public function moveOldBackup()
    {
        Service::$log->msg('S3: moving old backups');
        // remove the 2-day file
        $destinationFile = rtrim($this->s3Config->RemotePath, '/') . '/backup-2days-old';
        if ($this->s3Instance->doesObjectExist($this->s3Config->Bucket, $destinationFile)) {
            $this->s3Instance->deleteObject($this->s3Config->Bucket, $destinationFile);
        }

        // copy current 1-day file to 2-day
        $sourceFile = rtrim($this->s3Config->RemotePath, '/') . '/backup-1day-old';
        $destinationFile = rtrim($this->s3Config->RemotePath, '/') . '/backup-2days-old';
        if ($this->s3Instance->doesObjectExist($this->s3Config->Bucket, $sourceFile)) {
            $this->s3Instance->copyObject($this->s3Config->Bucket, $sourceFile, $this->s3Config->Bucket,
                $destinationFile);
        }

        // remove the old 1-day file
        $destinationFileTemp = rtrim($this->s3Config->RemotePath, '/') . '/backup-1day-old';
        if ($this->s3Instance->doesObjectExist($this->s3Config->Bucket, $destinationFileTemp)) {
            $this->s3Instance->deleteObject($this->s3Config->Bucket, $destinationFileTemp);
        }

        Service::$log->msg('S3: moving old backups done');

        return $destinationFile;
    }