d, err := newWarmBackend(ctx, tier, true)
	if err != nil {
		return err
	}

	if !ignoreInUse {
		// Check if warmbackend is in use by other MinIO tenants
		inUse, err := d.InUse(ctx)
		if err != nil {
			return err
		}
		if inUse {
			return errTierBackendInUse
		}
	}

	config.Tiers[tierName] = tier
	config.drivercache[tierName] = d

	return nil
}

	Get(ctx context.Context, object string, rv remoteVersionID, opts WarmBackendGetOpts) (io.ReadCloser, error)
	Remove(ctx context.Context, object string, rv remoteVersionID) error
	InUse(ctx context.Context) (bool, error)
}

const probeObject = "probeobject"

// checkWarmBackend checks if tier config credentials have sufficient privileges
// to perform all operations defined in the WarmBackend interface.

	if rv != "" {
		ropts.VersionID = string(rv)
	}
	err := s3.client.RemoveObject(ctx, s3.Bucket, s3.getDest(object), ropts)
	return s3.ToObjectError(err, object)
}

func (s3 *warmBackendS3) InUse(ctx context.Context) (bool, error) {
	result, err := s3.core.ListObjectsV2(s3.Bucket, s3.Prefix, "", "", slashSeparator, 1)
	if err != nil {
		return false, s3.ToObjectError(err)
	}

	_, err := az.clnt.DeleteBlob(ctx, az.Bucket, az.getDest(object), &azblob.DeleteBlobOptions{})
	return azureToObjectError(err, az.Bucket, az.getDest(object))
}

func (az *warmBackendAzure) InUse(ctx context.Context) (bool, error) {
	maxResults := int32(1)
	pager := az.clnt.NewListBlobsFlatPager(az.Bucket, &azblob.ListBlobsFlatOptions{
		Prefix:     &az.Prefix,
		MaxResults: &maxResults,
	})

	err := gcs.client.Bucket(gcs.Bucket).Object(gcs.getDest(key)).Delete(ctx)
	return gcsToObjectError(err, gcs.Bucket, key)
}

func (gcs *warmBackendGCS) InUse(ctx context.Context) (bool, error) {
	it := gcs.client.Bucket(gcs.Bucket).Objects(ctx, &storage.Query{
		Delimiter: "/",
		Prefix:    gcs.Prefix,
		Versions:  false,
	})
	pager := iterator.NewPager(it, 1, "")

	AssertEqual(t, ok, true)
	AssertEqual(t, len(conn.Stmts), 2)
	for _, stmt := range conn.Stmts {
		if stmt == nil {
			t.Fatalf("stmt cannot bee nil")
		}
	}

	AssertEqual(t, sqlDB.Stats().InUse, 0)
}

func TestPreparedStmtInTransaction(t *testing.T) {
	user := User{Name: "jinzhu"}

	if err := DB.Transaction(func(tx *gorm.DB) error {
		tx.Session(&gorm.Session{PrepareStmt: true}).Create(&user)