[ https://issues.apache.org/jira/browse/HDFS-7646?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Colin Patrick McCabe resolved HDFS-7646. ---------------------------------------- Resolution: Not a Problem > HDFS truncate may remove data from the supposedly read-only previous/ > directory during an upgrade > ------------------------------------------------------------------------------------------------- > > Key: HDFS-7646 > URL: https://issues.apache.org/jira/browse/HDFS-7646 > Project: Hadoop HDFS > Issue Type: Bug > Reporter: Colin Patrick McCabe > Priority: Blocker > > During a DataNode layout version upgrade, HDFS creates hardlinks. These > hardlinks allow the same block to be accessible from both the current/ and > previous/ directories. Rollback is possible by deleting the current/ > directory and renaming previous/ to current/. > However, if the user truncates one of these hardlinked block files, it > effectively eliminates the ability to roll back to the previous data. > We probably need to disable truncation-in-place during a DataNode upgrade. -- This message was sent by Atlassian JIRA (v6.3.4#6332)