code: public short getBlockReplication(BlockInfo block) {
      if (storage.isSourceBlock(block)) {
        return getReplication();
      } else {
        if (storage.getStorageType() == StorageType.RAID_STORAGE) {
          return ((INodeRaidStorage)storage).getCodec().parityReplication;
        } else {
          throw new IllegalStateException("parity block " + block +
              " belongs to a non-raid file");
        }
      }
    }
docs: may have different replication