diff --git a/RELEASE_NOTES.rst b/RELEASE_NOTES.rst
index a97f43d5e..fdb45ed7a 100644
--- a/RELEASE_NOTES.rst
+++ b/RELEASE_NOTES.rst
@@ -32,9 +32,6 @@ Highlights:
 * Previously detected RTIO async errors are reported to the host after each kernel terminates and a
   warning is logged. The warning is additional to the one already printed in the core device log upon
   detection of the error.
-* HDF5 options can now be passed when creating datasets with ``set_dataset``. This allows
-  in particular to use transparent compression filters as follows:
-  ``set_dataset(name, value, hdf5_options={"compression": "gzip"})``.
 * Removed worker DB warning for writing a dataset that is also in the archive
 
 Breaking changes:
@@ -51,10 +48,6 @@ Breaking changes:
   calling `ADF5356.init()`.
 * DRTIO: Changed message alignment from 32-bits to 64-bits.
 * The deprecated ``set_dataset(..., save=...)`` is no longer supported.
-* The internal dataset representation was changed to support tracking HDF5 options like e.g.
-  a compression method. This requires changes to code reading the dataset persistence file
-  (``dataset_db.pyon``) and to custom applets.
-
 
 ARTIQ-6
 -------
@@ -129,7 +122,6 @@ Breaking changes:
 * Experiment classes with underscore-prefixed names are now ignored when ``artiq_client``
   determines which experiment to submit (consistent with ``artiq_run``).
 
-
 ARTIQ-5
 -------
 
diff --git a/artiq/applets/big_number.py b/artiq/applets/big_number.py
index a0714b734..62348c8cf 100755
--- a/artiq/applets/big_number.py
+++ b/artiq/applets/big_number.py
@@ -13,7 +13,7 @@ class NumberWidget(QtWidgets.QLCDNumber):
 
     def data_changed(self, data, mods):
         try:
-            n = float(data[self.dataset_name]["value"])
+            n = float(data[self.dataset_name][1])
         except (KeyError, ValueError, TypeError):
             n = "---"
         self.display(n)
diff --git a/artiq/applets/image.py b/artiq/applets/image.py
index 4bc6b5f86..b7d36c1a1 100755
--- a/artiq/applets/image.py
+++ b/artiq/applets/image.py
@@ -13,7 +13,7 @@ class Image(pyqtgraph.ImageView):
 
     def data_changed(self, data, mods):
         try:
-            img = data[self.args.img]["value"]
+            img = data[self.args.img][1]
         except KeyError:
             return
         self.setImage(img)
diff --git a/artiq/applets/plot_hist.py b/artiq/applets/plot_hist.py
index 298246a5c..b3493c836 100755
--- a/artiq/applets/plot_hist.py
+++ b/artiq/applets/plot_hist.py
@@ -17,11 +17,11 @@ class HistogramPlot(pyqtgraph.PlotWidget):
 
     def data_changed(self, data, mods, title):
         try:
-            y = data[self.args.y]["value"]
+            y = data[self.args.y][1]
             if self.args.x is None:
                 x = None
             else:
-                x = data[self.args.x]["value"]
+                x = data[self.args.x][1]
         except KeyError:
             return
         if x is None:
diff --git a/artiq/applets/plot_xy.py b/artiq/applets/plot_xy.py
index 32bf95b50..8eaf9786a 100755
--- a/artiq/applets/plot_xy.py
+++ b/artiq/applets/plot_xy.py
@@ -6,7 +6,6 @@ from PyQt5.QtCore import QTimer
 import pyqtgraph
 
 from artiq.applets.simple import TitleApplet
-from artiq.master.databases import make_dataset as empty_dataset
 
 
 class XYPlot(pyqtgraph.PlotWidget):
@@ -22,14 +21,14 @@ class XYPlot(pyqtgraph.PlotWidget):
 
     def data_changed(self, data, mods, title):
         try:
-            y = data[self.args.y]["value"]
+            y = data[self.args.y][1]
         except KeyError:
             return
-        x = data.get(self.args.x, empty_dataset())["value"]
+        x = data.get(self.args.x, (False, None))[1]
         if x is None:
             x = np.arange(len(y))
-        error = data.get(self.args.error, empty_dataset())["value"]
-        fit = data.get(self.args.fit, empty_dataset())["value"]
+        error = data.get(self.args.error, (False, None))[1]
+        fit = data.get(self.args.fit, (False, None))[1]
 
         if not len(y) or len(y) != len(x):
             self.mismatch['X values'] = True
diff --git a/artiq/applets/plot_xy_hist.py b/artiq/applets/plot_xy_hist.py
index 01eab5421..39bd49098 100755
--- a/artiq/applets/plot_xy_hist.py
+++ b/artiq/applets/plot_xy_hist.py
@@ -126,9 +126,9 @@ class XYHistPlot(QtWidgets.QSplitter):
 
     def data_changed(self, data, mods):
         try:
-            xs = data[self.args.xs]["value"]
-            histogram_bins = data[self.args.histogram_bins]["value"]
-            histograms_counts = data[self.args.histograms_counts]["value"]
+            xs = data[self.args.xs][1]
+            histogram_bins = data[self.args.histogram_bins][1]
+            histograms_counts = data[self.args.histograms_counts][1]
         except KeyError:
             return
         if len(xs) != histograms_counts.shape[0]:
diff --git a/artiq/applets/simple.py b/artiq/applets/simple.py
index db6f2334d..e5776310a 100644
--- a/artiq/applets/simple.py
+++ b/artiq/applets/simple.py
@@ -10,7 +10,6 @@ from sipyco.sync_struct import Subscriber, process_mod
 from sipyco import pyon
 from sipyco.pipe_ipc import AsyncioChildComm
 
-from artiq.master.databases import make_dataset as empty_dataset
 
 logger = logging.getLogger(__name__)
 
@@ -252,7 +251,7 @@ class TitleApplet(SimpleApplet):
 
     def emit_data_changed(self, data, mod_buffer):
         if self.args.title is not None:
-            title_values = {k.replace(".", "/"): data.get(k, empty_dataset())["value"]
+            title_values = {k.replace(".", "/"): data.get(k, (False, None))[1]
                             for k in self.dataset_title}
             try:
                 title = self.args.title.format(**title_values)
diff --git a/artiq/browser/datasets.py b/artiq/browser/datasets.py
index d3d8171ac..b66b18216 100644
--- a/artiq/browser/datasets.py
+++ b/artiq/browser/datasets.py
@@ -104,8 +104,8 @@ class DatasetsDock(QtWidgets.QDockWidget):
             idx = self.table_model_filter.mapToSource(idx[0])
             key = self.table_model.index_to_key(idx)
             if key is not None:
-                dataset = self.table_model.backing_store[key]
-                asyncio.ensure_future(self._upload_dataset(key, dataset["value"]))
+                persist, value = self.table_model.backing_store[key]
+                asyncio.ensure_future(self._upload_dataset(key, value))
 
     def save_state(self):
         return bytes(self.table.header().saveState())
diff --git a/artiq/dashboard/datasets.py b/artiq/dashboard/datasets.py
index 23fc995cb..10e51e906 100644
--- a/artiq/dashboard/datasets.py
+++ b/artiq/dashboard/datasets.py
@@ -146,16 +146,16 @@ class Creator(QtWidgets.QDialog):
 
 
 class Model(DictSyncTreeSepModel):
-    def __init__(self, init):
-        DictSyncTreeSepModel.__init__(
-            self, ".", ["Dataset", "Persistent", "Value"], init
-        )
+    def __init__(self,  init):
+        DictSyncTreeSepModel.__init__(self, ".",
+                                      ["Dataset", "Persistent", "Value"],
+                                      init)
 
     def convert(self, k, v, column):
         if column == 1:
-            return "Y" if v["persist"] else "N"
+            return "Y" if v[0] else "N"
         elif column == 2:
-            return short_format(v["value"])
+            return short_format(v[1])
         else:
             raise ValueError
 
@@ -223,8 +223,8 @@ class DatasetsDock(QtWidgets.QDockWidget):
             idx = self.table_model_filter.mapToSource(idx[0])
             key = self.table_model.index_to_key(idx)
             if key is not None:
-                dataset = self.table_model.backing_store[key]
-                t = type(dataset["value"])
+                persist, value = self.table_model.backing_store[key]
+                t = type(value)
                 if np.issubdtype(t, np.number):
                     dialog_cls = NumberEditor
                 elif np.issubdtype(t, np.bool_):
@@ -235,7 +235,7 @@ class DatasetsDock(QtWidgets.QDockWidget):
                     logger.error("Cannot edit dataset %s: "
                                  "type %s is not supported", key, t)
                     return
-                dialog_cls(self, self.dataset_ctl, key, dataset["value"]).open()
+                dialog_cls(self, self.dataset_ctl, key, value).open()
 
     def delete_clicked(self):
         idx = self.table.selectedIndexes()
diff --git a/artiq/language/environment.py b/artiq/language/environment.py
index 819391925..969664d15 100644
--- a/artiq/language/environment.py
+++ b/artiq/language/environment.py
@@ -330,8 +330,7 @@ class HasEnvironment:
 
     @rpc(flags={"async"})
     def set_dataset(self, key, value,
-                    broadcast=False, persist=False, archive=True,
-                    hdf5_options=None):
+                    broadcast=False, persist=False, archive=True):
         """Sets the contents and handling modes of a dataset.
 
         Datasets must be scalars (``bool``, ``int``, ``float`` or NumPy scalar)
@@ -343,16 +342,8 @@ class HasEnvironment:
             broadcast.
         :param archive: the data is saved into the local storage of the current
             run (archived as a HDF5 file).
-        :param hdf5_options: dict of keyword arguments to pass to
-            :meth:`h5py.Group.create_dataset`. For example, pass ``{"compression": "gzip"}``
-            to enable transparent zlib compression of this dataset in the HDF5 archive.
-            See the `h5py documentation <https://docs.h5py.org/en/stable/high/group.html#h5py.Group.create_dataset>`_
-            for a list of valid options.
         """
-        
-        self.__dataset_mgr.set(
-            key, value, broadcast, persist, archive, hdf5_options
-        )
+        self.__dataset_mgr.set(key, value, broadcast, persist, archive)
 
     @rpc(flags={"async"})
     def mutate_dataset(self, key, index, value):
diff --git a/artiq/master/databases.py b/artiq/master/databases.py
index 8ef71c6a2..14cfae4cd 100644
--- a/artiq/master/databases.py
+++ b/artiq/master/databases.py
@@ -35,15 +35,6 @@ class DeviceDB:
         return desc
 
 
-def make_dataset(*, persist=False, value=None, hdf5_options=None):
-    "PYON-serializable representation of a dataset in the DatasetDB"
-    return {
-        "persist": persist,
-        "value": value,
-        "hdf5_options": hdf5_options or {},
-    }
-
-
 class DatasetDB(TaskObject):
     def __init__(self, persist_file, autosave_period=30):
         self.persist_file = persist_file
@@ -53,23 +44,10 @@ class DatasetDB(TaskObject):
             file_data = pyon.load_file(self.persist_file)
         except FileNotFoundError:
             file_data = dict()
-        self.data = Notifier(
-            {
-                k: make_dataset(
-                    persist=True,
-                    value=v["value"],
-                    hdf5_options=v["hdf5_options"]
-                )
-                for k, v in file_data.items()
-            }
-        )
+        self.data = Notifier({k: (True, v) for k, v in file_data.items()})
 
     def save(self):
-        data = {
-            k: d
-            for k, d in self.data.raw_view.items()
-            if d["persist"]
-        }
+        data = {k: v[1] for k, v in self.data.raw_view.items() if v[0]}
         pyon.store_file(self.persist_file, data)
 
     async def _do(self):
@@ -81,23 +59,20 @@ class DatasetDB(TaskObject):
             self.save()
 
     def get(self, key):
-        return self.data.raw_view[key]
+        return self.data.raw_view[key][1]
 
     def update(self, mod):
         process_mod(self.data, mod)
 
     # convenience functions (update() can be used instead)
-    def set(self, key, value, persist=None, hdf5_options=None):
+    def set(self, key, value, persist=None):
         if persist is None:
             if key in self.data.raw_view:
-                persist = self.data.raw_view[key]["persist"]
+                persist = self.data.raw_view[key][0]
             else:
                 persist = False
-        self.data[key] = make_dataset(
-            persist=persist,
-            value=value,
-            hdf5_options=hdf5_options,
-        )
+        self.data[key] = (persist, value)
 
     def delete(self, key):
         del self.data[key]
+    #
diff --git a/artiq/master/worker_db.py b/artiq/master/worker_db.py
index c739731a0..172846145 100644
--- a/artiq/master/worker_db.py
+++ b/artiq/master/worker_db.py
@@ -8,12 +8,9 @@ from operator import setitem
 import importlib
 import logging
 
-import numpy as np
-
 from sipyco.sync_struct import Notifier
 from sipyco.pc_rpc import AutoTarget, Client, BestEffortClient
 
-from artiq.master.databases import make_dataset
 
 logger = logging.getLogger(__name__)
 
@@ -118,26 +115,22 @@ class DatasetManager:
         self.ddb = ddb
         self._broadcaster.publish = ddb.update
 
-    def set(self, key, value, broadcast=False, persist=False, archive=True,
-            hdf5_options=None):
+    def set(self, key, value, broadcast=False, persist=False, archive=True):
+        if key in self.archive:
+            logger.warning("Modifying dataset '%s' which is in archive, "
+                           "archive will remain untouched",
+                           key, stack_info=True)
+
         if persist:
             broadcast = True
 
         if broadcast:
-            self._broadcaster[key] = make_dataset(
-                persist=persist,
-                value=value,
-                hdf5_options=hdf5_options,
-            )
+            self._broadcaster[key] = persist, value
         elif key in self._broadcaster.raw_view:
             del self._broadcaster[key]
 
         if archive:
-            self.local[key] = make_dataset(
-                persist=persist,
-                value=value,
-                hdf5_options=hdf5_options,
-            )
+            self.local[key] = value
         elif key in self.local:
             del self.local[key]
 
@@ -145,11 +138,11 @@ class DatasetManager:
         target = self.local.get(key, None)
         if key in self._broadcaster.raw_view:
             if target is not None:
-                assert target["value"] is self._broadcaster.raw_view[key]["value"]
-            return self._broadcaster[key]["value"]
+                assert target is self._broadcaster.raw_view[key][1]
+            return self._broadcaster[key][1]
         if target is None:
             raise KeyError("Cannot mutate nonexistent dataset '{}'".format(key))
-        return target["value"]
+        return target
 
     def mutate(self, key, index, value):
         target = self._get_mutation_target(key)
@@ -165,15 +158,15 @@ class DatasetManager:
 
     def get(self, key, archive=False):
         if key in self.local:
-            return self.local[key]["value"]
-
-        dataset = self.ddb.get(key)
+            return self.local[key]
+        
+        data = self.ddb.get(key)
         if archive:
             if key in self.archive:
                 logger.warning("Dataset '%s' is already in archive, "
                                "overwriting", key, stack_info=True)
-            self.archive[key] = dataset
-        return dataset["value"]
+            self.archive[key] = data
+        return data
 
     def write_hdf5(self, f):
         datasets_group = f.create_group("datasets")
@@ -189,7 +182,7 @@ def _write(group, k, v):
     # Add context to exception message when the user writes a dataset that is
     # not representable in HDF5.
     try:
-        group.create_dataset(k, data=v["value"], **v["hdf5_options"])
+        group[k] = v
     except TypeError as e:
         raise TypeError("Error writing dataset '{}' of type '{}': {}".format(
-            k, type(v["value"]), e))
+            k, type(v), e))
diff --git a/artiq/test/test_datasets.py b/artiq/test/test_datasets.py
index 3fa6d6bb7..871568a2a 100644
--- a/artiq/test/test_datasets.py
+++ b/artiq/test/test_datasets.py
@@ -3,9 +3,6 @@
 import copy
 import unittest
 
-import h5py
-import numpy as np
-
 from sipyco.sync_struct import process_mod
 
 from artiq.experiment import EnvExperiment
@@ -17,7 +14,7 @@ class MockDatasetDB:
         self.data = dict()
 
     def get(self, key):
-        return self.data[key]["value"]
+        return self.data[key][1]
 
     def update(self, mod):
         # Copy mod before applying to avoid sharing references to objects
@@ -85,9 +82,9 @@ class ExperimentDatasetCase(unittest.TestCase):
     def test_append_broadcast(self):
         self.exp.set(KEY, [], broadcast=True)
         self.exp.append(KEY, 0)
-        self.assertEqual(self.dataset_db.data[KEY]["value"], [0])
+        self.assertEqual(self.dataset_db.data[KEY][1], [0])
         self.exp.append(KEY, 1)
-        self.assertEqual(self.dataset_db.data[KEY]["value"], [0, 1])
+        self.assertEqual(self.dataset_db.data[KEY][1], [0, 1])
 
     def test_append_array(self):
         for broadcast in (True, False):
@@ -106,44 +103,3 @@ class ExperimentDatasetCase(unittest.TestCase):
         with self.assertRaises(KeyError):
             self.exp.append(KEY, 0)
 
-    def test_write_hdf5_options(self):
-        data = np.random.randint(0, 1024, 1024)
-        self.exp.set(
-            KEY,
-            data,
-            hdf5_options=dict(
-                compression="gzip",
-                compression_opts=6,
-                shuffle=True,
-                fletcher32=True
-            ),
-        )
-
-        with h5py.File("test.h5", "a", "core", backing_store=False) as f:
-            self.dataset_mgr.write_hdf5(f)
-
-            self.assertTrue(np.array_equal(f["datasets"][KEY][()], data))
-            self.assertEqual(f["datasets"][KEY].compression, "gzip")
-            self.assertEqual(f["datasets"][KEY].compression_opts, 6)
-            self.assertTrue(f["datasets"][KEY].shuffle)
-            self.assertTrue(f["datasets"][KEY].fletcher32)
-
-    def test_write_hdf5_no_options(self):
-        data = np.random.randint(0, 1024, 1024)
-        self.exp.set(KEY, data)
-
-        with h5py.File("test.h5", "a", "core", backing_store=False) as f:
-            self.dataset_mgr.write_hdf5(f)
-            self.assertTrue(np.array_equal(f["datasets"][KEY][()], data))
-            self.assertIsNone(f["datasets"][KEY].compression)
-
-    def test_write_hdf5_invalid_type(self):
-        class CustomType:
-            def __init__(self, x):
-                self.x = x
-
-        self.exp.set(KEY, CustomType(42))
-
-        with h5py.File("test.h5", "w", "core", backing_store=False) as f:
-            with self.assertRaisesRegex(TypeError, "CustomType"):
-                self.dataset_mgr.write_hdf5(f)
diff --git a/artiq/test/test_scheduler.py b/artiq/test/test_scheduler.py
index 984804fcf..b4327e72e 100644
--- a/artiq/test/test_scheduler.py
+++ b/artiq/test/test_scheduler.py
@@ -6,7 +6,6 @@ from time import time, sleep
 
 from artiq.experiment import *
 from artiq.master.scheduler import Scheduler
-from artiq.master.databases import make_dataset
 
 
 class EmptyExperiment(EnvExperiment):
@@ -288,13 +287,8 @@ class SchedulerCase(unittest.TestCase):
             nonlocal termination_ok
             self.assertEqual(
                 mod,
-                {
-                    "action": "setitem",
-                    "key": "termination_ok",
-                    "value": make_dataset(value=True),
-                    "path": []
-                }
-            )
+                {"action": "setitem", "key": "termination_ok",
+                 "value": (False, True), "path": []})
             termination_ok = True
         handlers = {
             "update_dataset": check_termination