 @@ class TRI_vocbase_col_t {
   TRI_vocbase_col_t() = delete;
 
   TRI_vocbase_col_t(TRI_vocbase_t* vocbase, TRI_col_type_e type,
-                    TRI_voc_cid_t cid, std::string const& name);
+                    TRI_voc_cid_t cid, std::string const& name, TRI_voc_cid_t planId,
+                    std::string const& path);
   ~TRI_vocbase_col_t();
 
   // Leftover from struct
  public:
-  std::string path() const;
   TRI_vocbase_t* vocbase() const { return _vocbase; }
   TRI_voc_cid_t cid() const { return _cid; }
   TRI_voc_cid_t planId() const { return _planId; }
@@ -356,6 +356,7 @@ class TRI_vocbase_col_t {
   uint32_t internalVersion() const { return _internalVersion; }
   std::string const& dbName() const { return _dbName; }
   std::string name() const { return _name; }
+  std::string const& path() const { return _path; }
   bool isLocal() const { return _isLocal; }
   bool canDrop() const { return _canDrop; }
   bool canUnload() const { return _canUnload; }
@@ -393,20 +394,22 @@ class TRI_vocbase_col_t {
 
  public:
   TRI_vocbase_t* _vocbase;
-
-  TRI_voc_cid_t _cid;     // local collecttion identifier
+  TRI_voc_cid_t const _cid;     // local collection identifier
+ private:
   TRI_voc_cid_t _planId;  // cluster-wide collection identifier
+ public:
   TRI_col_type_t _type;   // collection type
   uint32_t _internalVersion;  // is incremented when a collection is renamed
-
-  arangodb::basics::ReadWriteLock _lock;  // lock protecting the status and name
-
   // this is used to prevent caching of collection objects
   // with "wrong" names in the "db" object
+ public:
+  arangodb::basics::ReadWriteLock _lock;  // lock protecting the status and name
+
   TRI_vocbase_col_status_e _status;  // status of the collection
   TRI_document_collection_t* _collection;  // NULL or pointer to loaded collection
   std::string const _dbName;  // name of the database
   std::string _name;          // name of the collection
+  std::string const _path;    // storage path
 
   bool _isLocal;    // if true, the collection is local. if false,
                     // the collection is a remote (cluster) collection
@@ -449,15 +452,19 @@ std::shared_ptr<arangodb::velocypack::Builder> TRI_InventoryCollectionsVocBase(
 
 char const* TRI_GetStatusStringCollectionVocBase(TRI_vocbase_col_status_e);
 
-////////////////////////////////////////////////////////////////////////////////
-/// @brief get a collection name by a collection id
-///
-/// the name is fetched under a lock to make this thread-safe. returns NULL if
-/// the collection does not exist
-/// it is the caller's responsibility to free the name returned
-////////////////////////////////////////////////////////////////////////////////
+/// @brief adds a new collection
+/// caller must hold _collectionsLock in write mode or set doLock
+TRI_vocbase_col_t* TRI_AddCollectionVocBase(bool doLock,
+                                            TRI_vocbase_t* vocbase,
+                                            TRI_col_type_e type, TRI_voc_cid_t cid,
+                                            std::string const& name,
+                                            TRI_voc_cid_t planId,
+                                            std::string const& path);
 
-std::string TRI_GetCollectionNameByIdVocBase(TRI_vocbase_t*, const TRI_voc_cid_t);
+/// @brief get a collection name by a collection id
+/// the name is fetched under a lock to make this thread-safe.
+/// returns empty string if the collection does not exist.
+std::string TRI_GetCollectionNameByIdVocBase(TRI_vocbase_t*, TRI_voc_cid_t);
 
 ////////////////////////////////////////////////////////////////////////////////
 /// @brief looks up a (document) collection by name
@@ -497,7 +504,7 @@ int TRI_DropCollectionVocBase(TRI_vocbase_t*, TRI_vocbase_col_t*, bool);
 /// @brief renames a (document) collection
 ////////////////////////////////////////////////////////////////////////////////
 
-int TRI_RenameCollectionVocBase(TRI_vocbase_t*, TRI_vocbase_col_t*, char const*,
+int TRI_RenameCollectionVocBase(TRI_vocbase_t*, TRI_vocbase_col_t*, std::string const&,
                                 bool, bool);
 
 ////////////////////////////////////////////////////////////////////////////////
diff --git a/arangod/Wal/RecoverState.cpp b/arangod/Wal/RecoverState.cpp
index b8fed40490..b007d191ec 100644
--- a/arangod/Wal/RecoverState.cpp
+++ b/arangod/Wal/RecoverState.cpp
@@ -604,7 +604,7 @@ bool RecoverState::ReplayMarker(TRI_df_marker_t const* marker, void* data,
         }
 
         int res =
-            TRI_RenameCollectionVocBase(vocbase, collection, name.c_str(), true, false);
+            TRI_RenameCollectionVocBase(vocbase, collection, name, true, false);
 
         if (res != TRI_ERROR_NO_ERROR) {
           LOG(WARN) << "cannot rename collection " << collectionId << " in database " << databaseId << " to '" << name << "': " << TRI_errno_string(res);
diff --git a/lib/Basics/ReadLocker.h b/lib/Basics/ReadLocker.h
index 3310c25d1c..88bcd40924 100644
--- a/lib/Basics/ReadLocker.h
+++ b/lib/Basics/ReadLocker.h
@@ -287,6 +287,9 @@ class ConditionalReadLocker {
     }
     return false;
   }
+  
+  static constexpr bool DoLock() { return true; }
+  static constexpr bool DoNotLock() { return false; }
 
  private:
   //////////////////////////////////////////////////////////////////////////////
diff --git a/lib/Basics/WriteLocker.h b/lib/Basics/WriteLocker.h
index fe201a9ce5..fd42bc0c6f 100644
--- a/lib/Basics/WriteLocker.h
+++ b/lib/Basics/WriteLocker.h
@@ -58,6 +58,8 @@
 
 #define TRY_WRITE_LOCKER(obj, lock) arangodb::basics::TryWriteLocker obj(&lock)
 
+#define CONDITIONAL_WRITE_LOCKER(obj, lock, condition) arangodb::basics::ConditionalWriteLocker obj(&lock, (condition))
+
 namespace arangodb {
 namespace basics {
 
@@ -183,7 +185,7 @@ class TryWriteLocker {
 
  public:
   ////////////////////////////////////////////////////////////////////////////////
-  /// @brief tries to aquire a write-lock
+  /// @brief tries to acquire a write-lock
   ///
   /// The constructor tries to aquire a write lock, the destructors unlocks the
   /// lock if we acquired it in the constructor
@@ -236,6 +238,73 @@ class TryWriteLocker {
 
   bool _isLocked;
 };
+
+class ConditionalWriteLocker {
+  ConditionalWriteLocker(ConditionalWriteLocker const&) = delete;
+  ConditionalWriteLocker& operator=(ConditionalWriteLocker const&) = delete;
+
+ public:
+  ////////////////////////////////////////////////////////////////////////////////
+  /// @brief acquire a write-lock
+  ///
+  /// The constructor tries to write-lock the lock, the destructor unlocks the
+  /// lock if it was acquired in the constructor
+  ////////////////////////////////////////////////////////////////////////////////
+
+  ConditionalWriteLocker(ReadWriteLock* readWriteLock, bool condition)
+      : _readWriteLock(readWriteLock), _isLocked(false) {
+    if (condition) {
+      _readWriteLock->writeLock();
+      _isLocked = true;
+    }
+  }
+
+  //////////////////////////////////////////////////////////////////////////////
+  /// @brief releases the write-lock
+  //////////////////////////////////////////////////////////////////////////////
+
+  ~ConditionalWriteLocker() {
+    if (_isLocked) {
+      _readWriteLock->unlock();
+    }
+  }
+
+  //////////////////////////////////////////////////////////////////////////////
+  /// @brief whether or not we acquired the lock
+  //////////////////////////////////////////////////////////////////////////////
+
+  bool isLocked() const { return _isLocked; }
+  
+  //////////////////////////////////////////////////////////////////////////////
+  /// @brief unlocks the read-write lock
+  //////////////////////////////////////////////////////////////////////////////
+
+  bool unlock() {
+    if (_isLocked) {
+      _readWriteLock->unlock();
+      _isLocked = false;
+      return true;
+    }
+    return false;
+  }
+
+  static constexpr bool DoLock() { return true; }
+  static constexpr bool DoNotLock() { return false; }
+
+ private:
+  //////////////////////////////////////////////////////////////////////////////
+  /// @brief the read-write lock
+  //////////////////////////////////////////////////////////////////////////////
+
+  ReadWriteLock* _readWriteLock;
+
+  //////////////////////////////////////////////////////////////////////////////
+  /// @brief whether or not we acquired the lock
+  //////////////////////////////////////////////////////////////////////////////
+
+  bool _isLocked;
+};
+
 }
 }