[ http://issues.apache.org/jira/browse/HADOOP-56?page=comments#action_12368159 ]
Konstantin Shvachko commented on HADOOP-56: ------------------------------------------- Sorry Bryan, I misinterpreted GUID as a group/user id. So, yes a global unique id is for identifying particular data instances of the file system. It can be generated by "format". And there shouldn't be any substantial overhead to support this. What I am trying to propose is to use the version number of the file system (as a software application), hard coded (rather than configured) and accessible via the getVersion() method, as a part of GUID. The version alone would have been sufficient to avoid the original problem with data loss, but GUID provides even better consistency. An additional advantage of versioning is that when the internal data layout for the name or data nodes is changed, one can provide conversion methods from one version to another. > hadoop nameserver does not recognise ndfs nameserver image > ---------------------------------------------------------- > > Key: HADOOP-56 > URL: http://issues.apache.org/jira/browse/HADOOP-56 > Project: Hadoop > Type: Bug > Components: dfs > Versions: 0.1 > Reporter: Yoram Arnon > Priority: Critical > Attachments: ndfs.tar.gz > > hadoop nameserver does not recognise ndfs image > Thus, upgrading from ndfs to hadoop dfs results in total data loss. > The upgrade should be seemless, with the new server recognising all previous > version that are not end-of-life'd. -- 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
