public byte getDatacenterId() {
    return datacenterId;
  }
Gets the id of the datacenter where this blob was originally posted. If this information was not available
when the blobId was formed, it will return {@link ClusterMap#UNKNOWN_DATACENTER_ID}.
@return The id of the datacenter where this blob was originally posted.
ambry-commons/src/main/java/com/github/ambry/commons/BlobId.java