What is the purpose of running a block report prior to HDP upgrade?

[#1]

The upgrade instructions call for running a block report to be used later in the process but the docs never mention it again. Why do we run a block report? I know I have no corrupt blocks.

[#2 · Accepted solution]

Hi @Geoff Holmes

The block report portion of the pre-upgrade steps is, as you've suspected, to help administrations identify/locate/handle corrupt blocks prior to ugprading and also to validate any namespace issues. For manual upgrades, there is a step in the docs to manually compare the before and after block reports to identify any issues. I'm not sure whether Ambari based upgrades do the same check behind the scenes. It is not a step I would skip though

https://docs.hortonworks.com/HDPDocuments/HDP2/HDP-2.6.1/bk_command-line-upgrade/content/verify-hdfs...

[#3]

Thanks. I hadn't seen the command line upgrade instructions. I agree it's a good idea. In our case, it took nearly 4 hours to get the block report, so I wanted to make sure there was some value in having it.