diff --git a/app/vmstorage/main.go b/app/vmstorage/main.go
index 511207d553..29dc613917 100644
--- a/app/vmstorage/main.go
+++ b/app/vmstorage/main.go
@@ -44,8 +44,9 @@ func main() {
 	partsCount := tm.SmallPartsCount + tm.BigPartsCount
 	blocksCount := tm.SmallBlocksCount + tm.BigBlocksCount
 	rowsCount := tm.SmallRowsCount + tm.BigRowsCount
-	logger.Infof("successfully opened storage %q in %s; partsCount: %d; blocksCount: %d; rowsCount: %d",
-		*storageDataPath, time.Since(startTime), partsCount, blocksCount, rowsCount)
+	sizeBytes := tm.SmallSizeBytes + tm.BigSizeBytes
+	logger.Infof("successfully opened storage %q in %s; partsCount: %d; blocksCount: %d; rowsCount: %d; sizeBytes: %d",
+		*storageDataPath, time.Since(startTime), partsCount, blocksCount, rowsCount, sizeBytes)
 
 	registerStorageMetrics(strg)
 
@@ -290,6 +291,16 @@ func registerStorageMetrics(strg *storage.Storage) {
 		return float64(idbm().BlocksCount)
 	})
 
+	metrics.NewGauge(`vm_data_size_bytes{type="storage/big"}`, func() float64 {
+		return float64(tm().BigSizeBytes)
+	})
+	metrics.NewGauge(`vm_data_size_bytes{type="storage/small"}`, func() float64 {
+		return float64(tm().SmallSizeBytes)
+	})
+	metrics.NewGauge(`vm_data_size_bytes{type="indexdb"}`, func() float64 {
+		return float64(idbm().SizeBytes)
+	})
+
 	metrics.NewGauge(`vm_rows{type="storage/big"}`, func() float64 {
 		return float64(tm().BigRowsCount)
 	})
diff --git a/lib/fs/fs.go b/lib/fs/fs.go
index 8c8501ba88..0a124a361d 100644
--- a/lib/fs/fs.go
+++ b/lib/fs/fs.go
@@ -185,6 +185,18 @@ func MustClose(f *os.File) {
 	}
 }
 
+// MustFileSize returns file size for the given path.
+func MustFileSize(path string) uint64 {
+	fi, err := os.Stat(path)
+	if err != nil {
+		logger.Panicf("FATAL: cannot stat %q: %s", path, err)
+	}
+	if fi.IsDir() {
+		logger.Panicf("FATAL: %q must be a file, not a directory", path)
+	}
+	return uint64(fi.Size())
+}
+
 // IsPathExist returns whether the given path exists.
 func IsPathExist(path string) bool {
 	if _, err := os.Stat(path); err != nil {
diff --git a/lib/mergeset/inmemory_part.go b/lib/mergeset/inmemory_part.go
index 897efa1c69..8297ec5f14 100644
--- a/lib/mergeset/inmemory_part.go
+++ b/lib/mergeset/inmemory_part.go
@@ -84,13 +84,18 @@ func (ip *inmemoryPart) Init(ib *inmemoryBlock) {
 // It is unsafe re-using ip while the returned part is in use.
 func (ip *inmemoryPart) NewPart() *part {
 	ph := ip.ph
-	p, err := newPart(&ph, "", ip.metaindexData.NewReader(), &ip.indexData, &ip.itemsData, &ip.lensData)
+	size := ip.size()
+	p, err := newPart(&ph, "", size, ip.metaindexData.NewReader(), &ip.indexData, &ip.itemsData, &ip.lensData)
 	if err != nil {
 		logger.Panicf("BUG: cannot create a part from inmemoryPart: %s", err)
 	}
 	return p
 }
 
+func (ip *inmemoryPart) size() uint64 {
+	return uint64(len(ip.metaindexData.B) + len(ip.indexData.B) + len(ip.itemsData.B) + len(ip.lensData.B))
+}
+
 func getInmemoryPart() *inmemoryPart {
 	v := ipPool.Get()
 	if v == nil {
diff --git a/lib/mergeset/part.go b/lib/mergeset/part.go
index da0ba01c23..2257c6f4e2 100644
--- a/lib/mergeset/part.go
+++ b/lib/mergeset/part.go
@@ -48,6 +48,8 @@ type part struct {
 
 	path string
 
+	size uint64
+
 	mrs []metaindexRow
 
 	indexFile fs.ReadAtCloser
@@ -71,6 +73,7 @@ func openFilePart(path string) (*part, error) {
 	if err != nil {
 		return nil, fmt.Errorf("cannot open %q: %s", metaindexPath, err)
 	}
+	metaindexSize := fs.MustFileSize(metaindexPath)
 
 	indexPath := path + "/index.bin"
 	indexFile, err := fs.OpenReaderAt(indexPath)
@@ -78,6 +81,7 @@ func openFilePart(path string) (*part, error) {
 		metaindexFile.MustClose()
 		return nil, fmt.Errorf("cannot open %q: %s", indexPath, err)
 	}
+	indexSize := fs.MustFileSize(indexPath)
 
 	itemsPath := path + "/items.bin"
 	itemsFile, err := fs.OpenReaderAt(itemsPath)
@@ -86,6 +90,7 @@ func openFilePart(path string) (*part, error) {
 		indexFile.MustClose()
 		return nil, fmt.Errorf("cannot open %q: %s", itemsPath, err)
 	}
+	itemsSize := fs.MustFileSize(itemsPath)
 
 	lensPath := path + "/lens.bin"
 	lensFile, err := fs.OpenReaderAt(lensPath)
@@ -95,11 +100,13 @@ func openFilePart(path string) (*part, error) {
 		itemsFile.MustClose()
 		return nil, fmt.Errorf("cannot open %q: %s", lensPath, err)
 	}
+	lensSize := fs.MustFileSize(lensPath)
 
-	return newPart(&ph, path, metaindexFile, indexFile, itemsFile, lensFile)
+	size := metaindexSize + indexSize + itemsSize + lensSize
+	return newPart(&ph, path, size, metaindexFile, indexFile, itemsFile, lensFile)
 }
 
-func newPart(ph *partHeader, path string, metaindexReader filestream.ReadCloser, indexFile, itemsFile, lensFile fs.ReadAtCloser) (*part, error) {
+func newPart(ph *partHeader, path string, size uint64, metaindexReader filestream.ReadCloser, indexFile, itemsFile, lensFile fs.ReadAtCloser) (*part, error) {
 	var errors []error
 	mrs, err := unmarshalMetaindexRows(nil, metaindexReader)
 	if err != nil {
@@ -109,6 +116,7 @@ func newPart(ph *partHeader, path string, metaindexReader filestream.ReadCloser,
 
 	p := &part{
 		path: path,
+		size: size,
 		mrs:  mrs,
 
 		indexFile: indexFile,
diff --git a/lib/mergeset/part_search_test.go b/lib/mergeset/part_search_test.go
index de6ac0576a..3e35f54a44 100644
--- a/lib/mergeset/part_search_test.go
+++ b/lib/mergeset/part_search_test.go
@@ -156,7 +156,8 @@ func newTestPart(blocksCount, maxItemsPerBlock int) (*part, []string, error) {
 	if itemsMerged != uint64(len(items)) {
 		return nil, nil, fmt.Errorf("unexpected itemsMerged; got %d; want %d", itemsMerged, len(items))
 	}
-	p, err := newPart(&ip.ph, "partName", ip.metaindexData.NewReader(), &ip.indexData, &ip.itemsData, &ip.lensData)
+	size := ip.size()
+	p, err := newPart(&ip.ph, "partName", size, ip.metaindexData.NewReader(), &ip.indexData, &ip.itemsData, &ip.lensData)
 	if err != nil {
 		return nil, nil, fmt.Errorf("cannot create part: %s", err)
 	}
diff --git a/lib/mergeset/table.go b/lib/mergeset/table.go
index e73e08c16a..480bf9d590 100644
--- a/lib/mergeset/table.go
+++ b/lib/mergeset/table.go
@@ -161,8 +161,8 @@ func OpenTable(path string) (*Table, error) {
 
 	var m TableMetrics
 	tb.UpdateMetrics(&m)
-	logger.Infof("table %q has been opened in %s; partsCount: %d; blocksCount: %d, itemsCount: %d",
-		path, time.Since(startTime), m.PartsCount, m.BlocksCount, m.ItemsCount)
+	logger.Infof("table %q has been opened in %s; partsCount: %d; blocksCount: %d, itemsCount: %d; sizeBytes: %d",
+		path, time.Since(startTime), m.PartsCount, m.BlocksCount, m.ItemsCount, m.SizeBytes)
 
 	return tb, nil
 }
@@ -242,6 +242,7 @@ type TableMetrics struct {
 
 	BlocksCount uint64
 	ItemsCount  uint64
+	SizeBytes   uint64
 
 	DataBlocksCacheSize     uint64
 	DataBlocksCacheRequests uint64
@@ -274,6 +275,7 @@ func (tb *Table) UpdateMetrics(m *TableMetrics) {
 
 		m.BlocksCount += p.ph.blocksCount
 		m.ItemsCount += p.ph.itemsCount
+		m.SizeBytes += p.size
 
 		m.DataBlocksCacheSize += p.ibCache.Len()
 		m.DataBlocksCacheRequests += p.ibCache.Requests()
@@ -727,6 +729,7 @@ func (tb *Table) mergeParts(pws []*partWrapper, stopCh <-chan struct{}, isOuterP
 	if err != nil {
 		return fmt.Errorf("cannot open merged part %q: %s", dstPartPath, err)
 	}
+	newPSize := newP.size
 	newPW := &partWrapper{
 		p:        newP,
 		refCount: 1,
@@ -761,7 +764,7 @@ func (tb *Table) mergeParts(pws []*partWrapper, stopCh <-chan struct{}, isOuterP
 
 	d := time.Since(startTime)
 	if d > 10*time.Second {
-		logger.Infof("merged %d items in %s at %d items/sec to %q", outItemsCount, d, int(float64(outItemsCount)/d.Seconds()), dstPartPath)
+		logger.Infof("merged %d items in %s at %d items/sec to %q; bytesSize: %d", outItemsCount, d, int(float64(outItemsCount)/d.Seconds()), dstPartPath, newPSize)
 	}
 
 	return nil
diff --git a/lib/storage/inmemory_part.go b/lib/storage/inmemory_part.go
index 2fb27f56c4..da8d78e56c 100644
--- a/lib/storage/inmemory_part.go
+++ b/lib/storage/inmemory_part.go
@@ -51,7 +51,8 @@ func (mp *inmemoryPart) InitFromRows(rows []rawRow) {
 // It is unsafe re-using mp while the returned part is in use.
 func (mp *inmemoryPart) NewPart() (*part, error) {
 	ph := mp.ph
-	return newPart(&ph, "", mp.metaindexData.NewReader(), &mp.timestampsData, &mp.valuesData, &mp.indexData)
+	size := uint64(len(mp.timestampsData.B) + len(mp.valuesData.B) + len(mp.indexData.B) + len(mp.metaindexData.B))
+	return newPart(&ph, "", size, mp.metaindexData.NewReader(), &mp.timestampsData, &mp.valuesData, &mp.indexData)
 }
 
 func getInmemoryPart() *inmemoryPart {
diff --git a/lib/storage/part.go b/lib/storage/part.go
index 6378d3f0f1..9cf7ec7585 100644
--- a/lib/storage/part.go
+++ b/lib/storage/part.go
@@ -36,6 +36,9 @@ type part struct {
 	// Empty for in-memory part.
 	path string
 
+	// Total size in bytes of part data.
+	size uint64
+
 	timestampsFile fs.ReadAtCloser
 	valuesFile     fs.ReadAtCloser
 	indexFile      fs.ReadAtCloser
@@ -59,6 +62,7 @@ func openFilePart(path string) (*part, error) {
 	if err != nil {
 		return nil, fmt.Errorf("cannot open timestamps file: %s", err)
 	}
+	timestampsSize := fs.MustFileSize(timestampsPath)
 
 	valuesPath := path + "/values.bin"
 	valuesFile, err := fs.OpenReaderAt(valuesPath)
@@ -66,6 +70,7 @@ func openFilePart(path string) (*part, error) {
 		timestampsFile.MustClose()
 		return nil, fmt.Errorf("cannot open values file: %s", err)
 	}
+	valuesSize := fs.MustFileSize(valuesPath)
 
 	indexPath := path + "/index.bin"
 	indexFile, err := fs.OpenReaderAt(indexPath)
@@ -74,6 +79,7 @@ func openFilePart(path string) (*part, error) {
 		valuesFile.MustClose()
 		return nil, fmt.Errorf("cannot open index file: %s", err)
 	}
+	indexSize := fs.MustFileSize(indexPath)
 
 	metaindexPath := path + "/metaindex.bin"
 	metaindexFile, err := filestream.Open(metaindexPath, true)
@@ -83,15 +89,17 @@ func openFilePart(path string) (*part, error) {
 		indexFile.MustClose()
 		return nil, fmt.Errorf("cannot open metaindex file: %s", err)
 	}
+	metaindexSize := fs.MustFileSize(metaindexPath)
 
-	return newPart(&ph, path, metaindexFile, timestampsFile, valuesFile, indexFile)
+	size := timestampsSize + valuesSize + indexSize + metaindexSize
+	return newPart(&ph, path, size, metaindexFile, timestampsFile, valuesFile, indexFile)
 }
 
 // newPart returns new part initialized with the given arguments.
 //
 // The returned part calls MustClose on all the files passed to newPart
 // when calling part.MustClose.
-func newPart(ph *partHeader, path string, metaindexReader filestream.ReadCloser, timestampsFile, valuesFile, indexFile fs.ReadAtCloser) (*part, error) {
+func newPart(ph *partHeader, path string, size uint64, metaindexReader filestream.ReadCloser, timestampsFile, valuesFile, indexFile fs.ReadAtCloser) (*part, error) {
 	var errors []error
 	metaindex, err := unmarshalMetaindexRows(nil, metaindexReader)
 	if err != nil {
@@ -102,6 +110,7 @@ func newPart(ph *partHeader, path string, metaindexReader filestream.ReadCloser,
 	p := &part{
 		ph:             *ph,
 		path:           path,
+		size:           size,
 		timestampsFile: timestampsFile,
 		valuesFile:     valuesFile,
 		indexFile:      indexFile,
diff --git a/lib/storage/partition.go b/lib/storage/partition.go
index 0803f16a26..b0327fef9e 100644
--- a/lib/storage/partition.go
+++ b/lib/storage/partition.go
@@ -282,6 +282,9 @@ type partitionMetrics struct {
 	SmallIndexBlocksCacheRequests uint64
 	SmallIndexBlocksCacheMisses   uint64
 
+	BigSizeBytes   uint64
+	SmallSizeBytes uint64
+
 	BigRowsCount   uint64
 	SmallRowsCount uint64
 
@@ -326,6 +329,7 @@ func (pt *partition) UpdateMetrics(m *partitionMetrics) {
 		m.BigIndexBlocksCacheMisses += p.ibCache.Misses()
 		m.BigRowsCount += p.ph.RowsCount
 		m.BigBlocksCount += p.ph.BlocksCount
+		m.BigSizeBytes += p.size
 		m.BigPartsRefCount += atomic.LoadUint64(&pw.refCount)
 	}
 
@@ -337,6 +341,7 @@ func (pt *partition) UpdateMetrics(m *partitionMetrics) {
 		m.SmallIndexBlocksCacheMisses += p.ibCache.Misses()
 		m.SmallRowsCount += p.ph.RowsCount
 		m.SmallBlocksCount += p.ph.BlocksCount
+		m.SmallSizeBytes += p.size
 		m.SmallPartsRefCount += atomic.LoadUint64(&pw.refCount)
 	}
 
@@ -1013,12 +1018,14 @@ func (pt *partition) mergeParts(pws []*partWrapper, stopCh <-chan struct{}) erro
 	}
 
 	var newPW *partWrapper
+	var newPSize uint64
 	if len(dstPartPath) > 0 {
 		// Open the merged part if it is non-empty.
 		newP, err := openFilePart(dstPartPath)
 		if err != nil {
 			return fmt.Errorf("cannot open merged part %q: %s", dstPartPath, err)
 		}
+		newPSize = newP.size
 		newPW = &partWrapper{
 			p:        newP,
 			refCount: 1,
@@ -1057,7 +1064,7 @@ func (pt *partition) mergeParts(pws []*partWrapper, stopCh <-chan struct{}) erro
 
 	d := time.Since(startTime)
 	if d > 10*time.Second {
-		logger.Infof("merged %d rows in %s at %d rows/sec to %q", outRowsCount, d, int(float64(outRowsCount)/d.Seconds()), dstPartPath)
+		logger.Infof("merged %d rows in %s at %d rows/sec to %q; sizeBytes: %d", outRowsCount, d, int(float64(outRowsCount)/d.Seconds()), dstPartPath, newPSize)
 	}
 
 	return nil