Add '-rollingUpgrade <rollback|downgrade>' to namenode usage message
Vinayakumar B, can you also take a look HDFS-5778, which is rolling upgrade document, I do think you'd better update HDFS-5578.
Attached simple patch
Hi Fengdong Yu, I checked HDFS-5778, its not including this change.
Thanks Vinay, could you put downgrade before rollback? Downgrade is much preferable if it can be run.
I have put downgrade before rollback in latest patch
+1 patch looks good.
I have committed this. Thanks, Vinay!