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Tsz Wo (Nicholas), SZE commented on HDFS-5526: ---------------------------------------------- > But during upgrade only clusterId and layoutVersion are overwritten, ctime is > never modified. clusterId and layoutVersion are never going to change > dynamically. right? You are right but we also need to consider some error cases such as connecting a DN to a wrong cluster, moving the storage to another DN, rolling back to a wrong version, upgrading again without rollback, etc. We need to make sure all the error cases will fail. I think it is the hard part. > Datanode cannot roll back to previous layout version > ---------------------------------------------------- > > Key: HDFS-5526 > URL: https://issues.apache.org/jira/browse/HDFS-5526 > Project: Hadoop HDFS > Issue Type: Bug > Components: datanode > Reporter: Tsz Wo (Nicholas), SZE > Assignee: Kihwal Lee > Priority: Blocker > Attachments: HDFS-5526.patch > > > Current trunk layout version is -48. > Hadoop v2.2.0 layout version is -47. > If a cluster is upgraded from v2.2.0 (-47) to trunk (-48), the datanodes > cannot start with -rollback. It will fail with IncorrectVersionException. -- This message was sent by Atlassian JIRA (v6.1#6144)