diff --git a/piker/data/feed.py b/piker/data/feed.py
index b877ed65..9f56cfd5 100644
--- a/piker/data/feed.py
+++ b/piker/data/feed.py
@@ -223,10 +223,13 @@ def diff_history(
             s_diff < 0
             and abs(s_diff) < len(array)
         ):
+            # the + 1 is because ``last_tsdb_dt`` is pulled from
+            # the last row entry for the ``'time'`` field retreived
+            # from the tsdb.
+            to_push = array[abs(s_diff)+1:]
             log.info(
                 f'Pushing partial frame {to_push.size} to shm'
             )
-            to_push = array[abs(s_diff):]
 
     return to_push
 
@@ -238,6 +241,7 @@ async def start_backfill(
 
     last_tsdb_dt: Optional[datetime] = None,
     storage: Optional[Storage] = None,
+    write_tsdb: bool = False,
 
     task_status: TaskStatus[trio.CancelScope] = trio.TASK_STATUS_IGNORED,
 
@@ -285,7 +289,7 @@ async def start_backfill(
             # based on the sample step size load a certain amount
             # history
             if step_size_s == 1:
-                last_tsdb_dt = pendulum.now().subtract(days=6)
+                last_tsdb_dt = pendulum.now().subtract(days=2)
 
             elif step_size_s == 60:
                 last_tsdb_dt = pendulum.now().subtract(years=2)
@@ -368,7 +372,7 @@ async def start_backfill(
 
             except NoData:
                 log.warning(
-                    f'NO DATA for {frame_size_s}s frame @ {end_dt} ?!?'
+                    f'NO DATA for {frame_size_s}s frame @ {input_end_dt} ?!?'
                 )
                 return None  # discard signal
 
@@ -425,10 +429,9 @@ async def start_backfill(
                     # gen already terminated meaning we probably already
                     # exhausted it via frame requests.
                     log.info(
-                        f"Datetime index already exhausted, can't reset.."
+                        "Datetime index already exhausted, can't reset.."
                     )
 
-
             to_push = diff_history(
                 array,
                 start_dt,
@@ -557,7 +560,10 @@ async def start_backfill(
                     # frame-result order.
                     earliest_end_dt = start_dt
 
-                    if storage is not None:
+                    if (
+                        storage is not None
+                        and write_tsdb
+                    ):
                         log.info(
                             f'Writing {ln} frame to storage:\n'
                             f'{start_dt} -> {end_dt}'