diff --git a/pkg/local_object_storage/writecache/cache.go b/pkg/local_object_storage/writecache/cache.go
index 341071dc6..b97fc5856 100644
--- a/pkg/local_object_storage/writecache/cache.go
+++ b/pkg/local_object_storage/writecache/cache.go
@@ -45,10 +45,7 @@ const (
 	defaultMaxCacheSize  = 1 << 30          // 1 GiB
 )
 
-var (
-	defaultBucket                    = []byte{0}
-	dummyCanceler context.CancelFunc = func() {}
-)
+var dummyCanceler context.CancelFunc = func() {}
 
 // New creates new writecache instance.
 func New(opts ...Option) Cache {
diff --git a/pkg/local_object_storage/writecache/flush.go b/pkg/local_object_storage/writecache/flush.go
index 10e4d68f0..83933375b 100644
--- a/pkg/local_object_storage/writecache/flush.go
+++ b/pkg/local_object_storage/writecache/flush.go
@@ -1,12 +1,8 @@
 package writecache
 
 import (
-	"bytes"
 	"context"
 	"errors"
-	"fmt"
-	"os"
-	"path/filepath"
 	"time"
 
 	"git.frostfs.info/TrueCloudLab/frostfs-node/internal/logs"
@@ -20,8 +16,6 @@ import (
 	"git.frostfs.info/TrueCloudLab/frostfs-observability/tracing"
 	"git.frostfs.info/TrueCloudLab/frostfs-sdk-go/client"
 	objectSDK "git.frostfs.info/TrueCloudLab/frostfs-sdk-go/object"
-	oid "git.frostfs.info/TrueCloudLab/frostfs-sdk-go/object/id"
-	"go.etcd.io/bbolt"
 	"go.opentelemetry.io/otel/attribute"
 	"go.opentelemetry.io/otel/trace"
 	"go.uber.org/zap"
@@ -239,83 +233,3 @@ func (c *cache) Flush(ctx context.Context, ignoreErrors, seal bool) error {
 func (c *cache) flush(ctx context.Context, ignoreErrors bool) error {
 	return c.flushFSTree(ctx, ignoreErrors)
 }
-
-type batchItem struct {
-	data    []byte
-	address string
-}
-
-func (c *cache) flushAndDropBBoltDB(ctx context.Context) error {
-	_, err := os.Stat(filepath.Join(c.path, dbName))
-	if err != nil && os.IsNotExist(err) {
-		return nil
-	}
-	if err != nil {
-		return fmt.Errorf("could not check write-cache database existence: %w", err)
-	}
-	db, err := OpenDB(c.path, true, os.OpenFile)
-	if err != nil {
-		return fmt.Errorf("could not open write-cache database: %w", err)
-	}
-	defer func() {
-		_ = db.Close()
-	}()
-
-	var last string
-	for {
-		batch, err := c.readNextDBBatch(db, last)
-		if err != nil {
-			return err
-		}
-		if len(batch) == 0 {
-			break
-		}
-		for _, item := range batch {
-			var obj objectSDK.Object
-			if err := obj.Unmarshal(item.data); err != nil {
-				return fmt.Errorf("unmarshal object from database: %w", err)
-			}
-			if err := c.flushObject(ctx, &obj, item.data, StorageTypeDB); err != nil {
-				return fmt.Errorf("flush object from database: %w", err)
-			}
-		}
-		last = batch[len(batch)-1].address
-	}
-	if err := db.Close(); err != nil {
-		return fmt.Errorf("close write-cache database: %w", err)
-	}
-	if err := os.Remove(filepath.Join(c.path, dbName)); err != nil {
-		return fmt.Errorf("remove write-cache database: %w", err)
-	}
-	return nil
-}
-
-func (c *cache) readNextDBBatch(db *bbolt.DB, last string) ([]batchItem, error) {
-	const batchSize = 100
-	var batch []batchItem
-	err := db.View(func(tx *bbolt.Tx) error {
-		var addr oid.Address
-
-		b := tx.Bucket(defaultBucket)
-		cs := b.Cursor()
-		for k, data := cs.Seek([]byte(last)); k != nil; k, data = cs.Next() {
-			sa := string(k)
-			if sa == last {
-				continue
-			}
-			if err := addr.DecodeString(sa); err != nil {
-				return fmt.Errorf("decode address from database: %w", err)
-			}
-
-			batch = append(batch, batchItem{data: bytes.Clone(data), address: sa})
-			if len(batch) == batchSize {
-				return errIterationCompleted
-			}
-		}
-		return nil
-	})
-	if err == nil || errors.Is(err, errIterationCompleted) {
-		return batch, nil
-	}
-	return nil, err
-}
diff --git a/pkg/local_object_storage/writecache/storage.go b/pkg/local_object_storage/writecache/storage.go
index e708a529e..6aface7a5 100644
--- a/pkg/local_object_storage/writecache/storage.go
+++ b/pkg/local_object_storage/writecache/storage.go
@@ -16,8 +16,6 @@ import (
 	"go.uber.org/zap"
 )
 
-const dbName = "small.bolt"
-
 func (c *cache) openStore(mod mode.ComponentMode) error {
 	err := util.MkdirAllX(c.path, os.ModePerm)
 	if err != nil {
diff --git a/pkg/local_object_storage/writecache/upgrade.go b/pkg/local_object_storage/writecache/upgrade.go
new file mode 100644
index 000000000..3a100f1a3
--- /dev/null
+++ b/pkg/local_object_storage/writecache/upgrade.go
@@ -0,0 +1,110 @@
+package writecache
+
+import (
+	"bytes"
+	"context"
+	"errors"
+	"fmt"
+	"io/fs"
+	"os"
+	"path/filepath"
+	"time"
+
+	objectSDK "git.frostfs.info/TrueCloudLab/frostfs-sdk-go/object"
+	oid "git.frostfs.info/TrueCloudLab/frostfs-sdk-go/object/id"
+	"go.etcd.io/bbolt"
+)
+
+const dbName = "small.bolt"
+
+var defaultBucket = []byte{0}
+
+func (c *cache) flushAndDropBBoltDB(ctx context.Context) error {
+	_, err := os.Stat(filepath.Join(c.path, dbName))
+	if err != nil && os.IsNotExist(err) {
+		return nil
+	}
+	if err != nil {
+		return fmt.Errorf("could not check write-cache database existence: %w", err)
+	}
+	db, err := OpenDB(c.path, true, os.OpenFile)
+	if err != nil {
+		return fmt.Errorf("could not open write-cache database: %w", err)
+	}
+	defer func() {
+		_ = db.Close()
+	}()
+
+	var last string
+	for {
+		batch, err := c.readNextDBBatch(db, last)
+		if err != nil {
+			return err
+		}
+		if len(batch) == 0 {
+			break
+		}
+		for _, item := range batch {
+			var obj objectSDK.Object
+			if err := obj.Unmarshal(item.data); err != nil {
+				return fmt.Errorf("unmarshal object from database: %w", err)
+			}
+			if err := c.flushObject(ctx, &obj, item.data, StorageTypeDB); err != nil {
+				return fmt.Errorf("flush object from database: %w", err)
+			}
+		}
+		last = batch[len(batch)-1].address
+	}
+	if err := db.Close(); err != nil {
+		return fmt.Errorf("close write-cache database: %w", err)
+	}
+	if err := os.Remove(filepath.Join(c.path, dbName)); err != nil {
+		return fmt.Errorf("remove write-cache database: %w", err)
+	}
+	return nil
+}
+
+type batchItem struct {
+	data    []byte
+	address string
+}
+
+func (c *cache) readNextDBBatch(db *bbolt.DB, last string) ([]batchItem, error) {
+	const batchSize = 100
+	var batch []batchItem
+	err := db.View(func(tx *bbolt.Tx) error {
+		var addr oid.Address
+
+		b := tx.Bucket(defaultBucket)
+		cs := b.Cursor()
+		for k, data := cs.Seek([]byte(last)); k != nil; k, data = cs.Next() {
+			sa := string(k)
+			if sa == last {
+				continue
+			}
+			if err := addr.DecodeString(sa); err != nil {
+				return fmt.Errorf("decode address from database: %w", err)
+			}
+
+			batch = append(batch, batchItem{data: bytes.Clone(data), address: sa})
+			if len(batch) == batchSize {
+				return errIterationCompleted
+			}
+		}
+		return nil
+	})
+	if err == nil || errors.Is(err, errIterationCompleted) {
+		return batch, nil
+	}
+	return nil, err
+}
+
+// OpenDB opens BoltDB instance for write-cache. Opens in read-only mode if ro is true.
+func OpenDB(p string, ro bool, openFile func(string, int, fs.FileMode) (*os.File, error)) (*bbolt.DB, error) {
+	return bbolt.Open(filepath.Join(p, dbName), os.ModePerm, &bbolt.Options{
+		NoFreelistSync: true,
+		ReadOnly:       ro,
+		Timeout:        100 * time.Millisecond,
+		OpenFile:       openFile,
+	})
+}
diff --git a/pkg/local_object_storage/writecache/util.go b/pkg/local_object_storage/writecache/util.go
deleted file mode 100644
index 0ed4a954e..000000000
--- a/pkg/local_object_storage/writecache/util.go
+++ /dev/null
@@ -1,20 +0,0 @@
-package writecache
-
-import (
-	"io/fs"
-	"os"
-	"path/filepath"
-	"time"
-
-	"go.etcd.io/bbolt"
-)
-
-// OpenDB opens BoltDB instance for write-cache. Opens in read-only mode if ro is true.
-func OpenDB(p string, ro bool, openFile func(string, int, fs.FileMode) (*os.File, error)) (*bbolt.DB, error) {
-	return bbolt.Open(filepath.Join(p, dbName), os.ModePerm, &bbolt.Options{
-		NoFreelistSync: true,
-		ReadOnly:       ro,
-		Timeout:        100 * time.Millisecond,
-		OpenFile:       openFile,
-	})
-}