Thanks very much for replying. I was hoping these forums might be a bit busier but I guess there aren't so many people using community edition these days. Anyway, I did get this working in the end, but I was very disappointed in the lack of clear documentation. From what I remember this is what I did: **BACKUP NAMENODE BEFORE TOUCHING ANYTHING** 1) Shutdown the cluster 2) Upgraded to 5.11 using Parcels in CM. Did *NOT* restart cluster 3) Started ZooKeepers only 4) Went to HDFS and choose "Upgrade HDFS Metadata". The new binaries must be in place, and the cluster must be down 5) Then try to finalize the upgrade. I am not sure this worked as expected. I think there was an issue with one BP 6) re-started cluster 7) When to NameNode page and selected "Finalize Metadata Upgrade" After a long time it all sorted itself out and is up and running on 5.11 What a painful process though.
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