diff --git a/python/ray/tune/durable_trainable.py b/python/ray/tune/durable_trainable.py
index d48053bab1512..150d98c6b9323 100644
--- a/python/ray/tune/durable_trainable.py
+++ b/python/ray/tune/durable_trainable.py
@@ -12,6 +12,11 @@ class DurableTrainable(Trainable):
     """A fault-tolerant Trainable.
 
     Supports checkpointing to and restoring from remote storage.
+
+    The storage client must provide durability for restoration to work. That
+    is, once ``storage.client.wait()`` returns after a checkpoint `sync up`,
+    the checkpoint is considered committed and can be used to restore the
+    trainable.
     """
 
     def __init__(self, *args, **kwargs):
@@ -34,6 +39,7 @@ def restore(self, checkpoint_path):
         if not os.path.exists(local_dirpath):
             os.makedirs(local_dirpath)
         self.storage_client.sync_down(storage_dirpath, local_dirpath)
+        self.storage_client.wait()
         super(DurableTrainable, self).restore(checkpoint_path)
 
     def delete_checkpoint(self, checkpoint_path):
@@ -43,9 +49,13 @@ def delete_checkpoint(self, checkpoint_path):
         self.storage_client.delete(self._storage_path(local_dirpath))
 
     def _storage_path(self, local_path):
-        rel_local_path = os.path.relpath(local_path, self.logdir)
+        logdir_parent = os.path.dirname(self.logdir)
+        rel_local_path = os.path.relpath(local_path, logdir_parent)
         return os.path.join(self._root_storage_path(), rel_local_path)
 
     def _root_storage_path(self):
-        """Path to directory in which checkpoints and logs are stored."""
+        """Path to directory in which checkpoints are stored.
+
+        You can also use `self.storage_client` to store logs here.
+        """
         raise NotImplementedError("Storage path must be provided by subclass.")
diff --git a/python/ray/tune/ray_trial_executor.py b/python/ray/tune/ray_trial_executor.py
index c9efee0e8d971..368a26a510a8e 100644
--- a/python/ray/tune/ray_trial_executor.py
+++ b/python/ray/tune/ray_trial_executor.py
@@ -148,9 +148,11 @@ def _start_trial(self, trial, checkpoint=None, runner=None):
         """
         prior_status = trial.status
         self.set_status(trial, Trial.RUNNING)
-        trial.set_runner(runner or self._setup_remote_runner(
-            trial,
-            reuse_allowed=checkpoint is not None or trial.has_checkpoint()))
+        trial.set_runner(
+            runner or self._setup_remote_runner(
+                trial,
+                reuse_allowed=checkpoint is not None
+                or trial.has_checkpoint()))
         self.restore(trial, checkpoint)
 
         previous_run = self._find_item(self._paused, trial)
@@ -208,7 +210,7 @@ def start_trial(self, trial, checkpoint=None):
             checkpoint (Checkpoint): A Python object or path storing the state
                 of trial.
         """
-        attempts = trial.num_failures_between_results
+        attempts = trial.num_failures_since_result
         if attempts >= TRIAL_START_ATTEMPTS:
             return  # Exceeded restoration attempts.
         self._commit_resources(trial.resources)
diff --git a/python/ray/tune/sync_client.py b/python/ray/tune/sync_client.py
index 6c10053c1bc16..a62284d5abd4b 100644
--- a/python/ray/tune/sync_client.py
+++ b/python/ray/tune/sync_client.py
@@ -29,7 +29,16 @@ def noop(*args):
 
 
 def get_sync_client(sync_function, delete_function=None):
-    """Gets sync client."""
+    """Returns a sync client.
+
+    Args:
+        sync_function (str|function): Sync function.
+        delete_function (Optional[str|function]): Delete function. Must be
+            the same type as sync_function if it is provided.
+
+    Raises:
+        ValueError if sync_function or delete_function are malformed.
+    """
     if delete_function and type(sync_function) != type(delete_function):
         raise ValueError("Sync and delete functions must be of same type.")
     if isinstance(sync_function, types.FunctionType):
@@ -45,6 +54,14 @@ def get_sync_client(sync_function, delete_function=None):
 
 
 def get_cloud_sync_client(remote_path):
+    """Returns a CommandBasedClient that can sync to/from remote storage.
+
+    Args:
+        remote_path (str): Path to remote storage (S3 or GS).
+
+    Raises:
+        ValueError if malformed remote_dir.
+    """
     if remote_path.startswith(S3_PREFIX):
         if not distutils.spawn.find_executable("aws"):
             raise ValueError(
@@ -67,20 +84,24 @@ def get_cloud_sync_client(remote_path):
 
 class SyncClient(object):
     def sync_up(self, source, target):
-        """Sync up from source to target.
+        """Syncs up from source to target.
+
         Args:
             source (str): Source path.
             target (str): Target path.
+
         Returns:
             True if sync initiation successful, False otherwise.
         """
         raise NotImplementedError
 
     def sync_down(self, source, target):
-        """Sync down from source to target.
+        """Syncs down from source to target.
+
         Args:
             source (str): Source path.
             target (str): Target path.
+
         Returns:
             True if sync initiation successful, False otherwise.
         """
@@ -98,7 +119,7 @@ def delete(self, target):
         raise NotImplementedError
 
     def wait(self):
-        """Wait for current sync to complete, if asynchronously started."""
+        """Waits for current sync to complete, if asynchronously started."""
         pass
 
     def reset(self):
diff --git a/python/ray/tune/syncer.py b/python/ray/tune/syncer.py
index f442a8288c1e4..0c5f333a9bd76 100644
--- a/python/ray/tune/syncer.py
+++ b/python/ray/tune/syncer.py
@@ -221,6 +221,9 @@ def get_cloud_syncer(local_dir, remote_dir=None, sync_function=None):
             remote_dir. If string, then it must be a string template for
             syncer to run. If not provided, it defaults
             to standard S3 or gsutil sync commands.
+
+    Raises:
+        ValueError if malformed remote_dir.
     """
     key = (local_dir, remote_dir)
 
diff --git a/python/ray/tune/tests/test_checkpoint_manager.py b/python/ray/tune/tests/test_checkpoint_manager.py
index 4567db6c15a36..7085cecdce40c 100644
--- a/python/ray/tune/tests/test_checkpoint_manager.py
+++ b/python/ray/tune/tests/test_checkpoint_manager.py
@@ -21,8 +21,8 @@ def mock_result(i):
         return {"i": i}
 
     def checkpoint_manager(self, keep_checkpoints_num):
-        return CheckpointManager(keep_checkpoints_num, "i",
-                                 delete_fn=lambda c: None)
+        return CheckpointManager(
+            keep_checkpoints_num, "i", delete_fn=lambda c: None)
 
     def testOnCheckpointOrdered(self):
         """
diff --git a/python/ray/tune/tests/test_ray_trial_executor.py b/python/ray/tune/tests/test_ray_trial_executor.py
index db0e945df69d4..abdb49a9a893c 100644
--- a/python/ray/tune/tests/test_ray_trial_executor.py
+++ b/python/ray/tune/tests/test_ray_trial_executor.py
@@ -4,11 +4,9 @@
 from __future__ import print_function
 
 import json
-import sys
 import unittest
 
 import ray
-from ray.exceptions import RayTimeoutError
 from ray.rllib import _register_all
 from ray.tune import Trainable
 from ray.tune.ray_trial_executor import RayTrialExecutor
@@ -18,11 +16,6 @@
 from ray.tune.resources import Resources
 from ray.cluster_utils import Cluster
 
-if sys.version_info >= (3, 3):
-    from unittest.mock import patch
-else:
-    from mock import patch
-
 
 class RayTrialExecutorTest(unittest.TestCase):
     def setUp(self):
diff --git a/python/ray/tune/tests/test_sync.py b/python/ray/tune/tests/test_sync.py
index 64621dc3e1a3e..85c36470b48d3 100644
--- a/python/ray/tune/tests/test_sync.py
+++ b/python/ray/tune/tests/test_sync.py
@@ -13,6 +13,7 @@
 from ray.rllib import _register_all
 
 from ray import tune
+from ray.tune import TuneError
 from ray.tune.syncer import CommandBasedClient
 
 if sys.version_info >= (3, 3):
@@ -29,7 +30,7 @@ def tearDown(self):
         ray.shutdown()
         _register_all()  # re-register the evicted objects
 
-    @patch("ray.tune.syncer.S3_PREFIX", "test")
+    @patch("ray.tune.sync_client.S3_PREFIX", "test")
     def testNoUploadDir(self):
         """No Upload Dir is given."""
         with self.assertRaises(AssertionError):
@@ -44,7 +45,7 @@ def testNoUploadDir(self):
                     "sync_to_cloud": "echo {source} {target}"
                 }).trials
 
-    @patch("ray.tune.syncer.S3_PREFIX", "test")
+    @patch("ray.tune.sync_client.S3_PREFIX", "test")
     def testCloudProperString(self):
         with self.assertRaises(ValueError):
             [trial] = tune.run(
@@ -93,7 +94,8 @@ def testCloudProperString(self):
 
     def testClusterProperString(self):
         """Tests that invalid commands throw.."""
-        with self.assertRaises(ValueError):
+        with self.assertRaises(TuneError):
+            # This raises TuneError because logger is init in safe zone.
             [trial] = tune.run(
                 "__fake",
                 name="foo",
@@ -105,7 +107,8 @@ def testClusterProperString(self):
                     "sync_to_driver": "ls {target}"
                 }).trials
 
-        with self.assertRaises(ValueError):
+        with self.assertRaises(TuneError):
+            # This raises TuneError because logger is init in safe zone.
             [trial] = tune.run(
                 "__fake",
                 name="foo",
@@ -117,7 +120,7 @@ def testClusterProperString(self):
                     "sync_to_driver": "ls {source}"
                 }).trials
 
-        with patch.object(CommandBasedClient, "execute") as mock_fn:
+        with patch.object(CommandBasedClient, "_execute") as mock_fn:
             with patch("ray.services.get_node_ip_address") as mock_sync:
                 mock_sync.return_value = "0.0.0.0"
                 [trial] = tune.run(
@@ -195,7 +198,7 @@ def testNoSync(self):
         def sync_func(source, target):
             pass
 
-        with patch.object(CommandBasedClient, "execute") as mock_sync:
+        with patch.object(CommandBasedClient, "_execute") as mock_sync:
             [trial] = tune.run(
                 "__fake",
                 name="foo",
diff --git a/python/ray/tune/trainable.py b/python/ray/tune/trainable.py
index 80572a97689a9..4e3b4937cff40 100644
--- a/python/ray/tune/trainable.py
+++ b/python/ray/tune/trainable.py
@@ -373,9 +373,14 @@ def restore_from_object(self, obj):
         shutil.rmtree(tmpdir)
 
     def delete_checkpoint(self, checkpoint_path):
+        """Deletes local copy of checkpoint.
+
+        Args:
+            checkpoint_path (str): Path to checkpoint.
+        """
         checkpoint_dir = os.path.dirname(checkpoint_path)
         if os.path.exists(checkpoint_dir):
-            os.rmdir(checkpoint_dir)
+            shutil.rmtree(checkpoint_dir)
 
     def export_model(self, export_formats, export_dir=None):
         """Exports model based on export_formats.
diff --git a/python/ray/tune/trial.py b/python/ray/tune/trial.py
index ffad1f778126e..135371c6f6bcc 100644
--- a/python/ray/tune/trial.py
+++ b/python/ray/tune/trial.py
@@ -199,7 +199,7 @@ def __init__(self,
         # Restoration fields
         self.restoring_from = None
         self.num_failures = 0
-        self.num_failures_between_results = 0  # Name this something better...
+        self.num_failures_since_result = 0
 
         # AutoML fields
         self.results = None
@@ -293,7 +293,7 @@ def close_logger(self):
     def write_error_log(self, error_msg):
         if error_msg and self.logdir:
             self.num_failures += 1
-            self.num_failures_between_results += 1
+            self.num_failures_since_result += 1
             self.error_file = os.path.join(self.logdir, "error.txt")
             with open(self.error_file, "a+") as f:
                 f.write("Failure # {} (occurred at {})\n".format(
@@ -350,8 +350,6 @@ def on_checkpoint(self, checkpoint):
                 # after this to handle checkpoints taken mid-sync.
                 self.result_logger.wait()
                 # Force sync down and wait before tracking the new checkpoint.
-                # This prevents attempts to restore from partially synced
-                # checkpoints.
                 if self.result_logger.sync_down():
                     self.result_logger.wait()
                 else:
@@ -361,7 +359,7 @@ def on_checkpoint(self, checkpoint):
         self.checkpoint_manager.on_checkpoint(checkpoint)
 
     def on_begin_restore(self, checkpoint):
-        """Handles newly dispatched restore.
+        """Handles dispatched async restore.
 
         This can be called multiple times without subsequently calling
         `on_restore` since a restoration attempt can fail.
@@ -398,7 +396,7 @@ def update_last_result(self, result, terminate=False):
             print("  {}".format(pretty_print(result).replace("\n", "\n  ")))
             self.last_debug = time.time()
         self.set_location(Location(result.get("node_ip"), result.get("pid")))
-        self.num_failures_between_results = 0
+        self.num_failures_since_result = 0
         self.last_result = result
         self.last_update_time = time.time()
         self.result_logger.on_result(self.last_result)
diff --git a/python/ray/tune/trial_executor.py b/python/ray/tune/trial_executor.py
index 921b325e32670..95b420dccb2e9 100644
--- a/python/ray/tune/trial_executor.py
+++ b/python/ray/tune/trial_executor.py
@@ -144,9 +144,9 @@ def reset_trial(self, trial, new_config, new_experiment_tag):
         raise NotImplementedError
 
     def get_running_trials(self):
-        """Returns all active trials."""
+        """Returns all running trials."""
         raise NotImplementedError("Subclasses of TrialExecutor must provide "
-                                  "get_active_trials() method")
+                                  "get_running_trials() method")
 
     def on_step_begin(self, trial_runner):
         """A hook called before running one step of the trial event loop."""
diff --git a/python/ray/tune/trial_runner.py b/python/ray/tune/trial_runner.py
index 54d2d0df7c2f1..cbd522ee92dd8 100644
--- a/python/ray/tune/trial_runner.py
+++ b/python/ray/tune/trial_runner.py
@@ -416,20 +416,6 @@ def _process_events(self):
                 with warn_if_slow("process_trial"):
                     self._process_trial(trial)
 
-    # def _process_trial_checkpoint(self, trial):
-    #     """Processes a trial's persisted checkpoint."""
-    #     value = None
-    #     try:
-    #         value = self.trial_executor.fetch_result(trial)
-    #     except Exception:
-    #         error_msg = "Trial {}: Error processing checkpoint".format(trial)
-    #         error_msg += "{}.".format(value) if value else ""
-    #         logger.exception(error_msg)
-    #     else:
-    #         checkpoint = Checkpoint(Checkpoint.PERSISTENT, value, trial.last_result)
-    #         trial.on_checkpoint(checkpoint)
-    #         # notify trial_executor according to cached decision.
-
     def _process_trial(self, trial):
         """Processes a trial result."""
         try:
@@ -501,7 +487,6 @@ def _process_trial_restore(self, trial):
         except Exception:
             logger.exception("Trial %s: Error processing restore.", trial)
             self._process_trial_failure(trial, traceback.format_exc())
-            return
 
     def _process_trial_failure(self, trial, error_msg):
         """Handle trial failure.