cmd/frostfs-lens/internal/meta/root.go

@@ -5,6 +5,7 @@ import (
 
 	common "git.frostfs.info/TrueCloudLab/frostfs-node/cmd/frostfs-lens/internal"
 	meta "git.frostfs.info/TrueCloudLab/frostfs-node/pkg/local_object_storage/metabase"
+	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/local_object_storage/shard/mode"
 	"github.com/spf13/cobra"
 	"go.etcd.io/bbolt"
 )
@@ -43,7 +44,7 @@ func openMeta(cmd *cobra.Command) *meta.DB {
 		}),
 		meta.WithEpochState(epochState{}),
 	)
-	common.ExitOnErr(cmd, common.Errf("could not open metabase: %w", db.Open(cmd.Context(), true)))
+	common.ExitOnErr(cmd, common.Errf("could not open metabase: %w", db.Open(cmd.Context(), mode.ReadOnly)))
 
 	return db
 }

pkg/local_object_storage/blobstor/blobstor_test.go

@@ -11,6 +11,7 @@ import (
 	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/local_object_storage/blobstor/common"
 	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/local_object_storage/blobstor/fstree"
 	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/local_object_storage/blobstor/teststore"
+	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/local_object_storage/shard/mode"
 	objectSDK "git.frostfs.info/TrueCloudLab/frostfs-sdk-go/object"
 	"github.com/stretchr/testify/require"
 )
@@ -51,7 +52,7 @@ func TestCompression(t *testing.T) {
 		bs := New(
 			WithCompressObjects(compress),
 			WithStorages(defaultStorages(dir, smallSizeLimit)))
-		require.NoError(t, bs.Open(context.Background(), false))
+		require.NoError(t, bs.Open(context.Background(), mode.ReadWrite))
 		require.NoError(t, bs.Init())
 		return bs
 	}
@@ -126,7 +127,7 @@ func TestBlobstor_needsCompression(t *testing.T) {
 					Storage: fstree.New(fstree.WithPath(dir)),
 				},
 			}))
-		require.NoError(t, bs.Open(context.Background(), false))
+		require.NoError(t, bs.Open(context.Background(), mode.ReadWrite))
 		require.NoError(t, bs.Init())
 		return bs
 	}
@@ -188,7 +189,7 @@ func TestConcurrentPut(t *testing.T) {
 
 	blobStor := New(
 		WithStorages(defaultStorages(dir, smallSizeLimit)))
-	require.NoError(t, blobStor.Open(context.Background(), false))
+	require.NoError(t, blobStor.Open(context.Background(), mode.ReadWrite))
 	require.NoError(t, blobStor.Init())
 
 	testGet := func(t *testing.T, b *BlobStor, obj *objectSDK.Object) {
@@ -268,7 +269,7 @@ func TestConcurrentDelete(t *testing.T) {
 
 	blobStor := New(
 		WithStorages(defaultStorages(dir, smallSizeLimit)))
-	require.NoError(t, blobStor.Open(context.Background(), false))
+	require.NoError(t, blobStor.Open(context.Background(), mode.ReadWrite))
 	require.NoError(t, blobStor.Init())
 
 	testPut := func(t *testing.T, b *BlobStor, obj *objectSDK.Object) {

pkg/local_object_storage/blobstor/control.go

@@ -6,13 +6,29 @@ import (
 	"fmt"
 
 	"git.frostfs.info/TrueCloudLab/frostfs-node/internal/logs"
+	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/local_object_storage/shard/mode"
 	"go.uber.org/zap"
 )
 
 // Open opens BlobStor.
-func (b *BlobStor) Open(ctx context.Context, readOnly bool) error {
+func (b *BlobStor) Open(ctx context.Context, mode mode.Mode) error {
 	b.log.Debug(logs.BlobstorOpening)
 
+	b.modeMtx.Lock()
+	defer b.modeMtx.Unlock()
+	b.mode = mode
+
+	err := b.openBlobStor(ctx, mode)
+	if err != nil {
+		return err
+	}
+	b.metrics.SetMode(mode.ReadOnly())
+
+	return nil
+}
+
+func (b *BlobStor) openBlobStor(ctx context.Context, mode mode.Mode) error {
+	readOnly := mode.ReadOnly()
 	for i := range b.storage {
 		select {
 		case <-ctx.Done():
@@ -24,7 +40,6 @@ func (b *BlobStor) Open(ctx context.Context, readOnly bool) error {
 			return err
 		}
 	}
-	b.metrics.SetMode(readOnly)
 	return nil
 }
 

pkg/local_object_storage/blobstor/exists_test.go

@@ -7,6 +7,7 @@ import (
 	objectCore "git.frostfs.info/TrueCloudLab/frostfs-node/pkg/core/object"
 	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/local_object_storage/blobstor/common"
 	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/local_object_storage/blobstor/teststore"
+	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/local_object_storage/shard/mode"
 	cidtest "git.frostfs.info/TrueCloudLab/frostfs-sdk-go/container/id/test"
 	objectSDK "git.frostfs.info/TrueCloudLab/frostfs-sdk-go/object"
 	oidtest "git.frostfs.info/TrueCloudLab/frostfs-sdk-go/object/id/test"
@@ -20,7 +21,7 @@ func TestExists(t *testing.T) {
 
 	b := New(WithStorages(storages))
 
-	require.NoError(t, b.Open(context.Background(), false))
+	require.NoError(t, b.Open(context.Background(), mode.ReadWrite))
 	require.NoError(t, b.Init())
 
 	objects := []*objectSDK.Object{

pkg/local_object_storage/blobstor/iterate_test.go

@@ -7,6 +7,7 @@ import (
 	"testing"
 
 	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/local_object_storage/blobstor/common"
+	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/local_object_storage/shard/mode"
 	oid "git.frostfs.info/TrueCloudLab/frostfs-sdk-go/object/id"
 	oidtest "git.frostfs.info/TrueCloudLab/frostfs-sdk-go/object/id/test"
 	"github.com/stretchr/testify/require"
@@ -26,7 +27,7 @@ func TestIterateObjects(t *testing.T) {
 	defer os.RemoveAll(p)
 
 	// open Blobstor
-	require.NoError(t, blobStor.Open(context.Background(), false))
+	require.NoError(t, blobStor.Open(context.Background(), mode.ReadWrite))
 
 	// initialize Blobstor
 	require.NoError(t, blobStor.Init())

pkg/local_object_storage/blobstor/mode.go

@@ -22,7 +22,7 @@ func (b *BlobStor) SetMode(m mode.Mode) error {
 
 	err := b.Close()
 	if err == nil {
-		if err = b.Open(context.TODO(), m.ReadOnly()); err == nil {
+		if err = b.openBlobStor(context.TODO(), m); err == nil {
 			err = b.Init()
 		}
 	}

pkg/local_object_storage/internal/storagetest/storage.go

@@ -10,7 +10,7 @@ import (
 
 // Component represents single storage component.
 type Component interface {
-	Open(context.Context, bool) error
+	Open(context.Context, mode.Mode) error
 	SetMode(mode.Mode) error
 	Init() error
 	Close() error
@@ -58,18 +58,18 @@ func TestCloseAfterOpen(t *testing.T, cons Constructor) {
 	t.Run("RW", func(t *testing.T) {
 		// Use-case: irrecoverable error on some components, close everything.
 		s := cons(t)
-		require.NoError(t, s.Open(context.Background(), false))
+		require.NoError(t, s.Open(context.Background(), mode.ReadWrite))
 		require.NoError(t, s.Close())
 	})
 	t.Run("RO", func(t *testing.T) {
 		// Use-case: irrecoverable error on some components, close everything.
 		// Open in read-only must be done after the db is here.
 		s := cons(t)
-		require.NoError(t, s.Open(context.Background(), false))
+		require.NoError(t, s.Open(context.Background(), mode.ReadWrite))
 		require.NoError(t, s.Init())
 		require.NoError(t, s.Close())
 
-		require.NoError(t, s.Open(context.Background(), true))
+		require.NoError(t, s.Open(context.Background(), mode.ReadOnly))
 		require.NoError(t, s.Close())
 	})
 }
@@ -78,7 +78,7 @@ func TestCloseAfterOpen(t *testing.T, cons Constructor) {
 func TestCloseTwice(t *testing.T, cons Constructor) {
 	// Use-case: move to maintenance mode twice, first time failed.
 	s := cons(t)
-	require.NoError(t, s.Open(context.Background(), false))
+	require.NoError(t, s.Open(context.Background(), mode.ReadWrite))
 	require.NoError(t, s.Init())
 	require.NoError(t, s.Close())
 	require.NoError(t, s.Close()) // already closed, no-op
@@ -90,12 +90,12 @@ func TestSetMode(t *testing.T, cons Constructor, m mode.Mode) {
 		// Use-case: metabase `Init` failed,
 		// call `SetMode` on all not-yet-initialized components.
 		s := cons(t)
-		require.NoError(t, s.Open(context.Background(), false))
+		require.NoError(t, s.Open(context.Background(), mode.ReadWrite))
 		require.NoError(t, s.SetMode(m))
 
 		t.Run("after open in RO", func(t *testing.T) {
 			require.NoError(t, s.Close())
-			require.NoError(t, s.Open(context.Background(), true))
+			require.NoError(t, s.Open(context.Background(), mode.ReadOnly))
 			require.NoError(t, s.SetMode(m))
 		})
 
@@ -104,7 +104,7 @@ func TestSetMode(t *testing.T, cons Constructor, m mode.Mode) {
 	t.Run("after init", func(t *testing.T) {
 		s := cons(t)
 		// Use-case: notmal node operation.
-		require.NoError(t, s.Open(context.Background(), false))
+		require.NoError(t, s.Open(context.Background(), mode.ReadWrite))
 		require.NoError(t, s.Init())
 		require.NoError(t, s.SetMode(m))
 		require.NoError(t, s.Close())
@@ -114,7 +114,7 @@ func TestSetMode(t *testing.T, cons Constructor, m mode.Mode) {
 func TestModeTransition(t *testing.T, cons Constructor, from, to mode.Mode) {
 	// Use-case: normal node operation.
 	s := cons(t)
-	require.NoError(t, s.Open(context.Background(), false))
+	require.NoError(t, s.Open(context.Background(), mode.ReadWrite))
 	require.NoError(t, s.Init())
 	require.NoError(t, s.SetMode(from))
 	require.NoError(t, s.SetMode(to))

pkg/local_object_storage/metabase/control.go

@@ -22,7 +22,18 @@ var ErrDegradedMode = logicerr.New("metabase is in a degraded mode")
 var ErrReadOnlyMode = logicerr.New("metabase is in a read-only mode")
 
 // Open boltDB instance for metabase.
-func (db *DB) Open(_ context.Context, readOnly bool) error {
+func (db *DB) Open(_ context.Context, mode mode.Mode) error {
+	db.modeMtx.Lock()
+	defer db.modeMtx.Unlock()
+	db.mode = mode
+
+	if mode.NoMetabase() {
+		return nil
+	}
+	return db.openDB(mode)
+}
+
+func (db *DB) openDB(mode mode.Mode) error {
 	err := util.MkdirAllX(filepath.Dir(db.info.Path), db.info.Permission)
 	if err != nil {
 		return fmt.Errorf("can't create dir %s for metabase: %w", db.info.Path, err)
@@ -34,7 +45,7 @@ func (db *DB) Open(_ context.Context, readOnly bool) error {
 		opts := *bbolt.DefaultOptions
 		db.boltOptions = &opts
 	}
-	db.boltOptions.ReadOnly = readOnly
+	db.boltOptions.ReadOnly = mode.ReadOnly()
 
 	return metaerr.Wrap(db.openBolt())
 }

pkg/local_object_storage/metabase/db_test.go

@@ -9,6 +9,7 @@ import (
 	objectV2 "git.frostfs.info/TrueCloudLab/frostfs-api-go/v2/object"
 	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/local_object_storage/internal/testutil"
 	meta "git.frostfs.info/TrueCloudLab/frostfs-node/pkg/local_object_storage/metabase"
+	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/local_object_storage/shard/mode"
 	cid "git.frostfs.info/TrueCloudLab/frostfs-sdk-go/container/id"
 	objectSDK "git.frostfs.info/TrueCloudLab/frostfs-sdk-go/object"
 	oid "git.frostfs.info/TrueCloudLab/frostfs-sdk-go/object/id"
@@ -49,7 +50,7 @@ func newDB(t testing.TB, opts ...meta.Option) *meta.DB {
 		}, opts...)...,
 	)
 
-	require.NoError(t, bdb.Open(context.Background(), false))
+	require.NoError(t, bdb.Open(context.Background(), mode.ReadWrite))
 	require.NoError(t, bdb.Init())
 
 	return bdb

pkg/local_object_storage/metabase/mode.go

@@ -1,7 +1,6 @@
 package meta
 
 import (
-	"context"
 	"fmt"
 
 	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/local_object_storage/shard/mode"
@@ -23,21 +22,16 @@ func (db *DB) SetMode(m mode.Mode) error {
 		}
 	}
 
-	var err error
+	if m.NoMetabase() {
-	switch {
-	case m.NoMetabase():
 		db.boltDB = nil
-	case m.ReadOnly():
+	} else {
-		err = db.Open(context.TODO(), true)
+		err := db.openDB(m)
-	default:
+		if err == nil && !m.ReadOnly() {
-		err = db.Open(context.TODO(), false)
+			err = db.Init()
-	}
+		}
-	if err == nil && !m.NoMetabase() && !m.ReadOnly() {
+		if err != nil {
-		err = db.Init()
+			return fmt.Errorf("can't set metabase mode (old=%s, new=%s): %w", db.mode, m, err)
-	}
+		}
-
-	if err != nil {
-		return fmt.Errorf("can't set metabase mode (old=%s, new=%s): %w", db.mode, m, err)
 	}
 
 	db.mode = m

pkg/local_object_storage/metabase/mode_test.go

@@ -0,0 +1,37 @@
+package meta
+
+import (
+	"context"
+	"path/filepath"
+	"testing"
+
+	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/local_object_storage/shard/mode"
+	"github.com/stretchr/testify/require"
+)
+
+type epochStateTest struct{}
+
+func (s epochStateTest) CurrentEpoch() uint64 {
+	return 0
+}
+
+func Test_Mode(t *testing.T) {
+	t.Parallel()
+	bdb := New([]Option{
+		WithPath(filepath.Join(t.TempDir(), "metabase")),
+		WithPermissions(0o600),
+		WithEpochState(epochStateTest{}),
+	}...)
+
+	require.NoError(t, bdb.Open(context.Background(), mode.DegradedReadOnly))
+	require.Nil(t, bdb.boltDB)
+	require.NoError(t, bdb.Init())
+	require.Nil(t, bdb.boltDB)
+	require.NoError(t, bdb.Close())
+
+	require.NoError(t, bdb.Open(context.Background(), mode.Degraded))
+	require.Nil(t, bdb.boltDB)
+	require.NoError(t, bdb.Init())
+	require.Nil(t, bdb.boltDB)
+	require.NoError(t, bdb.Close())
+}

pkg/local_object_storage/metabase/version_test.go

@@ -8,6 +8,7 @@ import (
 	"path/filepath"
 	"testing"
 
+	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/local_object_storage/shard/mode"
 	"github.com/stretchr/testify/require"
 	"go.etcd.io/bbolt"
 )
@@ -43,13 +44,13 @@ func TestVersion(t *testing.T) {
 	}
 	t.Run("simple", func(t *testing.T) {
 		db := newDB(t)
-		require.NoError(t, db.Open(context.Background(), false))
+		require.NoError(t, db.Open(context.Background(), mode.ReadWrite))
 		require.NoError(t, db.Init())
 		check(t, db)
 		require.NoError(t, db.Close())
 
 		t.Run("reopen", func(t *testing.T) {
-			require.NoError(t, db.Open(context.Background(), false))
+			require.NoError(t, db.Open(context.Background(), mode.ReadWrite))
 			require.NoError(t, db.Init())
 			check(t, db)
 			require.NoError(t, db.Close())
@@ -57,29 +58,29 @@ func TestVersion(t *testing.T) {
 	})
 	t.Run("old data", func(t *testing.T) {
 		db := newDB(t)
-		require.NoError(t, db.Open(context.Background(), false))
+		require.NoError(t, db.Open(context.Background(), mode.ReadWrite))
 		require.NoError(t, db.WriteShardID([]byte{1, 2, 3, 4}))
 		require.NoError(t, db.Close())
 
-		require.NoError(t, db.Open(context.Background(), false))
+		require.NoError(t, db.Open(context.Background(), mode.ReadWrite))
 		require.NoError(t, db.Init())
 		check(t, db)
 		require.NoError(t, db.Close())
 	})
 	t.Run("invalid version", func(t *testing.T) {
 		db := newDB(t)
-		require.NoError(t, db.Open(context.Background(), false))
+		require.NoError(t, db.Open(context.Background(), mode.ReadWrite))
 		require.NoError(t, db.boltDB.Update(func(tx *bbolt.Tx) error {
 			return updateVersion(tx, version+1)
 		}))
 		require.NoError(t, db.Close())
 
-		require.NoError(t, db.Open(context.Background(), false))
+		require.NoError(t, db.Open(context.Background(), mode.ReadWrite))
 		require.Error(t, db.Init())
 		require.NoError(t, db.Close())
 
 		t.Run("reset", func(t *testing.T) {
-			require.NoError(t, db.Open(context.Background(), false))
+			require.NoError(t, db.Open(context.Background(), mode.ReadWrite))
 			require.NoError(t, db.Reset())
 			check(t, db)
 			require.NoError(t, db.Close())

pkg/local_object_storage/pilorama/bench_test.go

@@ -8,6 +8,7 @@ import (
 	"sync/atomic"
 	"testing"
 
+	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/local_object_storage/shard/mode"
 	cidtest "git.frostfs.info/TrueCloudLab/frostfs-sdk-go/container/id/test"
 	"github.com/stretchr/testify/require"
 )
@@ -26,7 +27,7 @@ func BenchmarkCreate(b *testing.B) {
 	f := NewBoltForest(
 		WithPath(filepath.Join(tmpDir, "test.db")),
 		WithMaxBatchSize(runtime.GOMAXPROCS(0)))
-	require.NoError(b, f.Open(context.Background(), false))
+	require.NoError(b, f.Open(context.Background(), mode.ReadWrite))
 	require.NoError(b, f.Init())
 	defer func() { require.NoError(b, f.Close()) }()
 

pkg/local_object_storage/pilorama/boltdb.go

@@ -99,7 +99,7 @@ func (t *boltForest) SetMode(m mode.Mode) error {
 
 	err := t.Close()
 	if err == nil && !m.NoMetabase() {
-		if err = t.Open(context.TODO(), m.ReadOnly()); err == nil {
+		if err = t.openBolt(m); err == nil {
 			err = t.Init()
 		}
 	}
@@ -112,7 +112,18 @@ func (t *boltForest) SetMode(m mode.Mode) error {
 	return nil
 }
 
-func (t *boltForest) Open(_ context.Context, readOnly bool) error {
+func (t *boltForest) Open(_ context.Context, mode mode.Mode) error {
+	t.modeMtx.Lock()
+	defer t.modeMtx.Unlock()
+	t.mode = mode
+	if mode.NoMetabase() {
+		return nil
+	}
+	return t.openBolt(mode)
+}
+
+func (t *boltForest) openBolt(mode mode.Mode) error {
+	readOnly := mode.ReadOnly()
 	err := util.MkdirAllX(filepath.Dir(t.path), t.perm)
 	if err != nil {
 		return metaerr.Wrap(fmt.Errorf("can't create dir %s for the pilorama: %w", t.path, err))
@@ -131,11 +142,7 @@ func (t *boltForest) Open(_ context.Context, readOnly bool) error {
 
 	t.db.MaxBatchSize = t.maxBatchSize
 	t.db.MaxBatchDelay = t.maxBatchDelay
-	m := mode.ReadWrite
+	t.metrics.SetMode(mode)
-	if readOnly {
-		m = mode.ReadOnly
-	}
-	t.metrics.SetMode(m)
 	return nil
 }
 

pkg/local_object_storage/pilorama/forest.go

@@ -111,7 +111,7 @@ func (f *memoryForest) Init() error {
 	return nil
 }
 
-func (f *memoryForest) Open(context.Context, bool) error {
+func (f *memoryForest) Open(context.Context, mode.Mode) error {
 	return nil
 }
 

pkg/local_object_storage/pilorama/forest_test.go

@@ -11,6 +11,7 @@ import (
 	"testing"
 	"time"
 
+	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/local_object_storage/shard/mode"
 	cidSDK "git.frostfs.info/TrueCloudLab/frostfs-sdk-go/container/id"
 	cidtest "git.frostfs.info/TrueCloudLab/frostfs-sdk-go/container/id/test"
 	objectSDK "git.frostfs.info/TrueCloudLab/frostfs-sdk-go/object"
@@ -24,7 +25,7 @@ var providers = []struct {
 }{
 	{"inmemory", func(t testing.TB, _ ...Option) ForestStorage {
 		f := NewMemoryForest()
-		require.NoError(t, f.Open(context.Background(), false))
+		require.NoError(t, f.Open(context.Background(), mode.ReadWrite))
 		require.NoError(t, f.Init())
 		return f
 	}},
@@ -34,7 +35,7 @@ var providers = []struct {
 				WithPath(filepath.Join(t.TempDir(), "test.db")),
 				WithMaxBatchSize(1),
 			}, opts...)...)
-		require.NoError(t, f.Open(context.Background(), false))
+		require.NoError(t, f.Open(context.Background(), mode.ReadWrite))
 		require.NoError(t, f.Init())
 		return f
 	}},

pkg/local_object_storage/pilorama/interface.go

@@ -58,7 +58,7 @@ type ForestStorage interface {
 	// DumpInfo returns information about the pilorama.
 	DumpInfo() Info
 	Init() error
-	Open(context.Context, bool) error
+	Open(context.Context, mode.Mode) error
 	Close() error
 	SetMode(m mode.Mode) error
 	SetParentID(id string)

pkg/local_object_storage/pilorama/mode_test.go

@@ -0,0 +1,31 @@
+package pilorama
+
+import (
+	"context"
+	"path/filepath"
+	"testing"
+
+	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/local_object_storage/shard/mode"
+	"github.com/stretchr/testify/require"
+)
+
+func Test_Mode(t *testing.T) {
+	t.Parallel()
+	f := NewBoltForest(
+		[]Option{
+			WithPath(filepath.Join(t.TempDir(), "test.db")),
+			WithMaxBatchSize(1),
+		}...)
+
+	require.NoError(t, f.Open(context.Background(), mode.DegradedReadOnly))
+	require.Nil(t, f.(*boltForest).db)
+	require.NoError(t, f.Init())
+	require.Nil(t, f.(*boltForest).db)
+	require.NoError(t, f.Close())
+
+	require.NoError(t, f.Open(context.Background(), mode.Degraded))
+	require.Nil(t, f.(*boltForest).db)
+	require.NoError(t, f.Init())
+	require.Nil(t, f.(*boltForest).db)
+	require.NoError(t, f.Close())
+}

pkg/local_object_storage/shard/control.go

@@ -43,12 +43,17 @@ func (s *Shard) handleMetabaseFailure(stage string, err error) error {
 // Open opens all Shard's components.
 func (s *Shard) Open(ctx context.Context) error {
 	components := []interface {
-		Open(context.Context, bool) error
+		Open(context.Context, mode.Mode) error
 	}{
-		s.blobStor, s.metaBase,
+		s.blobStor,
+	}
+	m := s.GetMode()
+
+	if !m.NoMetabase() {
+		components = append(components, s.metaBase)
 	}
 
-	if s.hasWriteCache() {
+	if s.hasWriteCache() && !m.NoMetabase() {
 		components = append(components, s.writeCache)
 	}
 
@@ -57,12 +62,12 @@ func (s *Shard) Open(ctx context.Context) error {
 	}
 
 	for i, component := range components {
-		if err := component.Open(ctx, false); err != nil {
+		if err := component.Open(ctx, m); err != nil {
 			if component == s.metaBase {
 				// We must first open all other components to avoid
 				// opening non-existent DB in read-only mode.
 				for j := i + 1; j < len(components); j++ {
-					if err := components[j].Open(ctx, false); err != nil {
+					if err := components[j].Open(ctx, m); err != nil {
 						// Other components must be opened, fail.
 						return fmt.Errorf("could not open %T: %w", components[j], err)
 					}
@@ -97,8 +102,9 @@ func (s *Shard) Init(ctx context.Context) error {
 	}
 
 	var components []initializer
+	m := s.GetMode()
 
-	if !s.GetMode().NoMetabase() {
+	if !m.NoMetabase() {
 		var initMetabase initializer
 
 		if s.NeedRefillMetabase() {
@@ -114,7 +120,7 @@ func (s *Shard) Init(ctx context.Context) error {
 		components = []initializer{s.blobStor}
 	}
 
-	if s.hasWriteCache() {
+	if s.hasWriteCache() && !m.NoMetabase() {
 		components = append(components, s.writeCache)
 	}
 

pkg/local_object_storage/shard/id.go

@@ -31,12 +31,11 @@ func (s *Shard) ID() *ID {
 
 // UpdateID reads shard ID saved in the metabase and updates it if it is missing.
 func (s *Shard) UpdateID(ctx context.Context) (err error) {
-	var metabaseOpened bool
 	var idFromMetabase []byte
-	if err = s.metaBase.Open(ctx, false); err != nil {
+	metabaseOpened := !s.GetMode().NoMetabase()
+	if err = s.metaBase.Open(ctx, s.GetMode()); err != nil {
 		err = fmt.Errorf("failed to open metabase: %w", err)
-	} else {
+		metabaseOpened = false
-		metabaseOpened = true
 	}
 	if metabaseOpened {
 		defer func() {

pkg/local_object_storage/writecache/benchmark/writecache_test.go

@@ -8,6 +8,7 @@ import (
 	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/local_object_storage/blobstor/teststore"
 	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/local_object_storage/internal/testutil"
 	meta "git.frostfs.info/TrueCloudLab/frostfs-node/pkg/local_object_storage/metabase"
+	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/local_object_storage/shard/mode"
 	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/local_object_storage/writecache"
 	"github.com/stretchr/testify/require"
 )
@@ -75,7 +76,7 @@ func benchmarkPutPar(b *testing.B, cache writecache.Cache, size uint64) {
 }
 
 func benchmarkPutPrepare(b *testing.B, cache writecache.Cache) {
-	require.NoError(b, cache.Open(context.Background(), false), "opening")
+	require.NoError(b, cache.Open(context.Background(), mode.ReadWrite), "opening")
 	require.NoError(b, cache.Init(), "initializing")
 }
 

pkg/local_object_storage/writecache/cachebbolt.go

@@ -95,8 +95,14 @@ func (c *cache) DumpInfo() Info {
 }
 
 // Open opens and initializes database. Reads object counters from the ObjectCounters instance.
-func (c *cache) Open(_ context.Context, readOnly bool) error {
+func (c *cache) Open(_ context.Context, mode mode.Mode) error {
-	err := c.openStore(readOnly)
+	c.modeMtx.Lock()
+	defer c.modeMtx.Unlock()
+	c.mode = mode
+	if mode.NoMetabase() {
+		return nil
+	}
+	err := c.openStore(mode.ReadOnly())
 	if err != nil {
 		return metaerr.Wrap(err)
 	}

pkg/local_object_storage/writecache/flush_test.go

@@ -202,7 +202,7 @@ func newCache[Option any](
 	mb := meta.New(
 		meta.WithPath(filepath.Join(dir, "meta")),
 		meta.WithEpochState(dummyEpoch{}))
-	require.NoError(t, mb.Open(context.Background(), false))
+	require.NoError(t, mb.Open(context.Background(), mode.ReadWrite))
 	require.NoError(t, mb.Init())
 
 	bs := blobstor.New(blobstor.WithStorages([]blobstor.SubStorage{
@@ -213,11 +213,11 @@ func newCache[Option any](
 				fstree.WithDirNameLen(1)),
 		},
 	}))
-	require.NoError(t, bs.Open(context.Background(), false))
+	require.NoError(t, bs.Open(context.Background(), mode.ReadWrite))
 	require.NoError(t, bs.Init())
 
 	wc := createCacheFn(t, smallSize, mb, bs, opts...)
-	require.NoError(t, wc.Open(context.Background(), false))
+	require.NoError(t, wc.Open(context.Background(), mode.ReadWrite))
 	require.NoError(t, wc.Init())
 
 	// First set mode for metabase and blobstor to prevent background flushes.

pkg/local_object_storage/writecache/mode_test.go

@@ -0,0 +1,30 @@
+package writecache
+
+import (
+	"context"
+	"testing"
+
+	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/local_object_storage/shard/mode"
+	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/util/logger/test"
+	"github.com/stretchr/testify/require"
+)
+
+func TestMode(t *testing.T) {
+	t.Parallel()
+	wc := New(
+		WithLogger(test.NewLogger(t)),
+		WithFlushWorkersCount(2),
+		WithPath(t.TempDir()))
+
+	require.NoError(t, wc.Open(context.Background(), mode.DegradedReadOnly))
+	require.Nil(t, wc.(*cache).db)
+	require.NoError(t, wc.Init())
+	require.Nil(t, wc.(*cache).db)
+	require.NoError(t, wc.Close())
+
+	require.NoError(t, wc.Open(context.Background(), mode.Degraded))
+	require.Nil(t, wc.(*cache).db)
+	require.NoError(t, wc.Init())
+	require.Nil(t, wc.(*cache).db)
+	require.NoError(t, wc.Close())
+}

pkg/local_object_storage/writecache/writecache.go

@@ -39,7 +39,7 @@ type Cache interface {
 	Seal(context.Context, bool) error
 
 	Init() error
-	Open(ctx context.Context, readOnly bool) error
+	Open(ctx context.Context, mode mode.Mode) error
 	Close() error
 }