diff --git a/hbs2-storage-ncq/lib/HBS2/Storage/NCQ2.hs b/hbs2-storage-ncq/lib/HBS2/Storage/NCQ2.hs
index 9c994dc3..6a4a537b 100644
--- a/hbs2-storage-ncq/lib/HBS2/Storage/NCQ2.hs
+++ b/hbs2-storage-ncq/lib/HBS2/Storage/NCQ2.hs
@@ -137,6 +137,8 @@ data NCQStorage2 =
   , ncqStorageSyncReq :: TVar Bool
   , ncqSyncNo         :: TVar Int
   , ncqTrackedFiles   :: TVar (HashPSQ FileKey FilePrio (Maybe CachedEntry))
+  , ncqFilesUsage     :: TVar (HashMap FileKey Int)
+  , ncqFilesToRemove  :: TVar (HashSet FileKey)
   , ncqCachedEntries  :: TVar Int
   , ncqWrites         :: TVar Int
   , ncqWriteEMA       :: TVar Double  -- for writes-per-seconds
@@ -165,6 +167,8 @@ ncqStorageOpen2 fp upd = do
   ncqStorageSyncReq  <- newTVarIO False
   ncqSyncNo          <- newTVarIO 0
   ncqTrackedFiles    <- newTVarIO HPSQ.empty
+  ncqFilesUsage      <- newTVarIO mempty
+  ncqFilesToRemove   <- newTVarIO mempty
   ncqCachedEntries   <- newTVarIO 0
   ncqStorageTasks    <- newTVarIO 0
   ncqWrites          <- newTVarIO 0
@@ -279,12 +283,23 @@ ncqLocate2 ncq@NCQStorage2{..} href = flip runContT pure $ callCC \exit -> do
 
   lift (ncqLookupEntry ncq href) >>= maybe none (exit . Just . InMemory . coerce)
 
-  -- atomically $ modifyTVar' ncqWrites succ
+  atomically $ modifyTVar' ncqWrites succ
 
   -- FIXME: race
   --   merge can-delete-file-while-in-use
 
-  tracked <- readTVarIO ncqTrackedFiles <&> HPSQ.toList
+  tracked <- atomically do
+               fs <- readTVar ncqTrackedFiles <&> HPSQ.toList
+               for_ fs $ \(k,_,_) -> modifyTVar ncqFilesUsage (HM.insertWith (+) k 1)
+               pure fs
+
+  let sweep = \case
+        Nothing -> Nothing
+        Just v | v <= 0 -> Nothing
+        Just v -> Just (pred v)
+
+  ContT $ bracket none $ const $ atomically do
+    for_ tracked $ \(k,_,_) -> modifyTVar ncqFilesUsage (HM.alter sweep k)
 
   for_ tracked $ \(fk, prio, mCached) -> do
     case mCached of
@@ -377,6 +392,35 @@ ncqStorageRun2 ncq@NCQStorage2{..} = flip runContT pure do
                 ncqAlterEntrySTM ncq (coerce k) (const Nothing)
         loop
 
+  spawnActivity $ forever do
+    rmz <- atomically do
+      rms   <- readTVar ncqFilesToRemove <&> HS.toList
+      usage <- readTVar ncqFilesUsage
+
+      what <- for rms $ \k -> do
+            if fromMaybe 0 (HM.lookup k usage) <= 0 then
+              pure (Right k)
+            else
+              pure (Left k)
+
+      let r = rights what
+      let l = lefts what
+
+      when (List.null r) STM.retry
+
+      writeTVar ncqFilesToRemove (HS.fromList l)
+
+      pure r
+
+    for_ rmz $ \k -> do
+      let d = ncqGetFileName ncq (toFileName (DataFile k))
+      let i = ncqGetFileName ncq (toFileName (IndexFile k))
+
+      debug $ red "remove" <+> pretty d
+      debug $ red "remove" <+> pretty i
+
+      rm d >> rm i
+
   spawnActivity $ forever (liftIO $ join $ atomically (readTQueue ncqJobQ))
 
   spawnActivity measureWPS
@@ -677,7 +721,19 @@ ncqRepair me@NCQStorage2{} = do
 
   for_ fossils $ \fo -> liftIO $ flip fix 0 \next i -> do
     let dataFile = ncqGetFileName me $ toFileName (DataFile fo)
+
+    stat <- liftIO $ PFS.getFileStatus dataFile
+    -- FIXME: maybe-creation-time-actually
+    let ts = PFS.modificationTimeHiRes stat
+
     try @_ @SomeException (ncqFileFastCheck dataFile) >>= \case
+
+      _ | ts == 0 -> do
+
+        warn $ red "remove obsolete files" <+> pretty fo
+        rm dataFile
+        rm (ncqGetFileName me (toFileName (IndexFile fo)))
+
       Left e -> do
         err (viaShow e)
         -- TODO: try-fix-later
@@ -818,13 +874,15 @@ ncqStorageMergeStep ncq@NCQStorage2{..}  = ncqRunTask ncq False $ flip runContT
                     pure $ Just (ts,fk)
 
           atomically do
-            modifyTVar ncqTrackedFiles (HPSQ.delete a)
-            modifyTVar ncqTrackedFiles (HPSQ.delete b)
+            for_ [a,b] $ \x -> do
+              modifyTVar ncqTrackedFiles (HPSQ.delete x)
+              modifyTVar ncqFilesToRemove (HS.insert x)
+
             for_ idx $ \(ts,fk) -> do
               ncqAddTrackedFileSTM ncq (coerce fk) (posixToTimeSpec ts)
 
-          mapM_ rm [fDataNameA, fDataNameB, fIndexNameB, fIndexNameA]
-
+          for_ [fDataNameA, fDataNameB, fIndexNameB, fIndexNameA] $ \fn -> do
+            setFileTimesHiRes fn 0 0
 
     orFail what e = do
       r <- what