private boolean initRawKVStore(final StoreEngineOptions opts) {
        final StorageType storageType = opts.getStorageType();
        switch (storageType) {
            case RocksDB:
                return initRocksDB(opts);
            case Memory:
                return initMemoryDB(opts);
            default:
                throw new UnsupportedOperationException("unsupported storage type: " + storageType);
        }
    }
Storage engine, there is only one instance in a node,
containing one or more {@link RegionEngine}.

@author jiachun.fjc
jraft-rheakv/rheakv-core/src/main/java/com/alipay/sofa/jraft/rhea/StoreEngine.java