Currently in trunk, we have the layout version:
And in branch-2, we have:
We plan to backport
HDFS-5704 and HDFS-5777 to branch-2, thus EDITLOG_ADD_BLOCK will also take -48 in branch-2. However, we cannot change ADD_DATANODE_AND_STORAGE_UUIDS to -50 in branch-2. Otherwise fsimages written by trunk and branch-2 have the same layout -50 but branch-2 cannot read the -50 fsimage if it is written by trunk.