diff --git a/CHANGELOG.md b/CHANGELOG.md
index 7deeeafad..e3671e5dc 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,6 +1,8 @@
 # tip
 
 
+* FEATURE: allow setting `-retentionPeriod` smaller than one month. I.e. `-retentionPeriod=3d`, `-retentionPeriod=2w`, etc. is supported now.
+  See https://github.com/VictoriaMetrics/VictoriaMetrics/issues/173
 * FEATURE: optimize more cases according to https://utcc.utoronto.ca/~cks/space/blog/sysadmin/PrometheusLabelNonOptimization . Now the following cases are optimized too:
   * `rollup_func(foo{filters}[d]) op bar` -> `rollup_func(foo{filters}[d]) op bar{filters}`
   * `transform_func(foo{filters}) op bar` -> `transform_func(foo{filters}) op bar{filters}`
diff --git a/app/vmstorage/main.go b/app/vmstorage/main.go
index aa3235e38..8c0209a77 100644
--- a/app/vmstorage/main.go
+++ b/app/vmstorage/main.go
@@ -13,6 +13,7 @@ import (
 	"github.com/VictoriaMetrics/VictoriaMetrics/lib/buildinfo"
 	"github.com/VictoriaMetrics/VictoriaMetrics/lib/cgroup"
 	"github.com/VictoriaMetrics/VictoriaMetrics/lib/envflag"
+	"github.com/VictoriaMetrics/VictoriaMetrics/lib/flagutil"
 	"github.com/VictoriaMetrics/VictoriaMetrics/lib/fs"
 	"github.com/VictoriaMetrics/VictoriaMetrics/lib/httpserver"
 	"github.com/VictoriaMetrics/VictoriaMetrics/lib/logger"
@@ -22,8 +23,8 @@ import (
 )
 
 var (
+	retentionPeriod   = flagutil.NewDuration("retentionPeriod", 1, "Data with timestamps outside the retentionPeriod is automatically deleted")
 	httpListenAddr    = flag.String("httpListenAddr", ":8482", "Address to listen for http connections")
-	retentionPeriod   = flag.Int("retentionPeriod", 1, "Retention period in months")
 	storageDataPath   = flag.String("storageDataPath", "vmstorage-data", "Path to storage data")
 	vminsertAddr      = flag.String("vminsertAddr", ":8400", "TCP address to accept connections from vminsert services")
 	vmselectAddr      = flag.String("vmselectAddr", ":8401", "TCP address to accept connections from vmselect services")
@@ -53,11 +54,11 @@ func main() {
 	storage.SetBigMergeWorkersCount(*bigMergeConcurrency)
 	storage.SetSmallMergeWorkersCount(*smallMergeConcurrency)
 
-	logger.Infof("opening storage at %q with retention period %d months", *storageDataPath, *retentionPeriod)
+	logger.Infof("opening storage at %q with -retentionPeriod=%s", *storageDataPath, retentionPeriod)
 	startTime := time.Now()
-	strg, err := storage.OpenStorage(*storageDataPath, *retentionPeriod)
+	strg, err := storage.OpenStorage(*storageDataPath, retentionPeriod.Msecs)
 	if err != nil {
-		logger.Fatalf("cannot open a storage at %s with retention period %d months: %s", *storageDataPath, *retentionPeriod, err)
+		logger.Fatalf("cannot open a storage at %s with -retentionPeriod=%s: %s", *storageDataPath, retentionPeriod, err)
 	}
 
 	var m storage.Metrics
diff --git a/docs/Quick-Start.md b/docs/Quick-Start.md
index 80f1218e8..05d52ebea 100644
--- a/docs/Quick-Start.md
+++ b/docs/Quick-Start.md
@@ -8,7 +8,7 @@
    and their default values. Default flag values should fit the majoirty of cases. The minimum required flags to configure are:
 
    * `-storageDataPath` - path to directory where VictoriaMetrics stores all the data.
-   * `-retentionPeriod` - data retention in months.
+   * `-retentionPeriod` - data retention.
 
    For instance:
 
diff --git a/docs/Single-server-VictoriaMetrics.md b/docs/Single-server-VictoriaMetrics.md
index 81b10537f..16b85aa26 100644
--- a/docs/Single-server-VictoriaMetrics.md
+++ b/docs/Single-server-VictoriaMetrics.md
@@ -164,7 +164,7 @@ or [docker image](https://hub.docker.com/r/victoriametrics/victoria-metrics/) wi
 The following command-line flags are used the most:
 
 * `-storageDataPath` - path to data directory. VictoriaMetrics stores all the data in this directory. Default path is `victoria-metrics-data` in the current working directory.
-* `-retentionPeriod` - retention period in months for stored data. Older data is automatically deleted. Default period is 1 month.
+* `-retentionPeriod` - retention for stored data. Older data is automatically deleted. Default retention is 1 month. See [these docs](#retention) for more details.
 
 Other flags have good enough default values, so set them only if you really need this. Pass `-help` to see all the available flags with description and default values.
 
@@ -1048,6 +1048,7 @@ The de-duplication reduces disk space usage if multiple identically configured P
 write data to the same VictoriaMetrics instance. Note that these Prometheus instances must have identical
 `external_labels` section in their configs, so they write data to the same time series.
 
+
 ### Retention
 
 Retention is configured with `-retentionPeriod` command-line flag. For instance, `-retentionPeriod=3` means
@@ -1059,6 +1060,10 @@ For example if `-retentionPeriod` is set to 1, data for January is deleted on Ma
 It is safe to extend `-retentionPeriod` on existing data. If `-retentionPeriod` is set to lower
 value than before then data outside the configured period will be eventually deleted.
 
+VictoriaMetrics supports retention smaller than 1 month. For example, `-retentionPeriod=5d` would set data retention for 5 days.
+Older data is eventually deleted during [background merge](https://medium.com/@valyala/how-victoriametrics-makes-instant-snapshots-for-multi-terabyte-time-series-data-e1f3fb0e0282).
+
+
 ### Multiple retentions
 
 Just start multiple VictoriaMetrics instances with distinct values for the following flags:
diff --git a/lib/flagutil/duration.go b/lib/flagutil/duration.go
new file mode 100644
index 000000000..8dd920f67
--- /dev/null
+++ b/lib/flagutil/duration.go
@@ -0,0 +1,69 @@
+package flagutil
+
+import (
+	"flag"
+	"fmt"
+	"strconv"
+	"strings"
+
+	"github.com/VictoriaMetrics/metricsql"
+)
+
+// NewDuration returns new `duration` flag with the given name, defaultValue and description.
+//
+// DefaultValue is in months.
+func NewDuration(name string, defaultValue float64, description string) *Duration {
+	description += "\nThe following optional suffixes are supported: h (hour), d (day), w (week), y (year). If suffix isn't set, then the duration is counted in months"
+	d := Duration{
+		Msecs:       int64(defaultValue * msecsPerMonth),
+		valueString: fmt.Sprintf("%g", defaultValue),
+	}
+	flag.Var(&d, name, description)
+	return &d
+}
+
+// Duration is a flag for holding duration.
+type Duration struct {
+	// Msecs contains parsed duration in milliseconds.
+	Msecs int64
+
+	valueString string
+}
+
+// String implements flag.Value interface
+func (d *Duration) String() string {
+	return d.valueString
+}
+
+// Set implements flag.Value interface
+func (d *Duration) Set(value string) error {
+	// An attempt to parse value in months.
+	months, err := strconv.ParseFloat(value, 64)
+	if err == nil {
+		if months > maxMonths {
+			return fmt.Errorf("duration months must be smaller than %d; got %g", maxMonths, months)
+		}
+		if months < 0 {
+			return fmt.Errorf("duration months cannot be negative; got %g", months)
+		}
+		d.Msecs = int64(months * msecsPerMonth)
+		d.valueString = value
+		return nil
+	}
+	// Parse duration.
+	value = strings.ToLower(value)
+	if strings.HasSuffix(value, "m") {
+		return fmt.Errorf("duration in months must be set without `m` suffix due to ambiguity with duration in minutes; got %s", value)
+	}
+	msecs, err := metricsql.PositiveDurationValue(value, 0)
+	if err != nil {
+		return err
+	}
+	d.Msecs = msecs
+	d.valueString = value
+	return nil
+}
+
+const maxMonths = 12 * 100
+
+const msecsPerMonth = 31 * 24 * 3600 * 1000
diff --git a/lib/flagutil/duration_test.go b/lib/flagutil/duration_test.go
new file mode 100644
index 000000000..cdb1b5945
--- /dev/null
+++ b/lib/flagutil/duration_test.go
@@ -0,0 +1,57 @@
+package flagutil
+
+import (
+	"strings"
+	"testing"
+)
+
+func TestDurationSetFailure(t *testing.T) {
+	f := func(value string) {
+		t.Helper()
+		var d Duration
+		if err := d.Set(value); err == nil {
+			t.Fatalf("expecting non-nil error in d.Set(%q)", value)
+		}
+	}
+	f("")
+	f("foobar")
+	f("5foobar")
+	f("ah")
+	f("134xd")
+	f("2.43sdfw")
+
+	// Too big value in months
+	f("12345")
+
+	// Negative duration
+	f("-1")
+	f("-34h")
+
+	// Duration in minutes is confused with duration in months
+	f("1m")
+}
+
+func TestDurationSetSuccess(t *testing.T) {
+	f := func(value string, expectedMsecs int64) {
+		t.Helper()
+		var d Duration
+		if err := d.Set(value); err != nil {
+			t.Fatalf("unexpected error in d.Set(%q): %s", value, err)
+		}
+		if d.Msecs != expectedMsecs {
+			t.Fatalf("unexpected result; got %d; want %d", d.Msecs, expectedMsecs)
+		}
+		valueString := d.String()
+		valueExpected := strings.ToLower(value)
+		if valueString != valueExpected {
+			t.Fatalf("unexpected valueString; got %q; want %q", valueString, valueExpected)
+		}
+	}
+	f("0", 0)
+	f("1", msecsPerMonth)
+	f("123.456", 123.456*msecsPerMonth)
+	f("1h", 3600*1000)
+	f("1.5d", 1.5*24*3600*1000)
+	f("2.3W", 2.3*7*24*3600*1000)
+	f("0.25y", 0.25*365*24*3600*1000)
+}
diff --git a/lib/storage/merge.go b/lib/storage/merge.go
index 6f3463f91..6a1845ce9 100644
--- a/lib/storage/merge.go
+++ b/lib/storage/merge.go
@@ -15,12 +15,12 @@ import (
 //
 // rowsMerged is atomically updated with the number of merged rows during the merge.
 func mergeBlockStreams(ph *partHeader, bsw *blockStreamWriter, bsrs []*blockStreamReader, stopCh <-chan struct{},
-	dmis *uint64set.Set, rowsMerged, rowsDeleted *uint64) error {
+	dmis *uint64set.Set, retentionDeadline int64, rowsMerged, rowsDeleted *uint64) error {
 	ph.Reset()
 
 	bsm := bsmPool.Get().(*blockStreamMerger)
 	bsm.Init(bsrs)
-	err := mergeBlockStreamsInternal(ph, bsw, bsm, stopCh, dmis, rowsMerged, rowsDeleted)
+	err := mergeBlockStreamsInternal(ph, bsw, bsm, stopCh, dmis, retentionDeadline, rowsMerged, rowsDeleted)
 	bsm.reset()
 	bsmPool.Put(bsm)
 	bsw.MustClose()
@@ -39,7 +39,7 @@ var bsmPool = &sync.Pool{
 var errForciblyStopped = fmt.Errorf("forcibly stopped")
 
 func mergeBlockStreamsInternal(ph *partHeader, bsw *blockStreamWriter, bsm *blockStreamMerger, stopCh <-chan struct{},
-	dmis *uint64set.Set, rowsMerged, rowsDeleted *uint64) error {
+	dmis *uint64set.Set, retentionDeadline int64, rowsMerged, rowsDeleted *uint64) error {
 	// Search for the first block to merge
 	var pendingBlock *Block
 	for bsm.NextBlock() {
@@ -53,6 +53,11 @@ func mergeBlockStreamsInternal(ph *partHeader, bsw *blockStreamWriter, bsm *bloc
 			*rowsDeleted += uint64(bsm.Block.bh.RowsCount)
 			continue
 		}
+		if bsm.Block.bh.MaxTimestamp < retentionDeadline {
+			// Skip blocks out of the given retention.
+			*rowsDeleted += uint64(bsm.Block.bh.RowsCount)
+			continue
+		}
 		pendingBlock = getBlock()
 		pendingBlock.CopyFrom(bsm.Block)
 		break
@@ -75,6 +80,11 @@ func mergeBlockStreamsInternal(ph *partHeader, bsw *blockStreamWriter, bsm *bloc
 			*rowsDeleted += uint64(bsm.Block.bh.RowsCount)
 			continue
 		}
+		if bsm.Block.bh.MaxTimestamp < retentionDeadline {
+			// skip blocks out of the given retention.
+			*rowsDeleted += uint64(bsm.Block.bh.RowsCount)
+			continue
+		}
 
 		// Verify whether pendingBlock may be merged with bsm.Block (the current block).
 		if pendingBlock.bh.TSID.MetricID != bsm.Block.bh.TSID.MetricID {
diff --git a/lib/storage/merge_test.go b/lib/storage/merge_test.go
index 215af357d..dd12ccaff 100644
--- a/lib/storage/merge_test.go
+++ b/lib/storage/merge_test.go
@@ -365,7 +365,7 @@ func TestMergeForciblyStop(t *testing.T) {
 	ch := make(chan struct{})
 	var rowsMerged, rowsDeleted uint64
 	close(ch)
-	if err := mergeBlockStreams(&mp.ph, &bsw, bsrs, ch, nil, &rowsMerged, &rowsDeleted); !errors.Is(err, errForciblyStopped) {
+	if err := mergeBlockStreams(&mp.ph, &bsw, bsrs, ch, nil, 0, &rowsMerged, &rowsDeleted); !errors.Is(err, errForciblyStopped) {
 		t.Fatalf("unexpected error in mergeBlockStreams: got %v; want %v", err, errForciblyStopped)
 	}
 	if rowsMerged != 0 {
@@ -385,7 +385,7 @@ func testMergeBlockStreams(t *testing.T, bsrs []*blockStreamReader, expectedBloc
 	bsw.InitFromInmemoryPart(&mp)
 
 	var rowsMerged, rowsDeleted uint64
-	if err := mergeBlockStreams(&mp.ph, &bsw, bsrs, nil, nil, &rowsMerged, &rowsDeleted); err != nil {
+	if err := mergeBlockStreams(&mp.ph, &bsw, bsrs, nil, nil, 0, &rowsMerged, &rowsDeleted); err != nil {
 		t.Fatalf("unexpected error in mergeBlockStreams: %s", err)
 	}
 
diff --git a/lib/storage/merge_timing_test.go b/lib/storage/merge_timing_test.go
index 73a03ea29..38d2f5ba6 100644
--- a/lib/storage/merge_timing_test.go
+++ b/lib/storage/merge_timing_test.go
@@ -41,7 +41,7 @@ func benchmarkMergeBlockStreams(b *testing.B, mps []*inmemoryPart, rowsPerLoop i
 			}
 			mpOut.Reset()
 			bsw.InitFromInmemoryPart(&mpOut)
-			if err := mergeBlockStreams(&mpOut.ph, &bsw, bsrs, nil, nil, &rowsMerged, &rowsDeleted); err != nil {
+			if err := mergeBlockStreams(&mpOut.ph, &bsw, bsrs, nil, nil, 0, &rowsMerged, &rowsDeleted); err != nil {
 				panic(fmt.Errorf("cannot merge block streams: %w", err))
 			}
 		}
diff --git a/lib/storage/partition.go b/lib/storage/partition.go
index f159c0b98..ad5aaee2e 100644
--- a/lib/storage/partition.go
+++ b/lib/storage/partition.go
@@ -134,6 +134,10 @@ type partition struct {
 	// The callack that returns deleted metric ids which must be skipped during merge.
 	getDeletedMetricIDs func() *uint64set.Set
 
+	// data retention in milliseconds.
+	// Used for deleting data outside the retention during background merge.
+	retentionMsecs int64
+
 	// Name is the name of the partition in the form YYYY_MM.
 	name string
 
@@ -206,7 +210,7 @@ func (pw *partWrapper) decRef() {
 
 // createPartition creates new partition for the given timestamp and the given paths
 // to small and big partitions.
-func createPartition(timestamp int64, smallPartitionsPath, bigPartitionsPath string, getDeletedMetricIDs func() *uint64set.Set) (*partition, error) {
+func createPartition(timestamp int64, smallPartitionsPath, bigPartitionsPath string, getDeletedMetricIDs func() *uint64set.Set, retentionMsecs int64) (*partition, error) {
 	name := timestampToPartitionName(timestamp)
 	smallPartsPath := filepath.Clean(smallPartitionsPath) + "/" + name
 	bigPartsPath := filepath.Clean(bigPartitionsPath) + "/" + name
@@ -219,7 +223,7 @@ func createPartition(timestamp int64, smallPartitionsPath, bigPartitionsPath str
 		return nil, fmt.Errorf("cannot create directories for big parts %q: %w", bigPartsPath, err)
 	}
 
-	pt := newPartition(name, smallPartsPath, bigPartsPath, getDeletedMetricIDs)
+	pt := newPartition(name, smallPartsPath, bigPartsPath, getDeletedMetricIDs, retentionMsecs)
 	pt.tr.fromPartitionTimestamp(timestamp)
 	pt.startMergeWorkers()
 	pt.startRawRowsFlusher()
@@ -241,7 +245,7 @@ func (pt *partition) Drop() {
 }
 
 // openPartition opens the existing partition from the given paths.
-func openPartition(smallPartsPath, bigPartsPath string, getDeletedMetricIDs func() *uint64set.Set) (*partition, error) {
+func openPartition(smallPartsPath, bigPartsPath string, getDeletedMetricIDs func() *uint64set.Set, retentionMsecs int64) (*partition, error) {
 	smallPartsPath = filepath.Clean(smallPartsPath)
 	bigPartsPath = filepath.Clean(bigPartsPath)
 
@@ -265,7 +269,7 @@ func openPartition(smallPartsPath, bigPartsPath string, getDeletedMetricIDs func
 		return nil, fmt.Errorf("cannot open big parts from %q: %w", bigPartsPath, err)
 	}
 
-	pt := newPartition(name, smallPartsPath, bigPartsPath, getDeletedMetricIDs)
+	pt := newPartition(name, smallPartsPath, bigPartsPath, getDeletedMetricIDs, retentionMsecs)
 	pt.smallParts = smallParts
 	pt.bigParts = bigParts
 	if err := pt.tr.fromPartitionName(name); err != nil {
@@ -278,13 +282,14 @@ func openPartition(smallPartsPath, bigPartsPath string, getDeletedMetricIDs func
 	return pt, nil
 }
 
-func newPartition(name, smallPartsPath, bigPartsPath string, getDeletedMetricIDs func() *uint64set.Set) *partition {
+func newPartition(name, smallPartsPath, bigPartsPath string, getDeletedMetricIDs func() *uint64set.Set, retentionMsecs int64) *partition {
 	p := &partition{
 		name:           name,
 		smallPartsPath: smallPartsPath,
 		bigPartsPath:   bigPartsPath,
 
 		getDeletedMetricIDs: getDeletedMetricIDs,
+		retentionMsecs:      retentionMsecs,
 
 		mergeIdx: uint64(time.Now().UnixNano()),
 		stopCh:   make(chan struct{}),
@@ -1129,7 +1134,8 @@ func (pt *partition) mergeParts(pws []*partWrapper, stopCh <-chan struct{}) erro
 		atomic.AddUint64(&pt.smallMergesCount, 1)
 		atomic.AddUint64(&pt.activeSmallMerges, 1)
 	}
-	err := mergeBlockStreams(&ph, bsw, bsrs, stopCh, dmis, rowsMerged, rowsDeleted)
+	retentionDeadline := timestampFromTime(startTime) - pt.retentionMsecs
+	err := mergeBlockStreams(&ph, bsw, bsrs, stopCh, dmis, retentionDeadline, rowsMerged, rowsDeleted)
 	if isBigPart {
 		atomic.AddUint64(&pt.activeBigMerges, ^uint64(0))
 	} else {
diff --git a/lib/storage/partition_search_test.go b/lib/storage/partition_search_test.go
index 9342a9cbc..42c90fe83 100644
--- a/lib/storage/partition_search_test.go
+++ b/lib/storage/partition_search_test.go
@@ -167,7 +167,8 @@ func testPartitionSearchEx(t *testing.T, ptt int64, tr TimeRange, partsCount, ma
 	})
 
 	// Create partition from rowss and test search on it.
-	pt, err := createPartition(ptt, "./small-table", "./big-table", nilGetDeletedMetricIDs)
+	retentionMsecs := timestampFromTime(time.Now()) - ptr.MinTimestamp + 3600*1000
+	pt, err := createPartition(ptt, "./small-table", "./big-table", nilGetDeletedMetricIDs, retentionMsecs)
 	if err != nil {
 		t.Fatalf("cannot create partition: %s", err)
 	}
@@ -191,7 +192,7 @@ func testPartitionSearchEx(t *testing.T, ptt int64, tr TimeRange, partsCount, ma
 	pt.MustClose()
 
 	// Open the created partition and test search on it.
-	pt, err = openPartition(smallPartsPath, bigPartsPath, nilGetDeletedMetricIDs)
+	pt, err = openPartition(smallPartsPath, bigPartsPath, nilGetDeletedMetricIDs, retentionMsecs)
 	if err != nil {
 		t.Fatalf("cannot open partition: %s", err)
 	}
diff --git a/lib/storage/storage.go b/lib/storage/storage.go
index 16bc2133b..95410313e 100644
--- a/lib/storage/storage.go
+++ b/lib/storage/storage.go
@@ -27,7 +27,10 @@ import (
 	"github.com/VictoriaMetrics/fastcache"
 )
 
-const maxRetentionMonths = 12 * 100
+const (
+	msecsPerMonth     = 31 * 24 * 3600 * 1000
+	maxRetentionMsecs = 100 * 12 * msecsPerMonth
+)
 
 // Storage represents TSDB storage.
 type Storage struct {
@@ -117,23 +120,20 @@ type accountProjectKey struct {
 	ProjectID uint32
 }
 
-// OpenStorage opens storage on the given path with the given number of retention months.
-func OpenStorage(path string, retentionMonths int) (*Storage, error) {
-	if retentionMonths > maxRetentionMonths {
-		return nil, fmt.Errorf("too big retentionMonths=%d; cannot exceed %d", retentionMonths, maxRetentionMonths)
-	}
-	if retentionMonths <= 0 {
-		retentionMonths = maxRetentionMonths
-	}
+// OpenStorage opens storage on the given path with the given retentionMsecs.
+func OpenStorage(path string, retentionMsecs int64) (*Storage, error) {
 	path, err := filepath.Abs(path)
 	if err != nil {
 		return nil, fmt.Errorf("cannot determine absolute path for %q: %w", path, err)
 	}
-
+	if retentionMsecs <= 0 {
+		retentionMsecs = maxRetentionMsecs
+	}
+	retentionMonths := (retentionMsecs + (msecsPerMonth - 1)) / msecsPerMonth
 	s := &Storage{
 		path:            path,
 		cachePath:       path + "/cache",
-		retentionMonths: retentionMonths,
+		retentionMonths: int(retentionMonths),
 
 		stop: make(chan struct{}),
 	}
@@ -188,7 +188,7 @@ func OpenStorage(path string, retentionMonths int) (*Storage, error) {
 
 	// Load data
 	tablePath := path + "/data"
-	tb, err := openTable(tablePath, retentionMonths, s.getDeletedMetricIDs)
+	tb, err := openTable(tablePath, s.getDeletedMetricIDs, retentionMsecs)
 	if err != nil {
 		s.idb().MustClose()
 		return nil, fmt.Errorf("cannot open table at %q: %w", tablePath, err)
diff --git a/lib/storage/storage_test.go b/lib/storage/storage_test.go
index 60caf19a6..73c744d70 100644
--- a/lib/storage/storage_test.go
+++ b/lib/storage/storage_test.go
@@ -389,8 +389,8 @@ func TestStorageOpenMultipleTimes(t *testing.T) {
 
 func TestStorageRandTimestamps(t *testing.T) {
 	path := "TestStorageRandTimestamps"
-	retentionMonths := 60
-	s, err := OpenStorage(path, retentionMonths)
+	retentionMsecs := int64(60 * msecsPerMonth)
+	s, err := OpenStorage(path, retentionMsecs)
 	if err != nil {
 		t.Fatalf("cannot open storage: %s", err)
 	}
@@ -400,7 +400,7 @@ func TestStorageRandTimestamps(t *testing.T) {
 				t.Fatal(err)
 			}
 			s.MustClose()
-			s, err = OpenStorage(path, retentionMonths)
+			s, err = OpenStorage(path, retentionMsecs)
 		}
 	})
 	t.Run("concurrent", func(t *testing.T) {
diff --git a/lib/storage/table.go b/lib/storage/table.go
index ed2780361..faea8c1a0 100644
--- a/lib/storage/table.go
+++ b/lib/storage/table.go
@@ -22,6 +22,7 @@ type table struct {
 	bigPartitionsPath   string
 
 	getDeletedMetricIDs func() *uint64set.Set
+	retentionMsecs      int64
 
 	ptws     []*partitionWrapper
 	ptwsLock sync.Mutex
@@ -30,8 +31,7 @@ type table struct {
 
 	stop chan struct{}
 
-	retentionMilliseconds int64
-	retentionWatcherWG    sync.WaitGroup
+	retentionWatcherWG sync.WaitGroup
 }
 
 // partitionWrapper provides refcounting mechanism for the partition.
@@ -77,12 +77,12 @@ func (ptw *partitionWrapper) scheduleToDrop() {
 	atomic.AddUint64(&ptw.mustDrop, 1)
 }
 
-// openTable opens a table on the given path with the given retentionMonths.
+// openTable opens a table on the given path with the given retentionMsecs.
 //
 // The table is created if it doesn't exist.
 //
-// Data older than the retentionMonths may be dropped at any time.
-func openTable(path string, retentionMonths int, getDeletedMetricIDs func() *uint64set.Set) (*table, error) {
+// Data older than the retentionMsecs may be dropped at any time.
+func openTable(path string, getDeletedMetricIDs func() *uint64set.Set, retentionMsecs int64) (*table, error) {
 	path = filepath.Clean(path)
 
 	// Create a directory for the table if it doesn't exist yet.
@@ -115,7 +115,7 @@ func openTable(path string, retentionMonths int, getDeletedMetricIDs func() *uin
 	}
 
 	// Open partitions.
-	pts, err := openPartitions(smallPartitionsPath, bigPartitionsPath, getDeletedMetricIDs)
+	pts, err := openPartitions(smallPartitionsPath, bigPartitionsPath, getDeletedMetricIDs, retentionMsecs)
 	if err != nil {
 		return nil, fmt.Errorf("cannot open partitions in the table %q: %w", path, err)
 	}
@@ -125,6 +125,7 @@ func openTable(path string, retentionMonths int, getDeletedMetricIDs func() *uin
 		smallPartitionsPath: smallPartitionsPath,
 		bigPartitionsPath:   bigPartitionsPath,
 		getDeletedMetricIDs: getDeletedMetricIDs,
+		retentionMsecs:      retentionMsecs,
 
 		flockF: flockF,
 
@@ -133,11 +134,6 @@ func openTable(path string, retentionMonths int, getDeletedMetricIDs func() *uin
 	for _, pt := range pts {
 		tb.addPartitionNolock(pt)
 	}
-	if retentionMonths <= 0 || retentionMonths > maxRetentionMonths {
-		retentionMonths = maxRetentionMonths
-	}
-	tb.retentionMilliseconds = int64(retentionMonths) * 31 * 24 * 3600 * 1e3
-
 	tb.startRetentionWatcher()
 	return tb, nil
 }
@@ -357,7 +353,7 @@ func (tb *table) AddRows(rows []rawRow) error {
 			continue
 		}
 
-		pt, err := createPartition(r.Timestamp, tb.smallPartitionsPath, tb.bigPartitionsPath, tb.getDeletedMetricIDs)
+		pt, err := createPartition(r.Timestamp, tb.smallPartitionsPath, tb.bigPartitionsPath, tb.getDeletedMetricIDs, tb.retentionMsecs)
 		if err != nil {
 			errors = append(errors, err)
 			continue
@@ -376,7 +372,7 @@ func (tb *table) AddRows(rows []rawRow) error {
 
 func (tb *table) getMinMaxTimestamps() (int64, int64) {
 	now := int64(fasttime.UnixTimestamp() * 1000)
-	minTimestamp := now - tb.retentionMilliseconds
+	minTimestamp := now - tb.retentionMsecs
 	maxTimestamp := now + 2*24*3600*1000 // allow max +2 days from now due to timezones shit :)
 	if minTimestamp < 0 {
 		// Negative timestamps aren't supported by the storage.
@@ -406,7 +402,7 @@ func (tb *table) retentionWatcher() {
 		case <-ticker.C:
 		}
 
-		minTimestamp := int64(fasttime.UnixTimestamp()*1000) - tb.retentionMilliseconds
+		minTimestamp := int64(fasttime.UnixTimestamp()*1000) - tb.retentionMsecs
 		var ptwsDrop []*partitionWrapper
 		tb.ptwsLock.Lock()
 		dst := tb.ptws[:0]
@@ -457,7 +453,7 @@ func (tb *table) PutPartitions(ptws []*partitionWrapper) {
 	}
 }
 
-func openPartitions(smallPartitionsPath, bigPartitionsPath string, getDeletedMetricIDs func() *uint64set.Set) ([]*partition, error) {
+func openPartitions(smallPartitionsPath, bigPartitionsPath string, getDeletedMetricIDs func() *uint64set.Set, retentionMsecs int64) ([]*partition, error) {
 	// Certain partition directories in either `big` or `small` dir may be missing
 	// after restoring from backup. So populate partition names from both dirs.
 	ptNames := make(map[string]bool)
@@ -471,7 +467,7 @@ func openPartitions(smallPartitionsPath, bigPartitionsPath string, getDeletedMet
 	for ptName := range ptNames {
 		smallPartsPath := smallPartitionsPath + "/" + ptName
 		bigPartsPath := bigPartitionsPath + "/" + ptName
-		pt, err := openPartition(smallPartsPath, bigPartsPath, getDeletedMetricIDs)
+		pt, err := openPartition(smallPartsPath, bigPartsPath, getDeletedMetricIDs, retentionMsecs)
 		if err != nil {
 			mustClosePartitions(pts)
 			return nil, fmt.Errorf("cannot open partition %q: %w", ptName, err)
diff --git a/lib/storage/table_search.go b/lib/storage/table_search.go
index 50b5ea35b..f81dc2136 100644
--- a/lib/storage/table_search.go
+++ b/lib/storage/table_search.go
@@ -66,7 +66,7 @@ func (ts *tableSearch) Init(tb *table, tsids []TSID, tr TimeRange) {
 	// Adjust tr.MinTimestamp, so it doesn't obtain data older
 	// than the tb retention.
 	now := int64(fasttime.UnixTimestamp() * 1000)
-	minTimestamp := now - tb.retentionMilliseconds
+	minTimestamp := now - tb.retentionMsecs
 	if tr.MinTimestamp < minTimestamp {
 		tr.MinTimestamp = minTimestamp
 	}
diff --git a/lib/storage/table_search_test.go b/lib/storage/table_search_test.go
index d2f81e813..cda14c8b8 100644
--- a/lib/storage/table_search_test.go
+++ b/lib/storage/table_search_test.go
@@ -181,7 +181,7 @@ func testTableSearchEx(t *testing.T, trData, trSearch TimeRange, partitionsCount
 	})
 
 	// Create a table from rowss and test search on it.
-	tb, err := openTable("./test-table", -1, nilGetDeletedMetricIDs)
+	tb, err := openTable("./test-table", nilGetDeletedMetricIDs, maxRetentionMsecs)
 	if err != nil {
 		t.Fatalf("cannot create table: %s", err)
 	}
@@ -202,7 +202,7 @@ func testTableSearchEx(t *testing.T, trData, trSearch TimeRange, partitionsCount
 	tb.MustClose()
 
 	// Open the created table and test search on it.
-	tb, err = openTable("./test-table", -1, nilGetDeletedMetricIDs)
+	tb, err = openTable("./test-table", nilGetDeletedMetricIDs, maxRetentionMsecs)
 	if err != nil {
 		t.Fatalf("cannot open table: %s", err)
 	}
diff --git a/lib/storage/table_search_timing_test.go b/lib/storage/table_search_timing_test.go
index 42b450681..c45c9b334 100644
--- a/lib/storage/table_search_timing_test.go
+++ b/lib/storage/table_search_timing_test.go
@@ -47,7 +47,7 @@ func openBenchTable(b *testing.B, startTimestamp int64, rowsPerInsert, rowsCount
 		createBenchTable(b, path, startTimestamp, rowsPerInsert, rowsCount, tsidsCount)
 		createdBenchTables[path] = true
 	}
-	tb, err := openTable(path, -1, nilGetDeletedMetricIDs)
+	tb, err := openTable(path, nilGetDeletedMetricIDs, maxRetentionMsecs)
 	if err != nil {
 		b.Fatalf("cnanot open table %q: %s", path, err)
 	}
@@ -70,7 +70,7 @@ var createdBenchTables = make(map[string]bool)
 func createBenchTable(b *testing.B, path string, startTimestamp int64, rowsPerInsert, rowsCount, tsidsCount int) {
 	b.Helper()
 
-	tb, err := openTable(path, -1, nilGetDeletedMetricIDs)
+	tb, err := openTable(path, nilGetDeletedMetricIDs, maxRetentionMsecs)
 	if err != nil {
 		b.Fatalf("cannot open table %q: %s", path, err)
 	}
diff --git a/lib/storage/table_test.go b/lib/storage/table_test.go
index daeef21ee..68a76dbc9 100644
--- a/lib/storage/table_test.go
+++ b/lib/storage/table_test.go
@@ -7,7 +7,7 @@ import (
 
 func TestTableOpenClose(t *testing.T) {
 	const path = "TestTableOpenClose"
-	const retentionMonths = 123
+	const retentionMsecs = 123 * msecsPerMonth
 
 	if err := os.RemoveAll(path); err != nil {
 		t.Fatalf("cannot remove %q: %s", path, err)
@@ -17,7 +17,7 @@ func TestTableOpenClose(t *testing.T) {
 	}()
 
 	// Create a new table
-	tb, err := openTable(path, retentionMonths, nilGetDeletedMetricIDs)
+	tb, err := openTable(path, nilGetDeletedMetricIDs, retentionMsecs)
 	if err != nil {
 		t.Fatalf("cannot create new table: %s", err)
 	}
@@ -27,7 +27,7 @@ func TestTableOpenClose(t *testing.T) {
 
 	// Re-open created table multiple times.
 	for i := 0; i < 10; i++ {
-		tb, err := openTable(path, retentionMonths, nilGetDeletedMetricIDs)
+		tb, err := openTable(path, nilGetDeletedMetricIDs, retentionMsecs)
 		if err != nil {
 			t.Fatalf("cannot open created table: %s", err)
 		}
@@ -37,20 +37,20 @@ func TestTableOpenClose(t *testing.T) {
 
 func TestTableOpenMultipleTimes(t *testing.T) {
 	const path = "TestTableOpenMultipleTimes"
-	const retentionMonths = 123
+	const retentionMsecs = 123 * msecsPerMonth
 
 	defer func() {
 		_ = os.RemoveAll(path)
 	}()
 
-	tb1, err := openTable(path, retentionMonths, nilGetDeletedMetricIDs)
+	tb1, err := openTable(path, nilGetDeletedMetricIDs, retentionMsecs)
 	if err != nil {
 		t.Fatalf("cannot open table the first time: %s", err)
 	}
 	defer tb1.MustClose()
 
 	for i := 0; i < 10; i++ {
-		tb2, err := openTable(path, retentionMonths, nilGetDeletedMetricIDs)
+		tb2, err := openTable(path, nilGetDeletedMetricIDs, retentionMsecs)
 		if err == nil {
 			tb2.MustClose()
 			t.Fatalf("expecting non-nil error when opening already opened table")
diff --git a/lib/storage/table_timing_test.go b/lib/storage/table_timing_test.go
index 2a20add41..ed1ca8bde 100644
--- a/lib/storage/table_timing_test.go
+++ b/lib/storage/table_timing_test.go
@@ -45,7 +45,7 @@ func benchmarkTableAddRows(b *testing.B, rowsPerInsert, tsidsCount int) {
 	b.SetBytes(int64(rowsCountExpected))
 	tablePath := "./benchmarkTableAddRows"
 	for i := 0; i < b.N; i++ {
-		tb, err := openTable(tablePath, -1, nilGetDeletedMetricIDs)
+		tb, err := openTable(tablePath, nilGetDeletedMetricIDs, maxRetentionMsecs)
 		if err != nil {
 			b.Fatalf("cannot open table %q: %s", tablePath, err)
 		}
@@ -93,7 +93,7 @@ func benchmarkTableAddRows(b *testing.B, rowsPerInsert, tsidsCount int) {
 		tb.MustClose()
 
 		// Open the table from files and verify the rows count on it
-		tb, err = openTable(tablePath, -1, nilGetDeletedMetricIDs)
+		tb, err = openTable(tablePath, nilGetDeletedMetricIDs, maxRetentionMsecs)
 		if err != nil {
 			b.Fatalf("cannot open table %q: %s", tablePath, err)
 		}