code: void removeUnreadableSSTables(File directory)
      {
          View currentView, newView;
          Set<SSTableReader> remaining = new HashSet<>();
          do
          {
              currentView = view.get();
              for (SSTableReader r : currentView.nonCompactingSStables())
                  if (!r.descriptor.directory.equals(directory))
                      remaining.add(r);
  
              if (remaining.size() == currentView.nonCompactingSStables().size())
                  return;
  
              newView = currentView.replace(currentView.sstables, remaining);
          }
          while (!view.compareAndSet(currentView, newView));
          for (SSTableReader sstable : currentView.sstables)
              if (!remaining.contains(sstable))
                  sstable.selfRef().release();
          notifySSTablesChanged(remaining, Collections.<SSTableReader>emptySet(), OperationType.UNKNOWN);
      }
docs: Removes every SSTable in the directory from the DataTracker's view.
  @param directory the unreadable directory, possibly with SSTables in it, but not necessarily.