[ http://issues.apache.org/jira/browse/HADOOP-702?page=comments#action_12448617 ] Yoram Arnon commented on HADOOP-702: ------------------------------------
there are two things you can do with a snapshot: view individual files or roll back the entire FS. We currently plan to support only the latter, more extreme option, typically used only in case of disasters, and that's typically non reversible, though it would be nice to allow the former as well. snapshots are immutable, otherwise you get into the business of managing diverging branches, which I'd recommend against. Rolling back with the option to roll forward implies your entire FS is read-only, limiting its usefulness, even for testing. The job tracker, for example, won't start on a read-only dfs, let alone execute jobs. I'd recommend staying the course with non reversible rollbacks, while keeping in mind the desire for full snapshot functionality in future, which will allow read-only viewing of individual files or directories. > DFS Upgrade Proposal > -------------------- > > Key: HADOOP-702 > URL: http://issues.apache.org/jira/browse/HADOOP-702 > Project: Hadoop > Issue Type: New Feature > Components: dfs > Reporter: Konstantin Shvachko > Attachments: DFSUpgradeProposal.html > > > Currently the DFS cluster upgrade procedure is manual. > http://wiki.apache.org/lucene-hadoop/Hadoop_Upgrade > It is rather complicated and does not guarantee data recoverability in case > of software errors or administrator mistakes. > This is a description of utilities that make the upgrade process almost > automatic and minimize chance of loosing or corrupting data. > Please see the attached html file for details. -- This message is automatically generated by JIRA. - If you think it was sent incorrectly contact one of the administrators: http://issues.apache.org/jira/secure/Administrators.jspa - For more information on JIRA, see: http://www.atlassian.com/software/jira
